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Search found 75 results on 3 pages for 'frustum'.

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• Converting world space coordinate to screen space coordinate and getting incorrect range of values

  - by user1423893

  I'm attempting to convert from world space coordinates to screen space coordinates. I have the following code to transform my object position Vector3 screenSpacePoint = Vector3.Transform(object.WorldPosition, camera.ViewProjectionMatrix); The value does not appear to be in screen space coordinates and is not limited to a [-1, 1] range. What step have I missed out in the conversion process? EDIT: Projection Matrix Perspective(game.GraphicsDevice.Viewport.AspectRatio, nearClipPlaneZ, farClipPlaneZ); private void Perspective(float aspect_Ratio, float z_NearClipPlane, float z_FarClipPlane) { nearClipPlaneZ = z_NearClipPlane; farClipPlaneZ = z_FarClipPlane; float yZoom = 1f / (float)Math.Tan(fov * 0.5f); float xZoom = yZoom / aspect_Ratio; matrix_Projection.M11 = xZoom; matrix_Projection.M12 = 0f; matrix_Projection.M13 = 0f; matrix_Projection.M14 = 0f; matrix_Projection.M21 = 0f; matrix_Projection.M22 = yZoom; matrix_Projection.M23 = 0f; matrix_Projection.M24 = 0f; matrix_Projection.M31 = 0f; matrix_Projection.M32 = 0f; matrix_Projection.M33 = z_FarClipPlane / (nearClipPlaneZ - farClipPlaneZ); matrix_Projection.M34 = -1f; matrix_Projection.M41 = 0f; matrix_Projection.M42 = 0f; matrix_Projection.M43 = (nearClipPlaneZ * farClipPlaneZ) / (nearClipPlaneZ - farClipPlaneZ); matrix_Projection.M44 = 0f; } View Matrix // Make our view matrix Matrix.CreateFromQuaternion(ref orientation, out matrix_View); matrix_View.M41 = -Vector3.Dot(Right, position); matrix_View.M42 = -Vector3.Dot(Up, position); matrix_View.M43 = Vector3.Dot(Forward, position); matrix_View.M44 = 1f; // Create the combined view-projection matrix Matrix.Multiply(ref matrix_View, ref matrix_Projection, out matrix_ViewProj); // Update the bounding frustum boundingFrustum.SetMatrix(matrix_ViewProj);

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• State of the art Culling and Batching techniques in rendering

  - by Kristian Skarseth

  I'm currently working with upgrading and restructuring an OpenGL render engine. The engine is used for visualising large scenes of architectural data (buildings with interior), and the amount of objects can become rather large. As is the case with any building, there is a lot of occluded objects within walls, and you naturally only see the objects that are in the same room as you, or the exterior if you are on the outside. This leaves a large number of objects that should be occluded through occlusion culling and frustum culling. At the same time there is a lot of repetative geometry that can be batched in renderbatches, and also a lot of objects that can be rendered with instanced rendering. The way I see it, it can be difficult to combine renderbatching and culling in an optimal fashion. If you batch too many objects in the same VBO it's difficult to cull the objects on the CPU in order to skip rendering that batch. At the same time if you skip the culling on the cpu, a lot of objects will be processed by the GPU while they are not visible. If you skip batching copletely in order to more easily cull on the CPU, there will be an unwanted high amount of render calls. I have done some research into existing techniques and theories as to how these problems are solved in modern graphics, but I have not been able to find any concrete solution. An idea a colleague and me came up with was restricting batches to objects relatively close to eachother e.g all chairs in a room or within a radius of n meeters. This could be simplified and optimized through use of oct-trees. Does anyone have any pointers to techniques used for scene managment, culling, batching etc in state of the art modern graphics engines?

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• Center directional light shadow to the cameras eye

  - by Caesar

  I'm currently drawing my directional light shadow using this view and projection: XMFLOAT3 dir((float)pitch, (float)yaw, (float)roll); XMFLOAT3 center(0.0f, 0.0f, 0.0f); XMVECTOR lightDir = XMLoadFloat3(&dir); XMVECTOR lightPos = radius * lightDir; XMVECTOR targetPos = XMLoadFloat3(&center); XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f); XMMATRIX V = XMMatrixLookAtLH(lightPos, targetPos, up); // This is the view // Transform bounding sphere to light space. XMFLOAT3 sphereCenterLS; XMStoreFloat3(&sphereCenterLS, XMVector3TransformCoord(targetPos, V)); // Ortho frustum in light space encloses scene. float l = sphereCenterLS.x - radius; float b = sphereCenterLS.y - radius; float n = sphereCenterLS.z - radius; float r = sphereCenterLS.x + radius; float t = sphereCenterLS.y + radius; float f = sphereCenterLS.z + radius; XMMATRIX P = XMMatrixOrthographicOffCenterLH(l, r, b, t, n, f); // This is the projection Which works prefect if the center of my scene is at 0.0, 0.0, 0.0. What I would like to do is move the center of the scene relative to the cameras position. How can I do that?

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• Ray Tracing concers: Efficient Data Structure and Photon Mapping

  - by Grieverheart

  I'm trying to build a simple ray tracer for specific target scenes. An example of such scene can be seen below. I'm concerned as to what accelerating data structure would be most efficient in this case since all objects are touching but on the other hand, the scene is uniform. The objects in my ray tracer are stored as a collection of triangles, thus I also have access to individual triangles. Also, when trying to find the bounding box of the scene, how should infinite planes be handled? Should one instead use the viewing frustum to calculate the bounding box? A few other questions I have are about photon mapping. I've read the original paper by Jensen and many more material. In the compact data structure for the photon they introduce, they store photon power as 4 chars, which from my understanding is 3 chars for color and 1 for flux. But I don't understand how 1 char is enough to store a flux of the order of 1/n, where n is the number of photons (I'm also a bit confused about flux vs power). The other question about photon mapping is, if it would be more efficient in my case to store photons per object (or even per Object's triangle) instead of using a balanced kd-tree. Also, same question about bounding box of the scene but for photon mapping. How should one find a bounding box from the pov of the light when infinite planes are involved?

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• Scene graphs and spatial partitioning structures: What do you really need?

  - by tapirath

  I've been fiddling with 2D games for awhile and I'm trying to go into 3D game development. I thought I should get my basics right first. From what I read scene graphs hold your game objects/entities and their relation to each other like 'a tire' would be the child of 'a vehicle'. It's mainly used for frustum/occlusion culling and minimizing the collision checks between the objects. Spatial partitioning structures on the other hand are used to divide a big game object (like the map) to smaller parts so that you can gain performance by only drawing the relevant polygons and again minimizing the collision checks to those polygons only. Also a spatial partitioning data structure can be used as a node in a scene graph. But... I've been reading about both subjects and I've seen a lot of "scene graphs are useless" and "BSP performance gain is irrelevant with modern hardware" kind of articles. Also some of the game engines I've checked like gameplay3d and jmonkeyengine are only using a scene graph (That also may be because they don't want to limit the developers). Whereas games like Quake and Half-Life only use spatial partitioning. I'm aware that the usage of these structures very much depend on the type of the game you're developing so for the sake of clarity let's assume the game is a FPS like Counter-Strike with some better outdoor environment capabilities (like a terrain). The obvious question is which one is needed and why (considering the modern hardware capabilities). Thank you.

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• Looking for a small, light scene graph style abstraction lib for shader based OpenGL

  - by Pris

  I'm looking for a 'lean and mean' c/c++ scene graph library for OpenGL that doesn't use any deprecated functionality. It should be cross platform (strictly speaking I just dev on Linux so no love lost if it doesn't work on Windows), and it should be possible to deploy to mobile targets (ie OpenGLES2, and no crazy mandatory dependencies that wouldn't port well to modern mobile frameworks like iOS, Android, etc), with a license that's compatible with closed source software (LGPL or more liberal). Specific nice-to-haves would be: Cameras and Viewers (trackball, fly-by, etc) Object transform hierarchies (if B is a child of A, and you move A, B has the same transform applied to it) Simple animation Scene optimization (frustum culling, use VBOs, minimize state changes, etc) Text I've played around with OpenSceneGraph a lot and it's pretty amazing for fixed function pipeline stuff, but I've had a few of problems using it with the programmable pipeline and after going through their mailing list, it seems several people have had similar issues (going back years). Kitware's VES looks neat (http://www.vtk.org/Wiki/VES), but VES + VTK is pretty heavy. VTK is also typically for analyzing scientific data and I've read that it's not that appropriate for a general use case (not that great at rendering a lot of objects on scene,etc) I'm currently looking at VisualizationLibrary (http://www.visualizationlibrary.org/documentation/pag_gallery.html) which looks like it offers some of the functionality I'd like, but it doesn't explicitly support mobile targets. Other solutions like Ogre, Horde3D, Irrlicht, etc tend to be full on game engines and that's not really what I'm looking for. I'd like some suggestions for other libraries that I may have missed... please note I'm not willing to roll my own solution from scratch.

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• Central renderer for a given scene

  - by Loggie

  When creating a central rendering system for all game objects in a given scene I am trying to work out the best way to go about passing the scene to the render system to be rendered. If I have a scene managed by an arbitrary structure, i.e., an octree, bsp trees, quad-tree, kd tree, etc. What is the best way to pass this to the render system? The obvious problem is that if simply given the root node of the structure, the render system would require an intrinsic knowledge of the structure in order to traverse the structure. My solution to this is to clip all objects outside the frustum in the scene manager and then create a list of the objects which are left and pass this simple list to the render system, be it an array, a vector, a linked list, etc. (This would be a structure required by the render system as a means to know which objects should be rendered). The list would of course attempt to minimise OpenGL state changes by grouping objects that require the same rendering operations to be performed on them. I have been thinking a lot about this and started searching various terms on here and followed any additional information/links but I have not really found a definitive answer. The case may be that there is no definitive answer but I would appreciate some advice and tips. My question is, is this a reasonable solution to the problem? Are there any improvements that I could make? Are there any caveats I should know about? Side question: Am I right in assuming that octrees, bsp trees, etc are all forms of BVH?

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• How do I improve terrain rendering batch counts using DirectX?

  - by gamer747

  We have determined that our terrain rendering system needs some work to minimize the number of batches being transferred to the GPU in order to improve performance. I'm looking for suggestions on how best to improve what we're trying to accomplish. We logically split our terrain mesh into smaller grid cells which are 32x32 world units. Each cell has meta data that dictates the four 256x256 textures that are used for spatting along with the alpha blend data, shadow, and light mappings. Each cell contains 81 vertices in a 9x9 grid. Presently, we examine each cell and determine the four textures that are being used to spat the cell. We combine that geometry with any other cell that perhaps uses the same four textures regardless of spat order. If the spat order for a cell differs, the blend map is adjusted so that the spat order is maintained the same as other like cells and blending happens in the right order too. But even with this batching approach, it isn't uncommon when looking out across an area of open terrain to have between 1200-1700 batch count depending upon how frequently textures differ or have different texture blends are between cells. We are only doing frustum culling presently. So using texture spatting, are there other alternatives that can reduce the batch count and allow rendering to be extremely performance-friendly even under DirectX9c? We considered using texture atlases since we're targeting DirectX 9c & older OpenGL platforms but trying to repeat textures using atlases and shaders result in seam artifacts which we haven't been able to eliminate with the exception of disabling mipmapping. Disabling mipmapping results in poor quality textures from a distance. How have others batched together terrain geometry such that one could spat terrain using various textures, minimizing batch count and texture state switches so that rendering performance isn't negatively impacted?

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• translation/rotation of a HUD against a camera using vectors in Euclidian 3D space

  - by Jakob

  i've got 2 points in 3D space: the camera position and the camera lookAt. the camera movement is restricted akin to typical first person shooter games. you can move the cam freely, tilt horizontally and up to 90 degrees vertically, but not roll. so now i want to draw a HUD to the screen, on which i can move the mouse freely, with the position of the cursor correctly translating into 3D space. the easy part was to draw something directly in front of the camera. V0 = camPos; V1 = lookAt; V2 = lookAt-camPos; normalize V2; mutiply V2 according to camera frustum V3 = V0+V2 draw something at V3 now the part i don't get: i could use V3 and add to that the rotations of the cam combined with the x/y of the mouse cursor, somehow, right? that's what i want.

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• How should I think about perspectives and rotation in OpenGL ES?

  - by Omega

  As I start to write rendering code, how do I want to consider my drawing operations? Will they always be relative to a fixed coordinate system on the screen, or does this change based on the camera perspective? The best example I can try to come up with is say I'm at (0,0,0) and I draw a line to (3,3,3). If I change the perspective +1 on the X axis and conduct the same operation, does it happen at (4,3,3), or am I just getting a new view of the line still being made at (3,3,3)? When doing rotation, am I moving the point from which a frustum emanates, or am I moving the rendering underneath?

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• OpenGL ES perspective projection

  - by TimeManx

  I'm having a hard time understanding how glFrustum & gluPerspective work. I understand the concept of perspective projection but the functions aren't behaving how I expect them to. For example, if I set the frustum this way glFrustumf(0, 10, 0, 10, 1, 100) and have a rectangle at points 0, 0, 1, 0, 10, 1, 10, 10, 1, 10, 0, 1 then the rectangle is drawn with its left edge at -5 & right edge at 5, so the left half of the rectangle isn't visible. And if x is translated, I'd expect y to be too. But that doesn't happen either. In whatever examples I've seen, the coordinates for the projection matrix are taken as glFrustumf(-10, 10, -10, 10, 1, 100) but either way, whatever part is shown should be dependent on the rectangle's coordinates, right?

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• Voxel Face Crawling (Mesh simplification, possibly using greedy)

  - by Tim Winter

  This is in regards to a Minecraft-like terrain engine. I store blocks in chunks (16x256x16 blocks in a chunk). When I generate a chunk, I use multiple procedural techniques to set the terrain and to place objects. While generating, I keep one 1D array for the full chunk (solid or not) and a separate 1D array of solid blocks. After generation, I iterate through the solid blocks checking their neighbors so I only generate block faces that don't have solid neighbors. I store which faces to generate in their own list (that's 6 lists, one per possible face). When rendering a chunk, I render all lists in the camera's current chunk and only the lists facing the camera in all other chunks. Using a 2D atlas with this little shader trick Andrew Russell suggested, I want to merge similar faces together completely. That is, if they are in the same list (same normal), are adjacent to each other, have the same light level, etc. My assumption would be to have each of the 6 lists sorted by the axis they rest on, then by the other two axes (the list for the top of a block would be sorted by it's Y value, then X, then Z). With this alone, I could quite easily merge strips of faces, but I'm looking to merge more than just strips together when possible. I've read up on this greedy meshing algorithm, but I am having a lot of trouble understanding it. To even use it, I would think I'd need to perform a type of flood-fill per sorted list to get the groups of merge-able faces. Then, per group, perform the greedy algorithm. It all sounds awfully expensive if I would ever want dynamic terrain/lighting after initial generation. So, my question: To perform merging of faces as described (ignoring whether it's a bad idea for dynamic terrain/lighting), is there perhaps an algorithm that is simpler to implement? I would also quite happily accept an answer that walks me through the greedy algorithm in a much simpler way (a link or explanation). I don't mind a slight performance decrease if it's easier to implement or even if it's only a little better than just doing strips. I worry that most algorithms focus on triangles rather than quads and using a 2D atlas the way I am, I don't know that I could implement something triangle based with my current skills. PS: I already frustum cull per chunk and as described, I also cull faces between solid blocks. I don't occlusion cull yet and may never.

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• 2D Rendering with OpenGL ES 2.0 on Android (matrices not working)

  - by TranquilMarmot

  So I'm trying to render two moving quads, each at different locations. My shaders are as simple as possible (vertices are only transformed by the modelview-projection matrix, there's only one color). Whenever I try and render something, I only end up with slivers of color! I've only done work with 3D rendering in OpenGL before so I'm having issues with 2D stuff. Here's my basic rendering loop, simplified a bit (I'm using the Matrix manipulation methods provided by android.opengl.Matrix and program is a custom class I created that just calls GLES20.glUniformMatrix4fv()): Matrix.orthoM(projection, 0, 0, windowWidth, 0, windowHeight, -1, 1); program.setUniformMatrix4f("Projection", projection); At this point, I render the quads (this is repeated for each quad): Matrix.setIdentityM(modelview, 0); Matrix.translateM(modelview, 0, quadX, quadY, 0); program.setUniformMatrix4f("ModelView", modelview); quad.render(); // calls glDrawArrays and all I see is a sliver of the color each quad is! I'm at my wits end here, I've tried everything I can think of and I'm at the point where I'm screaming at my computer and tossing phones across the room. Anybody got any pointers? Am I using ortho wrong? I'm 100% sure I'm rendering everything at a Z value of 0. I tried using frustumM instead of orthoM, which made it so that I could see the quads but they would get totally skewed whenever they got moved, which makes sense if I correctly understand the way frustum works (it's more for 3D rendering, anyway). If it makes any difference, I defined my viewport with GLES20.glViewport(0, 0, windowWidth, windowHeight); Where windowWidth and windowHeight are the same values that are pased to orthoM It might be worth noting that the android.opengl.Matrix methods take in an offset as the second parameter so that multiple matrices can be shoved into one array, so that'w what the first 0 is for For reference, here's my vertex shader code: uniform mat4 ModelView; uniform mat4 Projection; attribute vec4 vPosition; void main() { mat4 mvp = Projection * ModelView; gl_Position = vPosition * mvp; } I tried swapping Projection * ModelView with ModelView * Projection but now I just get some really funky looking shapes... EDIT Okay, I finally figured it out! (Note: Since I'm new here (longtime lurker!) I can't answer my own question for a few hours, so as soon as I can I'll move this into an actual answer to the question) I changed Matrix.orthoM(projection, 0, 0, windowWidth, 0, windowHeight, -1, 1); to float ratio = windowWwidth / windowHeight; Matrix.orthoM(projection, 0, 0, ratio, 0, 1, -1, 1); I then had to scale my projection matrix to make it a lot smaller with Matrix.scaleM(projection, 0, 0.05f, 0.05f, 1.0f);. I then added an offset to the modelview translations to simulate a camera so that I could center on my action (so Matrix.translateM(modelview, 0, quadX, quadY, 0); was changed to Matrix.translateM(modelview, 0, quadX + camX, quadY + camY, 0);) Thanks for the help, all!

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• C++ problem with assimp 3D model loader

  - by Brendan Webster

  In my game I have model loading functions for Assimp model loading library. I can load the model and render it, but the model displays incorrectly. The models load in as if they were using a seperate projection matrix. I have looked over my code over and over again, but I probably keep on missing the obvious reason why this is happening. Here is an image of my game: It's simply a 6 sided cube, but it's off big time! Here are my code snippets for rendering the cube to the screen: void C_MediaLoader::display(void) { float tmp; glTranslatef(0,0,0); // rotate it around the y axis glRotatef(angle,0.f,0.f,1.f); glColor4f(1,1,1,1); // scale the whole asset to fit into our view frustum tmp = scene_max.x-scene_min.x; tmp = aisgl_max(scene_max.y - scene_min.y,tmp); tmp = aisgl_max(scene_max.z - scene_min.z,tmp); tmp = (1.f / tmp); glScalef(tmp/5, tmp/5, tmp/5); // center the model //glTranslatef( -scene_center.x, -scene_center.y, -scene_center.z ); // if the display list has not been made yet, create a new one and // fill it with scene contents if(scene_list == 0) { scene_list = glGenLists(1); glNewList(scene_list, GL_COMPILE); // now begin at the root node of the imported data and traverse // the scenegraph by multiplying subsequent local transforms // together on GL's matrix stack. recursive_render(scene, scene->mRootNode); glEndList(); } glCallList(scene_list); } void C_MediaLoader::recursive_render (const struct aiScene *sc, const struct aiNode* nd) { unsigned int i; unsigned int n = 0, t; struct aiMatrix4x4 m = nd->mTransformation; // update transform aiTransposeMatrix4(&m); glPushMatrix(); glMultMatrixf((float*)&m); // draw all meshes assigned to this node for (; n < nd->mNumMeshes; ++n) { const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]]; apply_material(sc->mMaterials[mesh->mMaterialIndex]); if(mesh->mNormals == NULL) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } for (t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; GLenum face_mode; switch(face->mNumIndices) { case 1: face_mode = GL_POINTS; break; case 2: face_mode = GL_LINES; break; case 3: face_mode = GL_TRIANGLES; break; default: face_mode = GL_POLYGON; break; } glBegin(face_mode); for(i = 0; i < face->mNumIndices; i++) { int index = face->mIndices[i]; if(mesh->mColors[0] != NULL) glColor4fv((GLfloat*)&mesh->mColors[0][index]); if(mesh->mNormals != NULL) glNormal3fv(&mesh->mNormals[index].x); glVertex3fv(&mesh->mVertices[index].x); } glEnd(); } } // draw all children for (n = 0; n < nd->mNumChildren; ++n) { recursive_render(sc, nd->mChildren[n]); } glPopMatrix(); } Sorry there is so much code to look through, but I really cannot find the problem, and I would love to have help.

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• Help me get my 3D camera to look like the ones in RTS

  - by rFactor

  I am a newbie in 3D game development and I am trying to make a real-time strategy game. I am struggling with the camera currently as I am unable to make it look like they do in RTS games. Here is my Camera.cs class using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Input; namespace BB { public class Camera : Microsoft.Xna.Framework.GameComponent { public Matrix view; public Matrix projection; protected Game game; KeyboardState currentKeyboardState; Vector3 cameraPosition = new Vector3(600.0f, 0.0f, 600.0f); Vector3 cameraForward = new Vector3(0, -0.4472136f, -0.8944272f); BoundingFrustum cameraFrustum = new BoundingFrustum(Matrix.Identity); // Light direction Vector3 lightDir = new Vector3(-0.3333333f, 0.6666667f, 0.6666667f); public Camera(Game game) : base(game) { this.game = game; } public override void Initialize() { this.view = Matrix.CreateLookAt(this.cameraPosition, this.cameraPosition + this.cameraForward, Vector3.Up); this.projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, this.game.renderer.aspectRatio, 1, 10000); base.Initialize(); } /* Handles the user input * @ param GameTime gameTime */ private void HandleInput(GameTime gameTime) { float time = (float)gameTime.ElapsedGameTime.TotalMilliseconds; currentKeyboardState = Keyboard.GetState(); } void UpdateCamera(GameTime gameTime) { float time = (float)gameTime.ElapsedGameTime.TotalMilliseconds; // Check for input to rotate the camera. float pitch = 0.0f; float turn = 0.0f; if (currentKeyboardState.IsKeyDown(Keys.Up)) pitch += time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Down)) pitch -= time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Left)) turn += time * 0.001f; if (currentKeyboardState.IsKeyDown(Keys.Right)) turn -= time * 0.001f; Vector3 cameraRight = Vector3.Cross(Vector3.Up, cameraForward); Vector3 flatFront = Vector3.Cross(cameraRight, Vector3.Up); Matrix pitchMatrix = Matrix.CreateFromAxisAngle(cameraRight, pitch); Matrix turnMatrix = Matrix.CreateFromAxisAngle(Vector3.Up, turn); Vector3 tiltedFront = Vector3.TransformNormal(cameraForward, pitchMatrix * turnMatrix); // Check angle so we cant flip over if (Vector3.Dot(tiltedFront, flatFront) > 0.001f) { cameraForward = Vector3.Normalize(tiltedFront); } // Check for input to move the camera around. if (currentKeyboardState.IsKeyDown(Keys.W)) cameraPosition += cameraForward * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.S)) cameraPosition -= cameraForward * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.A)) cameraPosition += cameraRight * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.D)) cameraPosition -= cameraRight * time * 0.4f; if (currentKeyboardState.IsKeyDown(Keys.R)) { cameraPosition = new Vector3(0, 50, 50); cameraForward = new Vector3(0, 0, -1); } cameraForward.Normalize(); // Create the new view matrix view = Matrix.CreateLookAt(cameraPosition, cameraPosition + cameraForward, Vector3.Up); // Set the new frustum value cameraFrustum.Matrix = view * projection; } public override void Update(Microsoft.Xna.Framework.GameTime gameTime) { HandleInput(gameTime); UpdateCamera(gameTime); } } } The problem is that the initial view is looking in a horizontal direction. I would like to have an RTS like top down view (but with a slight pitch). Can you help me out?

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• What is the best Broadphase Interface for moving spheres?

  - by Molmasepic

  As of now I am working on optimizing the performance of the physics and collision, and as of now I am having some slowdowns on my other computers from my main. I have well over 3000 btSphereShape Rigidbodies and 2/3 of them do not move at all, but I am noticing(by the profile below) that collision is taking a bit of time to maneuver. Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls ms/call ms/call name 10.09 0.65 0.65 SphereTriangleDetector::collide(btVector3 const&, btVector3&, btVector3&, float&, float&, float) 7.61 1.14 0.49 btSphereTriangleCollisionAlgorithm::processCollision(btCollisionObject*, btCollisionObject*, btDispatcherInfo const&, btManifoldResult*) 5.59 1.50 0.36 btConvexTriangleCallback::processTriangle(btVector3*, int, int) 5.43 1.85 0.35 btQuantizedBvh::reportAabbOverlappingNodex(btNodeOverlapCallback*, btVector3 const&, btVector3 const&) const 4.97 2.17 0.32 btBvhTriangleMeshShape::processAllTriangles(btTriangleCallback*, btVector3 const&, btVector3 const&) const::MyNodeOverlapCallback::processNode(int, int) 4.19 2.44 0.27 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGeneric(btRigidBody&, btRigidBody&, btSolverConstraint const&) 4.04 2.70 0.26 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimit(btRigidBody&, btRigidBody&, btSolverConstraint const&) 3.73 2.94 0.24 Ogre::OctreeSceneManager::walkOctree(Ogre::OctreeCamera*, Ogre::RenderQueue*, Ogre::Octree*, Ogre::VisibleObjectsBoundsInfo*, bool, bool) 3.42 3.16 0.22 btTriangleShape::getVertex(int, btVector3&) const 2.48 3.32 0.16 Ogre::Frustum::isVisible(Ogre::AxisAlignedBox const&, Ogre::FrustumPlane*) const 2.33 3.47 0.15 1246357 0.00 0.00 Gorilla::Layer::setVisible(bool) 2.33 3.62 0.15 SphereTriangleDetector::getClosestPoints(btDiscreteCollisionDetectorInterface::ClosestPointInput const&, btDiscreteCollisionDetectorInterface::Result&, btIDebugDraw*, bool) 1.86 3.74 0.12 btCollisionDispatcher::findAlgorithm(btCollisionObject*, btCollisionObject*, btPersistentManifold*) 1.86 3.86 0.12 btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstraint&, btCollisionObject*, btCollisionObject*, btManifoldPoint&, btContactSolverInfo const&, btVector3&, float&, float&, btVector3&, btVector3&) 1.71 3.97 0.11 btTriangleShape::getEdge(int, btVector3&, btVector3&) const 1.55 4.07 0.10 _Unwind_SjLj_Register 1.55 4.17 0.10 _Unwind_SjLj_Unregister 1.55 4.27 0.10 Ogre::D3D9HardwareVertexBuffer::updateBufferResources(char const*, Ogre::D3D9HardwareVertexBuffer::BufferResources*) 1.40 4.36 0.09 btManifoldResult::addContactPoint(btVector3 const&, btVector3 const&, float) 1.40 4.45 0.09 btSequentialImpulseConstraintSolver::setupFrictionConstraint(btSolverConstraint&, btVector3 const&, btRigidBody*, btRigidBody*, btManifoldPoint&, btVector3 const&, btVector3 const&, btCollisionObject*, btCollisionObject*, float, float, float) 1.24 4.53 0.08 btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold*, btContactSolverInfo const&) 1.09 4.60 0.07 408760 0.00 0.00 Living::MapHide() 1.09 4.67 0.07 btSphereTriangleCollisionAlgorithm::~btSphereTriangleCollisionAlgorithm() 1.09 4.74 0.07 inflate_fast EDIT: Updated to show current Profile. I have only listed the functions using over 1% time from the many functions that are being used. Another thing is that each monster has a certain area that they stay in and are only active when a player is in said area. I was wondering if maybe there is a way to deactivate the non-active monsters from bullet(reactivating once in the area again) or maybe theres a different broadphase interface that I should use. The current BPI is btDbvtBroadphase. EDIT: Here is the Profile on the other computer(the top one is my main) Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls ms/call ms/call name 12.18 1.19 1.19 SphereTriangleDetector::collide(btVector3 const&, btVector3&, btVector3&, float&, float&, float) 6.76 1.85 0.66 btSphereTriangleCollisionAlgorithm::processCollision(btCollisionObject*, btCollisionObject*, btDispatcherInfo const&, btManifoldResult*) 5.83 2.42 0.57 btQuantizedBvh::reportAabbOverlappingNodex(btNodeOverlapCallback*, btVector3 const&, btVector3 const&) const 5.12 2.92 0.50 btConvexTriangleCallback::processTriangle(btVector3*, int, int) 4.61 3.37 0.45 btTriangleShape::getVertex(int, btVector3&) const 4.09 3.77 0.40 _Unwind_SjLj_Register 3.48 4.11 0.34 btBvhTriangleMeshShape::processAllTriangles(btTriangleCallback*, btVector3 const&, btVector3 const&) const::MyNodeOverlapCallback::processNode(int, int) 2.46 4.35 0.24 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimit(btRigidBody&, btRigidBody&, btSolverConstraint const&) 2.15 4.56 0.21 _Unwind_SjLj_Unregister 2.15 4.77 0.21 SphereTriangleDetector::getClosestPoints(btDiscreteCollisionDetectorInterface::ClosestPointInput const&, btDiscreteCollisionDetectorInterface::Result&, btIDebugDraw*, bool) 1.84 4.95 0.18 btTriangleShape::getEdge(int, btVector3&, btVector3&) const 1.64 5.11 0.16 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGeneric(btRigidBody&, btRigidBody&, btSolverConstraint const&) 1.54 5.26 0.15 btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstraint&, btCollisionObject*, btCollisionObject*, btManifoldPoint&, btContactSolverInfo const&, btVector3&, float&, float&, btVector3&, btVector3&) 1.43 5.40 0.14 Ogre::D3D9HardwareVertexBuffer::updateBufferResources(char const*, Ogre::D3D9HardwareVertexBuffer::BufferResources*) 1.33 5.53 0.13 btManifoldResult::addContactPoint(btVector3 const&, btVector3 const&, float) 1.13 5.64 0.11 btRigidBody::predictIntegratedTransform(float, btTransform&) 1.13 5.75 0.11 btTriangleIndexVertexArray::getLockedReadOnlyVertexIndexBase(unsigned char const**, int&, PHY_ScalarType&, int&, unsigned char const**, int&, int&, PHY_ScalarType&, int) const 1.02 5.85 0.10 btSphereTriangleCollisionAlgorithm::CreateFunc::CreateCollisionAlgorithm(btCollisionAlgorithmConstructionInfo&, btCollisionObject*, btCollisionObject*) 1.02 5.95 0.10 btSphereTriangleCollisionAlgorithm::btSphereTriangleCollisionAlgorithm(btPersistentManifold*, btCollisionAlgorithmConstructionInfo const&, btCollisionObject*, btCollisionObject*, bool) Edited same as other Profile.

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• Shadows shimmer when camera moves

  - by Chad Layton

  I've implemented shadow maps in my simple block engine as an exercise. I'm using one directional light and using the view volume to create the shadow matrices. I'm experiencing some problems with the shadows shimmering when the camera moves and I'd like to know if it's an issue with my implementation or just an issue with basic/naive shadow mapping itself. Here's a video: http://www.youtube.com/watch?v=vyprATt5BBg&feature=youtu.be Here's the code I use to create the shadow matrices. The commented out code is my original attempt to perfectly fit the view frustum. You can also see my attempt to try clamping movement to texels in the shadow map which didn't seem to make any difference. Then I tried using a bounding sphere instead, also to no apparent effect. public void CreateViewProjectionTransformsToFit(Camera camera, out Matrix viewTransform, out Matrix projectionTransform, out Vector3 position) { BoundingSphere cameraViewFrustumBoundingSphere = BoundingSphere.CreateFromFrustum(camera.ViewFrustum); float lightNearPlaneDistance = 1.0f; Vector3 lookAt = cameraViewFrustumBoundingSphere.Center; float distanceFromLookAt = cameraViewFrustumBoundingSphere.Radius + lightNearPlaneDistance; Vector3 directionFromLookAt = -Direction * distanceFromLookAt; position = lookAt + directionFromLookAt; viewTransform = Matrix.CreateLookAt(position, lookAt, Vector3.Up); float lightFarPlaneDistance = distanceFromLookAt + cameraViewFrustumBoundingSphere.Radius; float diameter = cameraViewFrustumBoundingSphere.Radius * 2.0f; Matrix.CreateOrthographic(diameter, diameter, lightNearPlaneDistance, lightFarPlaneDistance, out projectionTransform); //Vector3 cameraViewFrustumCentroid = camera.ViewFrustum.GetCentroid(); //position = cameraViewFrustumCentroid - (Direction * (camera.FarPlaneDistance - camera.NearPlaneDistance)); //viewTransform = Matrix.CreateLookAt(position, cameraViewFrustumCentroid, Up); //Vector3[] cameraViewFrustumCornersWS = camera.ViewFrustum.GetCorners(); //Vector3[] cameraViewFrustumCornersLS = new Vector3[8]; //Vector3.Transform(cameraViewFrustumCornersWS, ref viewTransform, cameraViewFrustumCornersLS); //Vector3 min = cameraViewFrustumCornersLS[0]; //Vector3 max = cameraViewFrustumCornersLS[0]; //for (int i = 1; i < 8; i++) //{ // min = Vector3.Min(min, cameraViewFrustumCornersLS[i]); // max = Vector3.Max(max, cameraViewFrustumCornersLS[i]); //} //// Clamp to nearest texel //float texelSize = 1.0f / Renderer.ShadowMapSize; //min.X -= min.X % texelSize; //min.Y -= min.Y % texelSize; //min.Z -= min.Z % texelSize; //max.X -= max.X % texelSize; //max.Y -= max.Y % texelSize; //max.Z -= max.Z % texelSize; //// We just use an orthographic projection matrix. The sun is so far away that it's rays are essentially parallel. //Matrix.CreateOrthographicOffCenter(min.X, max.X, min.Y, max.Y, -max.Z, -min.Z, out projectionTransform); } And here's the relevant part of the shader: if (CastShadows) { float4 positionLightCS = mul(float4(position, 1.0f), LightViewProj); float2 texCoord = clipSpaceToScreen(positionLightCS) + 0.5f / ShadowMapSize; float shadowMapDepth = tex2D(ShadowMapSampler, texCoord).r; float distanceToLight = length(LightPosition - position); float bias = 0.2f; if (shadowMapDepth < (distanceToLight - bias)) { return float4(0.0f, 0.0f, 0.0f, 0.0f); } } The shimmer is slightly better if I drastically reduce the view volume but I think that's mostly just because the texels become smaller and it's harder to notice them flickering back and forth. I'd appreciate any insight, I'd very much like to understand what's going on before I try other techniques.

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• Problem with Assimp 3D model loader

  - by Brendan Webster

  In my game I have model loading functions for Assimp model loading library. I can load the model and render it, but the model displays incorrectly. The models load in as if they were using a seperate projection matrix. I have looked over my code over and over again, but I probably keep on missing the obvious reason why this is happening. Here is an image of my game: It's simply a 6 sided cube, but it's off big time! Here are my code snippets for rendering the cube to the screen: void C_MediaLoader::display(void) { float tmp; glTranslatef(0,0,0); // rotate it around the y axis glRotatef(angle,0.f,0.f,1.f); glColor4f(1,1,1,1); // scale the whole asset to fit into our view frustum tmp = scene_max.x-scene_min.x; tmp = aisgl_max(scene_max.y - scene_min.y,tmp); tmp = aisgl_max(scene_max.z - scene_min.z,tmp); tmp = (1.f / tmp); glScalef(tmp/5, tmp/5, tmp/5); // center the model //glTranslatef( -scene_center.x, -scene_center.y, -scene_center.z ); // if the display list has not been made yet, create a new one and // fill it with scene contents if(scene_list == 0) { scene_list = glGenLists(1); glNewList(scene_list, GL_COMPILE); // now begin at the root node of the imported data and traverse // the scenegraph by multiplying subsequent local transforms // together on GL's matrix stack. recursive_render(scene, scene->mRootNode); glEndList(); } glCallList(scene_list); } void C_MediaLoader::recursive_render (const struct aiScene *sc, const struct aiNode* nd) { unsigned int i; unsigned int n = 0, t; struct aiMatrix4x4 m = nd->mTransformation; // update transform aiTransposeMatrix4(&m); glPushMatrix(); glMultMatrixf((float*)&m); // draw all meshes assigned to this node for (; n < nd->mNumMeshes; ++n) { const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]]; apply_material(sc->mMaterials[mesh->mMaterialIndex]); if(mesh->mNormals == NULL) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } for (t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; GLenum face_mode; switch(face->mNumIndices) { case 1: face_mode = GL_POINTS; break; case 2: face_mode = GL_LINES; break; case 3: face_mode = GL_TRIANGLES; break; default: face_mode = GL_POLYGON; break; } glBegin(face_mode); for(i = 0; i < face->mNumIndices; i++) { int index = face->mIndices[i]; if(mesh->mColors[0] != NULL) glColor4fv((GLfloat*)&mesh->mColors[0][index]); if(mesh->mNormals != NULL) glNormal3fv(&mesh->mNormals[index].x); glVertex3fv(&mesh->mVertices[index].x); } glEnd(); } } // draw all children for (n = 0; n < nd->mNumChildren; ++n) { recursive_render(sc, nd->mChildren[n]); } glPopMatrix(); } Sorry there is so much code to look through, but I really cannot find the problem, and I would love to have help.

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• How to translate along Z axis in OpenTK

  - by JeremyJAlpha

  I am playing around with an OpenGL sample application I downloaded for Xamarin-Android. The sample application produces a rotating colored cube I would simply like to edit it so that the rotating cube is translated along the Z axis and disappears into the distance. I modified the code by: adding an cumulative variable to store my Z distance, adding GL.Enable(All.DepthBufferBit) - unsure if I put it in the right place, adding GL.Translate(0.0f, 0.0f, Depth) - before the rotate functions, Result: cube rotates a couple of times then disappears, it seems to be getting clipped out of the frustum. So my question is what is the correct way to use and initialize the Z buffer and get the cube to travel along the Z axis? I am sure I am missing some function calls but am unsure of what they are and where to put them. I apologise in advance as this is very basic stuff but am still learning :P, I would appreciate it if anyone could show me the best way to get the cube to still rotate but to also move along the Z axis. I have commented all my modifications in the code: // This gets called when the drawing surface is ready protected override void OnLoad (EventArgs e) { // this call is optional, and meant to raise delegates // in case any are registered base.OnLoad (e); // UpdateFrame and RenderFrame are called // by the render loop. This is takes effect // when we use 'Run ()', like below UpdateFrame += delegate (object sender, FrameEventArgs args) { // Rotate at a constant speed for (int i = 0; i < 3; i ++) rot [i] += (float) (rateOfRotationPS [i] * args.Time); }; RenderFrame += delegate { RenderCube (); }; GL.Enable(All.DepthBufferBit); //Added by Noob GL.Enable(All.CullFace); GL.ShadeModel(All.Smooth); GL.Hint(All.PerspectiveCorrectionHint, All.Nicest); // Run the render loop Run (30); } void RenderCube () { GL.Viewport(0, 0, viewportWidth, viewportHeight); GL.MatrixMode (All.Projection); GL.LoadIdentity (); if ( viewportWidth > viewportHeight ) { GL.Ortho(-1.5f, 1.5f, 1.0f, -1.0f, -1.0f, 1.0f); } else { GL.Ortho(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f); } GL.MatrixMode (All.Modelview); GL.LoadIdentity (); Depth -= 0.02f; //Added by Noob GL.Translate(0.0f,0.0f,Depth); //Added by Noob GL.Rotate (rot[0], 1.0f, 0.0f, 0.0f); GL.Rotate (rot[1], 0.0f, 1.0f, 0.0f); GL.Rotate (rot[2], 0.0f, 1.0f, 0.0f); GL.ClearColor (0, 0, 0, 1.0f); GL.Clear (ClearBufferMask.ColorBufferBit); GL.VertexPointer(3, All.Float, 0, cube); GL.EnableClientState (All.VertexArray); GL.ColorPointer (4, All.Float, 0, cubeColors); GL.EnableClientState (All.ColorArray); GL.DrawElements(All.Triangles, 36, All.UnsignedByte, triangles); SwapBuffers (); }

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• Projective texture and deferred lighting

  - by Vodácek

  In my previous question, I asked whether it is possible to do projective texturing with deferred lighting. Now (more than half a year later) I have a problem with my implementation of the same thing. I am trying to apply this technique in light pass. (my projector doesn't affect albedo). I have this projector View a Projection matrix: Matrix projection = Matrix.CreateOrthographicOffCenter(-halfWidth * Scale, halfWidth * Scale, -halfHeight * Scale, halfHeight * Scale, 1, 100000); Matrix view = Matrix.CreateLookAt(Position, Target, Vector3.Up); Where halfWidth and halfHeight is are half of the texture's width and height, Position is the Projector's position and target is the projector's target. This seems to be ok. I am drawing full screen quad with this shader: float4x4 InvViewProjection; texture2D DepthTexture; texture2D NormalTexture; texture2D ProjectorTexture; float4x4 ProjectorViewProjection; sampler2D depthSampler = sampler_state { texture = <DepthTexture>; minfilter = point; magfilter = point; mipfilter = point; }; sampler2D normalSampler = sampler_state { texture = <NormalTexture>; minfilter = point; magfilter = point; mipfilter = point; }; sampler2D projectorSampler = sampler_state { texture = <ProjectorTexture>; AddressU = Clamp; AddressV = Clamp; }; float viewportWidth; float viewportHeight; // Calculate the 2D screen position of a 3D position float2 postProjToScreen(float4 position) { float2 screenPos = position.xy / position.w; return 0.5f * (float2(screenPos.x, -screenPos.y) + 1); } // Calculate the size of one half of a pixel, to convert // between texels and pixels float2 halfPixel() { return 0.5f / float2(viewportWidth, viewportHeight); } struct VertexShaderInput { float4 Position : POSITION0; }; struct VertexShaderOutput { float4 Position :POSITION0; float4 PositionCopy : TEXCOORD1; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { VertexShaderOutput output; output.Position = input.Position; output.PositionCopy=output.Position; return output; } float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { float2 texCoord =postProjToScreen(input.PositionCopy) + halfPixel(); // Extract the depth for this pixel from the depth map float4 depth = tex2D(depthSampler, texCoord); //return float4(depth.r,0,0,1); // Recreate the position with the UV coordinates and depth value float4 position; position.x = texCoord.x * 2 - 1; position.y = (1 - texCoord.y) * 2 - 1; position.z = depth.r; position.w = 1.0f; // Transform position from screen space to world space position = mul(position, InvViewProjection); position.xyz /= position.w; //compute projection float3 projection=tex2D(projectorSampler,postProjToScreen(mul(position,ProjectorViewProjection)) + halfPixel()); return float4(projection,1); } In first part of pixel shader is recovered position from G-buffer (this code I am using in other shaders without any problem) and then is tranformed to projector viewprojection space. Problem is that projection doesn't appear. Here is an image of my situation: The green lines are the rendered projector frustum. Where is my mistake hidden? I am using XNA 4. Thanks for advice and sorry for my English. EDIT: Shader above is working but projection was too small. When I changed the Scale property to a large value (e.g. 100), the projection appears. But when the camera moves toward the projection, the projection expands, as can bee seen on this YouTube video.

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• Opengl: fit a quad to screen, given the value of Z.

  - by hytparadisee

  Short Version of the question: I will put a quad. I know the width and height of the screen in window coordinates, i know the Z-coordinates of the quad in 3D. I know the FOVY, I know the aspect. The quad will be put along Z-axis, My camera doesn't move (placed at 0, 0, 0). I want to find out the width and height of the quad IN 3D COORDINATES that will fit exactly onto my screen. Long Version of the question: I would like to put a quad along the Z-axis at the specified offset Z, I would like to find out the width and height of the quad that will exactly fill the entire screen. I used to have a post on gamedev.net that uses a formula similar to the following: *dist = Z * tan ( FOV / 2 )* Now I can never find the post! Though it's similar, it is still different, because I remembered in that working formula, they do make use of screenWidth and screenHeight, which are the width and height of the screen in window coordinates. I am not really familiar with concepts like frustum, fov and aspect so that's why I can't work out the formula on my own. Besides, I am sure I don't need gluUnproject (I tried it, but the results are way off). It's not some gl calls, it's just a math formula that can find out the width and height in 3D space that can fill the entire screen, IF Z offset, width in window coordinates, and height in window coordinates, are known. Thanks all in advance.

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• Apply Quaternion to Camera in libGDX

  - by Alex_Hyzer_Kenoyer

  I am trying to rotate my camera using a Quaternion in libGDX. I have a Quaternion created and being manipulated but I have no idea how to apply it to the camera, everything I've tried hasn't moved the camera at all. Here is how I set up the rotation Quaternion: public void rotateX(float amount) { tempQuat.set(tempVector.set(1.0f, 0.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = rotation.mul(tempQuat); } public void rotateY(float amount) { tempQuat.set(tempVector.set(0.0f, 1.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = tempQuat.mul(rotation); } Here is how I am trying to update the camera (Same update method as the original libGDX version but I added the part about the rotation matrix to the top): public void update(boolean updateFrustum) { float[] matrix = new float[16]; rotation.toMatrix(matrix); Matrix4 m = new Matrix4(); m.set(matrix); camera.view.mul(m); //camera.direction.mul(m).nor(); //camera.up.mul(m).nor(); float aspect = camera.viewportWidth / camera.viewportHeight; camera.projection.setToProjection(Math.abs(camera.near), Math.abs(camera.far), camera.fieldOfView, aspect); camera.view.setToLookAt(camera.position, tempVector.set(camera.position).add(camera.direction), camera.up); camera.combined.set(camera.projection); Matrix4.mul(camera.combined.val, camera.view.val); if (updateFrustum) { camera.invProjectionView.set(camera.combined); Matrix4.inv(camera.invProjectionView.val); camera.frustum.update(camera.invProjectionView); } }

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• WebGL First Person Camera - Matrix issues

  - by Ryan Welsh

  I have been trying to make a WebGL FPS camera.I have all the inputs working correctly (I think) but when it comes to applying the position and rotation data to the view matrix I am a little lost. The results can be viewed here http://thistlestaffing.net/masters/camera/index.html and the code here var camera = { yaw: 0.0, pitch: 0.0, moveVelocity: 1.0, position: [0.0, 0.0, -70.0] }; var viewMatrix = mat4.create(); var rotSpeed = 0.1; camera.init = function(canvas){ var ratio = canvas.clientWidth / canvas.clientHeight; var left = -1; var right = 1; var bottom = -1.0; var top = 1.0; var near = 1.0; var far = 1000.0; mat4.frustum(projectionMatrix, left, right, bottom, top, near, far); viewMatrix = mat4.create(); mat4.rotateY(viewMatrix, viewMatrix, camera.yaw); mat4.rotateX(viewMatrix, viewMatrix, camera.pitch); mat4.translate(viewMatrix, viewMatrix, camera.position); } camera.update = function(){ viewMatrix = mat4.create(); mat4.rotateY(viewMatrix, viewMatrix, camera.yaw); mat4.rotateX(viewMatrix, viewMatrix, camera.pitch); mat4.translate(viewMatrix, viewMatrix, camera.position); } //prevent camera pitch from going above 90 and reset yaw when it goes over 360 camera.lockCamera = function(){ if(camera.pitch > 90.0){ camera.pitch = 90; } if(camera.pitch < -90){ camera.pitch = -90; } if(camera.yaw <0.0){ camera.yaw = camera.yaw + 360; } if(camera.yaw >360.0){ camera.yaw = camera.yaw - 0.0; } } camera.translateCamera = function(distance, direction){ //calculate where we are looking at in radians and add the direction we want to go in ie WASD keys var radian = glMatrix.toRadian(camera.yaw + direction); //console.log(camera.position[3], radian, distance, direction); //calc X coord camera.position[0] = camera.position[0] - Math.sin(radian) * distance; //calc Z coord camera.position[2] = camera.position [2] - Math.cos(radian) * distance; console.log(camera.position [2] - (Math.cos(radian) * distance)); } camera.rotateUp = function(distance, direction){ var radian = glMatrix.toRadian(camera.pitch + direction); //calc Y coord camera.position[1] = camera.position[1] + Math.sin(radian) * distance; } camera.moveForward = function(){ if(camera.pitch!=90 && camera.pitch!=-90){ camera.translateCamera(-camera.moveVelocity, 0.0); } camera.rotateUp(camera.moveVelocity, 0.0); } camera.moveBack = function(){ if(camera.pitch!=90 && camera.pitch!=-90){ camera.translateCamera(-camera.moveVelocity, 180.0); } camera.rotateUp(camera.moveVelocity, 180.0); } camera.moveLeft = function(){ camera.translateCamera(-camera.moveVelocity, 270.0); } camera.moveRight = function(){ camera.translateCamera(-camera.moveVelocity, 90.0); } camera.lookUp = function(){ camera.pitch = camera.pitch + rotSpeed; camera.lockCamera(); } camera.lookDown = function(){ camera.pitch = camera.pitch - rotSpeed; camera.lockCamera(); } camera.lookLeft = function(){ camera.yaw= camera.yaw - rotSpeed; camera.lockCamera(); } camera.lookRight = function(){ camera.yaw = camera.yaw + rotSpeed; camera.lockCamera(); } . If there is no problem with my camera then I am doing some matrix calculations within my draw function where a problem might be. //position cube 1 worldMatrix = mat4.create(); mvMatrix = mat4.create(); mat4.translate(worldMatrix, worldMatrix, [-20.0, 0.0, -30.0]); mat4.multiply(mvMatrix, worldMatrix, viewMatrix); setShaderMatrix(); gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer); gl.vertexAttribPointer(shaderProgram.attPosition, 3, gl.FLOAT, false, 8*4,0); gl.vertexAttribPointer(shaderProgram.attTexCoord, 2, gl.FLOAT, false, 8*4, 3*4); gl.vertexAttribPointer(shaderProgram.attNormal, 3, gl.FLOAT, false, 8*4, 5*4); gl.activeTexture(gl.TEXTURE0); gl.bindTexture(gl.TEXTURE_2D, myTexture); gl.uniform1i(shaderProgram.uniSampler, 0); gl.useProgram(shaderProgram); gl.drawArrays(gl.TRIANGLES, 0, vertexBuffer.numItems); //position cube 2 worldMatrix = mat4.create(); mvMatrix = mat4.create(); mat4.multiply(mvMatrix, worldMatrix, viewMatrix); mat4.translate(worldMatrix, worldMatrix, [40.0, 0.0, -30.0]); setShaderMatrix(); gl.drawArrays(gl.TRIANGLES, 0, vertexBuffer.numItems); //position cube 3 worldMatrix = mat4.create(); mvMatrix = mat4.create(); mat4.multiply(mvMatrix, worldMatrix, viewMatrix); mat4.translate(worldMatrix, worldMatrix, [20.0, 0.0, -100.0]); setShaderMatrix(); gl.drawArrays(gl.TRIANGLES, 0, vertexBuffer.numItems); camera.update();

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• First time shadow mapping problems

  - by user1294203

  I have implemented basic shadow mapping for the first time in OpenGL using shaders and I'm facing some problems. Below you can see an example of my rendered scene: The process of the shadow mapping I'm following is that I render the scene to the framebuffer using a View Matrix from the light point of view and the projection and model matrices used for normal rendering. In the second pass, I send the above MVP matrix from the light point of view to the vertex shader which transforms the position to light space. The fragment shader does the perspective divide and changes the position to texture coordinates. Here is my vertex shader, #version 150 core uniform mat4 ModelViewMatrix; uniform mat3 NormalMatrix; uniform mat4 MVPMatrix; uniform mat4 lightMVP; uniform float scale; in vec3 in_Position; in vec3 in_Normal; in vec2 in_TexCoord; smooth out vec3 pass_Normal; smooth out vec3 pass_Position; smooth out vec2 TexCoord; smooth out vec4 lightspace_Position; void main(void){ pass_Normal = NormalMatrix * in_Normal; pass_Position = (ModelViewMatrix * vec4(scale * in_Position, 1.0)).xyz; lightspace_Position = lightMVP * vec4(scale * in_Position, 1.0); TexCoord = in_TexCoord; gl_Position = MVPMatrix * vec4(scale * in_Position, 1.0); } And my fragment shader, #version 150 core struct Light{ vec3 direction; }; uniform Light light; uniform sampler2D inSampler; uniform sampler2D inShadowMap; smooth in vec3 pass_Normal; smooth in vec3 pass_Position; smooth in vec2 TexCoord; smooth in vec4 lightspace_Position; out vec4 out_Color; float CalcShadowFactor(vec4 lightspace_Position){ vec3 ProjectionCoords = lightspace_Position.xyz / lightspace_Position.w; vec2 UVCoords; UVCoords.x = 0.5 * ProjectionCoords.x + 0.5; UVCoords.y = 0.5 * ProjectionCoords.y + 0.5; float Depth = texture(inShadowMap, UVCoords).x; if(Depth < (ProjectionCoords.z + 0.001)) return 0.5; else return 1.0; } void main(void){ vec3 Normal = normalize(pass_Normal); vec3 light_Direction = -normalize(light.direction); vec3 camera_Direction = normalize(-pass_Position); vec3 half_vector = normalize(camera_Direction + light_Direction); float diffuse = max(0.2, dot(Normal, light_Direction)); vec3 temp_Color = diffuse * vec3(1.0); float specular = max( 0.0, dot( Normal, half_vector) ); float shadowFactor = CalcShadowFactor(lightspace_Position); if(diffuse != 0 && shadowFactor > 0.5){ float fspecular = pow(specular, 128.0); temp_Color += fspecular; } out_Color = vec4(shadowFactor * texture(inSampler, TexCoord).xyz * temp_Color, 1.0); } One of the problems is self shadowing as you can see in the picture, the crate has its own shadow cast on itself. What I have tried is enabling polygon offset (i.e. glEnable(POLYGON_OFFSET_FILL), glPolygonOffset(GLfloat, GLfloat) ) but it didn't change much. As you see in the fragment shader, I have put a static offset value of 0.001 but I have to change the value depending on the distance of the light to get more desirable effects , which not very handy. I also tried using front face culling when I render to the framebuffer, that didn't change much too. The other problem is that pixels outside the Light's view frustum get shaded. The only object that is supposed to be able to cast shadows is the crate. I guess I should pick more appropriate projection and view matrices, but I'm not sure how to do that. What are some common practices, should I pick an orthographic projection? From googling around a bit, I understand that these issues are not that trivial. Does anyone have any easy to implement solutions to these problems. Could you give me some additional tips? Please ask me if you need more information on my code. Here is a comparison with and without shadow mapping of a close-up of the crate. The self-shadowing is more visible.

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• Annoying flickering of vertices and edges (possible z-fighting)

  - by Belgin

  I'm trying to make a software z-buffer implementation, however, after I generate the z-buffer and proceed with the vertex culling, I get pretty severe discrepancies between the vertex depth and the depth of the buffer at their projected coordinates on the screen (i.e. zbuffer[v.xp][v.yp] != v.z, where xp and yp are the projected x and y coordinates of the vertex v), sometimes by a small fraction of a unit and sometimes by 2 or 3 units. Here's what I think is happening: Each triangle's data structure holds the plane's (that is defined by the triangle) coefficients (a, b, c, d) computed from its three vertices from their normal: void computeNormal(Vertex *v1, Vertex *v2, Vertex *v3, double *a, double *b, double *c) { double a1 = v1 -> x - v2 -> x; double a2 = v1 -> y - v2 -> y; double a3 = v1 -> z - v2 -> z; double b1 = v3 -> x - v2 -> x; double b2 = v3 -> y - v2 -> y; double b3 = v3 -> z - v2 -> z; *a = a2*b3 - a3*b2; *b = -(a1*b3 - a3*b1); *c = a1*b2 - a2*b1; } void computePlane(Poly *p) { double x = p -> verts[0] -> x; double y = p -> verts[0] -> y; double z = p -> verts[0] -> z; computeNormal(p -> verts[0], p -> verts[1], p -> verts[2], &p -> a, &p -> b, &p -> c); p -> d = p -> a * x + p -> b * y + p -> c * z; } The z-buffer just holds the smallest depth at the respective xy coordinate by somewhat casting rays to the polygon (I haven't quite got interpolation right yet so I'm using this slower method until I do) and determining the z coordinate from the reversed perspective projection formulas (which I got from here: double z = -(b*Ez*y + a*Ez*x - d*Ez)/(b*y + a*x + c*Ez - b*Ey - a*Ex); Where x and y are the pixel's coordinates on the screen; a, b, c, and d are the planes coefficients; Ex, Ey, and Ez are the eye's (camera's) coordinates. This last formula does not accurately give the exact vertices' z coordinate at their projected x and y coordinates on the screen, probably because of some floating point inaccuracy (i.e. I've seen it return something like 3.001 when the vertex's z-coordinate was actually 2.998). Here is the portion of code that hides the vertices that shouldn't be visible: for(i = 0; i < shape.nverts; ++i) { double dist = shape.verts[i].z; if(z_buffer[shape.verts[i].yp][shape.verts[i].xp].z < dist) shape.verts[i].visible = 0; else shape.verts[i].visible = 1; } How do I solve this issue? EDIT I've implemented the near and far planes of the frustum, with 24 bit accuracy, and now I have some questions: Is this what I have to do this in order to resolve the flickering? When I compare the z value of the vertex with the z value in the buffer, do I have to convert the z value of the vertex to z' using the formula, or do I convert the value in the buffer back to the original z, and how do I do that? What are some decent values for near and far? Thanks in advance.

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