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• Generating geometry when using VBO

  - by onedayitwillmake

  Currently I am working on a project in which I generate geometry based on the players movement. A glorified very long trail, composed of quads. I am doing this by storing a STD::Vector, and removing the oldest verticies once enough exist, and then calling glDrawArrays. I am interested in switching to a shader based model, usually examples I see the VBO is generated at start and then that's basically it. What is the best route to go about creating geometry in real time, using shader / VBO approach

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• OpenGL Tessellation makes point

  - by urza57

  A little problem with my tessellation shader. I try to implement a simple tessellation shader but it only makes points. Here's my vertex shader : out vec4 ecPosition; out vec3 ecNormal; void main( void ) { vec4 position = gl_Vertex; gl_Position = gl_ModelViewProjectionMatrix * position; ecPosition = gl_ModelViewMatrix * position; ecNormal = normalize(gl_NormalMatrix * gl_Normal); } My tessellation control shader : layout(vertices = 3) out; out vec4 ecPosition3[]; in vec3 ecNormal[]; in vec4 ecPosition[]; out vec3 myNormal[]; void main() { gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position; myNormal[gl_InvocationID] = ecNormal[gl_InvocationID]; ecPosition3[gl_InvocationID] = ecPosition[gl_InvocationID]; gl_TessLevelOuter[0] = float(4.0); gl_TessLevelOuter[1] = float(4.0); gl_TessLevelOuter[2] = float(4.0); gl_TessLevelInner[0] = float(4.0); } And my Tessellation Evaluation shader: layout(triangles, equal_spacing, ccw) in; in vec3 myNormal[]; in vec4 ecPosition3[]; out vec3 ecNormal; out vec4 ecPosition; void main() { float u = gl_TessCoord.x; float v = gl_TessCoord.y; float w = gl_TessCoord.z; vec3 position = vec4(gl_in[0].gl_Position.xyz * u + gl_in[1].gl_Position.xyz * v + gl_in[2].gl_Position.xyz * w ); vec3 position2 = vec4(ecPosition3[0].xyz * u + ecPosition3[1].xyz * v + ecPosition3[2].xyz * w ); vec3 normal = myNormal[0] * u + myNormal[1] * v + myNormal[2] * w ); ecNormal = normal; gl_Position = vec4(position, 1.0); ecPosition = vec4(position2, 1.0); } Thank you !

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• GLSL Shader Texture Performance

  - by Austin

  I currently have a project that renders OpenGL video using a vertex and fragment shader. The shaders work fine as-is, but in trying to add in texturing, I am running into performance issues and can't figure out why. Before adding texturing, my program ran just fine and loaded my CPU between 0%-4%. When adding texturing (specifically textures AND color -- noted by comment below), my CPU is 100% loaded. The only code I have added is the relevant texturing code to the shader, and the "glBindTexture()" calls to the rendering code. Here are my shaders and relevant rending code. Vertex Shader: #version 150 uniform mat4 mvMatrix; uniform mat4 mvpMatrix; uniform mat3 normalMatrix; uniform vec4 lightPosition; uniform float diffuseValue; layout(location = 0) in vec3 vertex; layout(location = 1) in vec3 color; layout(location = 2) in vec3 normal; layout(location = 3) in vec2 texCoord; smooth out VertData { vec3 color; vec3 normal; vec3 toLight; float diffuseValue; vec2 texCoord; } VertOut; void main(void) { gl_Position = mvpMatrix * vec4(vertex, 1.0); VertOut.normal = normalize(normalMatrix * normal); VertOut.toLight = normalize(vec3(mvMatrix * lightPosition - gl_Position)); VertOut.color = color; VertOut.diffuseValue = diffuseValue; VertOut.texCoord = texCoord; } Fragment Shader: #version 150 smooth in VertData { vec3 color; vec3 normal; vec3 toLight; float diffuseValue; vec2 texCoord; } VertIn; uniform sampler2D tex; layout(location = 0) out vec3 colorOut; void main(void) { float diffuseComp = max( dot(normalize(VertIn.normal), normalize(VertIn.toLight)) ), 0.0); vec4 color = texture2D(tex, VertIn.texCoord); colorOut = color.rgb * diffuseComp * VertIn.diffuseValue + color.rgb * (1 - VertIn.diffuseValue); // FOLLOWING LINE CAUSES PERFORMANCE ISSUES colorOut *= VertIn.color; } Relevant Rendering Code: // 3 textures have been successfully pre-loaded, and can be used // texture[0] is a 1x1 white texture to effectively turn off texturing glUseProgram(program); // Draw squares glBindTexture(GL_TEXTURE_2D, texture[1]); // Set attributes, uniforms, etc glDrawArrays(GL_QUADS, 0, 6*4); // Draw triangles glBindTexture(GL_TEXTURE_2D, texture[0]); // Set attributes, uniforms, etc glDrawArrays(GL_TRIANGLES, 0, 3*4); // Draw reference planes glBindTexture(GL_TEXTURE_2D, texture[0]); // Set attributes, uniforms, etc glDrawArrays(GL_LINES, 0, 4*81*2); // Draw terrain glBindTexture(GL_TEXTURE_2D, texture[2]); // Set attributes, uniforms, etc glDrawArrays(GL_TRIANGLES, 0, 501*501*6); // Release glBindTexture(GL_TEXTURE_2D, 0); glUseProgram(0); Any help is greatly appreciated!

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• Open Source Errors on Apple Cruch

  - by BluFire

  I've been looking around and I finally got the full source code called Apple-Crunch from google code. But when I put it into my project, the source code included so many errors in the class files such as: cannot be resolved into a type the constructor is undefined the method method() is undefined for the type Sprite class.java I downloaded the source directly from the command-line and noticed errors popping up on my project. Since i couldn't figure out how to import the actual folder into my workspace(it wouldn't show up on existing projects) I decided to copy and overwrite the folders into the project. The Errors were still there so I looked at the class files and noticed that the classes with errors extended from 'RokonActivity'. I then proceeded to add to the libs folder the rokon library in hopes to fix the errors. Sadly it didn't work and now I don't what to do to fix the errors. How do i fix the errors without having to manually change the code? The source code should be fully functional so why is there errors?

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• Render an image with separate layers for shadows/reflections in 3D Studio Max?

  - by Bernd Plontsch

  I have a scene with a simple object standing on a ground in the center. Caused by lights and the ground material there is some shadow and reflection on the ground surrounding the object. How can I render an image containing 3 separate layers for the object the ground the reflection / shadow on the ground Which format to use for this (it should include all 3 layers + I should be able to enable/disable them in Photoshop)? How do I define or prepare those layers for being rendering as image layers?

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• Need help about Drag a sprite with Animation (Cocos2d)

  - by Zishan

  I want to play an animation when someone drag a sprite from it's default position to another selected position. If he drag half of the selected position then animation will be play half. Example, I have 15 Frames of a animation and have a projectile arm. The projectile arm can be rotate maximum 30°, if someone rotate the arm 2° then animation sprite will be show 2nd frame, if rotate 12° then animation sprite will be show 6th frame.... and so on. Also when he release the arm, then the arm will be reverse back to it's default position and animation frames also will be reverse back to it's default first frame. I am new on cocos2d.I know how to make an animation and how to drag a sprite but I have no idea how to do this. Can anyone Please give me any idea or any tutorial how to do this, it will be very helpful for me. Thank you in advance.

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• TileMapRenderer in libGDX not drawing anything

  - by Benjamin Dengler

  So I followed the tutorial on the libGDX wiki to draw Tiled maps but it doesn't seem to render anything. Here's how I setup my OrthographicCamera and load the map: camera = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight()); map = TiledLoader.createMap(Gdx.files.internal("maps/test.tmx")); atlas = new TileAtlas(map, Gdx.files.internal("maps")); tileMapRenderer = new TileMapRenderer(map, atlas, 8, 8); And here is my render function: Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); camera.update(); tileMapRenderer.render(camera); Also I did pack the tile map using the TiledMapPacker. I'm completely stumped... am I missing anything obvious here? EDIT: While debugging I noticed that the TileAtlas seems to be empty, which I guess shouldn't be the case, but I have no idea why it's empty.

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• How should I do 3D games through Java on a mac?

  - by Steven Rogers

  I have been self-teaching myself Java on the mac mostly because the language is cross-platform. Recently, I have been only able to develop 2D games using the Graphics2D class. Now, I want to learn how to make 3D games in Java. I used to model and animate stuff in 3D, so my knowledge of 3-Dimensional stuff is okay. I have spent the last 3 hours using google to look up ways of making 3D games in java. Apparently the best one to use is OpenGL, so i looked up a tutorial on it and i cannot find a tutorial that shows how to (if there is a way) install JOGL on the Mac platform. Should i continue to use Java? How can i make 3D games using Java? What is the best way to make 3D games on a mac?

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• Is it possible to construct a cube with fewer than 24 vertices

  - by Telanor

  I have a cube-based world like Minecraft and I'm wondering if there's a way to construct a cube with fewer than 24 vertices so I can reduce memory usage. It doesn't seem possible to me for 2 reasons: the normals wouldn't come out right and per-face textures wouldn't work. Is this the case or am I wrong? Maybe there's some fancy new DX11 tech that can help? Edit: Just to clarify, I have 2 requirements: I need surface normals for each cube face in order to do proper lighting and I need a way to address a different indexes in a texture array for each cube face

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• Who owns the intellectual property to Fragile Allegiance?

  - by analytik

  Fragile Allegiance was developed by Gremlin Interactive, which was later acquired by Infogrames (Atari). I couldn't find any details of the acquisition though. The only interesting thing I have found online is that the owner of the registered trademark Fragile Allegiance is Interplay, who published Fragile Allegiance. However, the only copyright note I've found was in one installation .ini file, claiming it for Gremlin. What are the common business practices when it comes to old, unused IPs? What do publishers/developers actually need to legally claim an intellectual property? Does anyone have an experience with contacting big publishers with copyright/IP inquiries? Related legal question.

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• Light following me around the room. Something is wrong with my shader!

  - by Robinson

  I'm trying to do a spot (Blinn) light, with falloff and attenuation. It seems to be working OK except I have a bit of a space problem. That is, whenever I move the camera the light moves to maintain the same relative position, rather than changing with the camera. This results in the light moving around, i.e. not always falling on the same surfaces. It's as if there's a flashlight attached to the camera. I'm transforming the lights beforehand into view space, so Light_Position and Light_Direction are already in eye space (I hope!). I made a little movie of what it looks like here: My camera rotating around a point inside a box. The light is fixed in the centre up and its "look at" point in a fixed position in front of it. As you can see, as the camera rotates around the origin (always looking at the centre), so don't think the box is rotating (!). The lighting follows it around. To start, some code. This is how I'm transforming the light into view space (it gets passed into the shader already in view space): // Compute eye-space light position. Math::Vector3d eyeSpacePosition = MyCamera->ViewMatrix() * MyLightPosition; MyShaderVariables->Set(MyLightPositionIndex, eyeSpacePosition); // Compute eye-space light direction vector. Math::Vector3d eyeSpaceDirection = Math::Unit(MyLightLookAt - MyLightPosition); MyCamera->ViewMatrixInverseTranspose().TransformNormal(eyeSpaceDirection); MyShaderVariables->Set(MyLightDirectionIndex, eyeSpaceDirection); Can anyone give me a clue as to what I'm doing wrong here? I think the light should remain looking at a fixed point on the box, regardless of the camera orientation. Here are the vertex and pixel shaders: /////////////////////////////////////////////////// // Vertex Shader /////////////////////////////////////////////////// #version 420 /////////////////////////////////////////////////// // Uniform Buffer Structures /////////////////////////////////////////////////// // Camera. layout (std140) uniform Camera { mat4 Camera_View; mat4 Camera_ViewInverseTranspose; mat4 Camera_Projection; }; // Matrices per model. layout (std140) uniform Model { mat4 Model_World; mat4 Model_WorldView; mat4 Model_WorldViewInverseTranspose; mat4 Model_WorldViewProjection; }; // Spotlight. layout (std140) uniform OmniLight { float Light_Intensity; vec3 Light_Position; vec3 Light_Direction; vec4 Light_Ambient_Colour; vec4 Light_Diffuse_Colour; vec4 Light_Specular_Colour; float Light_Attenuation_Min; float Light_Attenuation_Max; float Light_Cone_Min; float Light_Cone_Max; }; /////////////////////////////////////////////////// // Streams (per vertex) /////////////////////////////////////////////////// layout(location = 0) in vec3 attrib_Position; layout(location = 1) in vec3 attrib_Normal; layout(location = 2) in vec3 attrib_Tangent; layout(location = 3) in vec3 attrib_BiNormal; layout(location = 4) in vec2 attrib_Texture; /////////////////////////////////////////////////// // Output streams (per vertex) /////////////////////////////////////////////////// out vec3 attrib_Fragment_Normal; out vec4 attrib_Fragment_Position; out vec2 attrib_Fragment_Texture; out vec3 attrib_Fragment_Light; out vec3 attrib_Fragment_Eye; /////////////////////////////////////////////////// // Main /////////////////////////////////////////////////// void main() { // Transform normal into eye space attrib_Fragment_Normal = (Model_WorldViewInverseTranspose * vec4(attrib_Normal, 0.0)).xyz; // Transform vertex into eye space (world * view * vertex = eye) vec4 position = Model_WorldView * vec4(attrib_Position, 1.0); // Compute vector from eye space vertex to light (light is in eye space already) attrib_Fragment_Light = Light_Position - position.xyz; // Compute vector from the vertex to the eye (which is now at the origin). attrib_Fragment_Eye = -position.xyz; // Output texture coord. attrib_Fragment_Texture = attrib_Texture; // Compute vertex position by applying camera projection. gl_Position = Camera_Projection * position; } and the pixel shader: /////////////////////////////////////////////////// // Pixel Shader /////////////////////////////////////////////////// #version 420 /////////////////////////////////////////////////// // Samplers /////////////////////////////////////////////////// uniform sampler2D Map_Diffuse; /////////////////////////////////////////////////// // Global Uniforms /////////////////////////////////////////////////// // Material. layout (std140) uniform Material { vec4 Material_Ambient_Colour; vec4 Material_Diffuse_Colour; vec4 Material_Specular_Colour; vec4 Material_Emissive_Colour; float Material_Shininess; float Material_Strength; }; // Spotlight. layout (std140) uniform OmniLight { float Light_Intensity; vec3 Light_Position; vec3 Light_Direction; vec4 Light_Ambient_Colour; vec4 Light_Diffuse_Colour; vec4 Light_Specular_Colour; float Light_Attenuation_Min; float Light_Attenuation_Max; float Light_Cone_Min; float Light_Cone_Max; }; /////////////////////////////////////////////////// // Input streams (per vertex) /////////////////////////////////////////////////// in vec3 attrib_Fragment_Normal; in vec3 attrib_Fragment_Position; in vec2 attrib_Fragment_Texture; in vec3 attrib_Fragment_Light; in vec3 attrib_Fragment_Eye; /////////////////////////////////////////////////// // Result /////////////////////////////////////////////////// out vec4 Out_Colour; /////////////////////////////////////////////////// // Main /////////////////////////////////////////////////// void main(void) { // Compute N dot L. vec3 N = normalize(attrib_Fragment_Normal); vec3 L = normalize(attrib_Fragment_Light); vec3 E = normalize(attrib_Fragment_Eye); vec3 H = normalize(L + E); float NdotL = clamp(dot(L,N), 0.0, 1.0); float NdotH = clamp(dot(N,H), 0.0, 1.0); // Compute ambient term. vec4 ambient = Material_Ambient_Colour * Light_Ambient_Colour; // Diffuse. vec4 diffuse = texture2D(Map_Diffuse, attrib_Fragment_Texture) * Light_Diffuse_Colour * Material_Diffuse_Colour * NdotL; // Specular. float specularIntensity = pow(NdotH, Material_Shininess) * Material_Strength; vec4 specular = Light_Specular_Colour * Material_Specular_Colour * specularIntensity; // Light attenuation (so we don't have to use 1 - x, we step between Max and Min). float d = length(-attrib_Fragment_Light); float attenuation = smoothstep(Light_Attenuation_Max, Light_Attenuation_Min, d); // Adjust attenuation based on light cone. float LdotS = dot(-L, Light_Direction), CosI = Light_Cone_Min - Light_Cone_Max; attenuation *= clamp((LdotS - Light_Cone_Max) / CosI, 0.0, 1.0); // Final colour. Out_Colour = (ambient + diffuse + specular) * Light_Intensity * attenuation; }

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• Pathfinding in multi goal, multi agent environment

  - by Rohan Agrawal

  I have an environment in which I have multiple agents (a), multiple goals (g) and obstacles (o). . . . a o . . . . . . . o . g . . a . . . . . . . . . . o . . . . o o o o . g . . o . . . . . . . o . . . . o . . . . o o o o a What would an appropriate algorithm for pathfinding in this environment? The only thing I can think of right now, is to Run a separate version of A* for each goal separately, but i don't think that's very efficient.

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• HLSL - Creating Shadows in 2D

  - by richard

  The way that I create shadows is by the following technique: http://www.catalinzima.com/2010/07/my-technique-for-the-shader-based-dynamic-2d-shadows/ But I have questions to HLSL. The way that I currently do it is, I have a black and white image, where Black means 'object', and white means 'nothing'. I then distort the image like in the tutorial. I do this with a pixel shader, but instead of rendering to the screen, I render to a texture, back to my application. I then take this, and create the shadows, and then send it back to the graphics card to undo the distortion, after the shadow has been added - this comes back and I have a stencil of shadow. I can put this ontop of the original image and send them back to the graphics card, which then puts them on the screen. To me this is alot of back and forth. Is there a way i can avoid this? The problem that I am having is that I need to basically go through all positions in the texture 3 times, and use the new new texture every time instead of the orginal one. I tried to read up on Passes, but i don't think that i am heading in the right direction there. Help?

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• Physics timestep questions

  - by SSL

  I've got a projectile working perfectly using the code below: //initialised in loading screen 60 is the FPS - projectilEposition and velocity are Vector3 types gravity = new Vector3(0, -(float)9.81 / 60, 0); //called every frame projectilePosition += projectileVelocity; This seems to work fine but I've noticed in various projectile examples I've seen that the elapsedtime per update is taken into account. What's the difference between the two and how can I convert the above to take into account the elapsedtime? (I'm using XNA - do I use ElapsedTime.TotalSeconds or TotalMilliseconds)? Edit: Forgot to add my attempt at using elapsedtime, which seemed to break the physics: projectileVelocity.Y += -(float)((9.81 * gameTime.ElapsedGameTime.TotalSeconds * gameTime.ElapsedGameTime.TotalSeconds) * 0.5f); Thanks for the help

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• 2D object-aligned bounding-box intersection test

  - by AshleysBrain

  Hi all, I have two object-aligned bounding boxes (i.e. not axis aligned, they rotate with the object). I'd like to know if two object-aligned boxes overlap. (Edit: note - I'm using an axis-aligned bounding box test to quickly discard distant objects, so it doesn't matter if the quad routine is a little slower.) My boxes are stored as four x,y points. I've searched around for answers, but I can't make sense of the variable names and algorithms in examples to apply them to my particular case. Can someone help show me how this would be done, in a clear and simple way? Thanks. (The particular language isn't important, C-style pseudo code is OK.)

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• Draw multiple objects with textures

  - by Simplex

  I want to draw cubes using textures. void OperateWithMainMatrix(ESContext* esContext, GLfloat offsetX, GLfloat offsetY, GLfloat offsetZ) { UserData *userData = (UserData*) esContext->userData; ESMatrix modelview; ESMatrix perspective; //Manipulation with matrix ... glVertexAttribPointer(userData->positionLoc, 3, GL_FLOAT, GL_FALSE, 0, cubeFaces); //in cubeFaces coordinates verticles cube glVertexAttribPointer(userData->normalLoc, 3, GL_FLOAT, GL_FALSE, 0, cubeFaces); //for normals (use in fragment shaider for textures) glEnableVertexAttribArray(userData->positionLoc); glEnableVertexAttribArray(userData->normalLoc); // Load the MVP matrix glUniformMatrix4fv(userData->mvpLoc, 1, GL_FALSE, (GLfloat*)&userData->mvpMatrix.m[0][0]); //Bind base map glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_CUBE_MAP, userData->baseMapTexId); //Set the base map sampler to texture unit to 0 glUniform1i(userData->baseMapLoc, 0); // Draw the cube glDrawArrays(GL_TRIANGLES, 0, 36); } (coordinates transformation is in OperateWithMainMatrix() ) Then Draw() function is called: void Draw(ESContext *esContext) { UserData *userData = esContext->userData; // Set the viewport glViewport(0, 0, esContext->width, esContext->height); // Clear the color buffer glClear(GL_COLOR_BUFFER_BIT); // Use the program object glUseProgram(userData->programObject); OperateWithMainMatrix(esContext, 0.0f, 0.0f, 0.0f); eglSwapBuffers(esContext->eglDisplay, esContext->eglSurface); } This work fine, but if I try to draw multiple cubes (next code for example): void Draw(ESContext *esContext) { ... // Use the program object glUseProgram(userData->programObject); OperateWithMainMatrix(esContext, 2.0f, 0.0f, 0.0f); OperateWithMainMatrix(esContext, 1.0f, 0.0f, 0.0f); OperateWithMainMatrix(esContext, 0.0f, 0.0f, 0.0f); OperateWithMainMatrix(esContext, -1.0f, 0.0f, 0.0f); OperateWithMainMatrix(esContext, -2.0f, 0.0f, 0.0f); eglSwapBuffers(esContext->eglDisplay, esContext->eglSurface); } A side faces overlapes frontal face. The side face of the right cube overlaps frontal face of the center cube. How can i remove this effect and display miltiple cubes without it?

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• Bullet Physic: Transform body after adding

  - by Mathias Hölzl

  I would like to transform a rigidbody after adding it to the btDiscreteDynamicsWorld. When I use the CF_KINEMATIC_OBJECT flag I am able to transform it but it's static (no collision response/gravity). When I don't use the CF_KINEMATIC_OBJECT flag the transform doesn't gets applied. So how to I transform non-static objects in bullet? DemoCode: btBoxShape* colShape = new btBoxShape(btVector3(SCALING*1,SCALING*1,SCALING*1)); /// Create Dynamic Objects btTransform startTransform; startTransform.setIdentity(); btScalar mass(1.f); //rigidbody is dynamic if and only if mass is non zero, otherwise static bool isDynamic = (mass != 0.f); btVector3 localInertia(0,0,0); if (isDynamic) colShape->calculateLocalInertia(mass,localInertia); btDefaultMotionState* myMotionState = new btDefaultMotionState(); btRigidBody::btRigidBodyConstructionInfo rbInfo(mass,myMotionState,colShape,localInertia); btRigidBody* body = new btRigidBody(rbInfo); body->setCollisionFlags(body->getCollisionFlags()|btCollisionObject::CF_KINEMATIC_OBJECT); body->setActivationState(DISABLE_DEACTIVATION); m_dynamicsWorld->addRigidBody(body); startTransform.setOrigin(SCALING*btVector3( btScalar(0), btScalar(20), btScalar(0) )); body->getMotionState()->setWorldTransform(startTransform);

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• Mesh with quads to triangle mesh

  - by scape

  I want to use Blender for making models yet realize some of the polygons are not triangles but contain quads or more (example: cylinder top and bottom). I could export the the mesh as a basic mesh file and import it in to an openGL application and workout rendering the quads as tris, but anything with more than 4 vert indices is beyond me. Is it typical to convert the mesh to a triangle-based mesh inside blender before exporting it? I actually tried this through the quads_convert_to_tris method within a blender py script and the top of the cylinder does not look symmetrical. What is typically done to render a loaded mesh as a tri?

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• Where to store shaders

  - by Mark Ingram

  I have an OpenGL renderer which has a Scene member variable. The Scene object can contain N SceneObjects. I use these SceneObjects for storing the vertex position and any transforms. My question is, where should shaders be stored in this arrangement? I guess they need to be in a central location because multiple objects can use the same shader. But then each object needs access to the shader because it needs to set attributes into the shader. Does anyone have any advice?

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• Painting with pixel shaders

  - by Gustavo Maciel

  I have an almost full understanding of how 2D Lighting works, saw this post and was tempted to try implementing this in HLSL. I planned to paint each of the layers with shaders, and then, combine them just drawing one on top of another, or just pass the 3 textures to the shader and getting a better way to combine them. Working almost as planned, but I got a little question in the matter. I'm drawing each layer this way: GraphicsDevice.SetRenderTarget(lighting); GraphicsDevice.Clear(Color.Transparent); //... Setup shader SpriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullNone, lightingShader); SpriteBatch.Draw(texture, fullscreen, Color.White); SpriteBatch.End(); GraphicsDevice.SetRenderTarget(darkMask); GraphicsDevice.Clear(Color.Transparent); //... Setup shader SpriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.LinearClamp, DepthStencilState.None, RasterizerState.CullNone, darkMaskShader); SpriteBatch.Draw(texture, fullscreen, Color.White); SpriteBatch.End(); Where lightingShader and darkMaskShader are shaders that, with parameters (view and proj matrices, light pos, color and range, etc) generate a texture meant to be that layer. It works fine, but I'm not sure if drawing a transparent quad on top of a transparent render target is the best way of doing it. Because I actually just need the position and params. Concluding: Can I paint a texture with shaders without having to clear it and then draw a transparent texture on top of it?

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• 3D BSP rendering for maps made in 2d platform style

  - by Dev Joy

  I wish to render a 3D map which is always seen from top, camera is in sky and always looking at earth. Sample of a floor layout: I don't think I need complex structures like BSP trees to render them. I mean I can divide the map in grids and render them like done in 2D platform games. I just want to know if this is a good idea and what may go wrong if I don't choose a BSP tree rendering here. Please also mention is any better known rendering techniques are available for such situations.

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• Narrow-phase collision detection algorithms

  - by Marian Ivanov

  There are three phases of collision detection. Broadphase: It loops between all objecs that can interact, false positives are allowed, if it would speed up the loop. Narrowphase: Determines whether they collide, and sometimes, how, no false positives Resolution: Resolves the collision. The question I'm asking is about the narrowphase. There are multiple algorithms, differing in complexity and accuracy. Hitbox intersection: This is an a-posteriori algorithm, that has the lowest complexity, but also isn't too accurate, Color intersection: Hitbox intersection for each pixel, a-posteriori, pixel-perfect, not accuratee in regards to time, higher complexity Separating axis theorem: This is used more often, accurate for triangles, however, a-posteriori, as it can't find the edge, when taking last frame in account, it's more stable Linear raycasting: A-priori algorithm, useful for semi-realistic-looking physics, finds the intersection point, even more accurate than SAT, but with more complexity Spline interpolation: A-priori, even more accurate than linear rays, even more coplexity. There are probably many more that I've forgot about. The question is, in when is it better to use SAT, when rays, when splines, and whether there is anything better.

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• Looking for literature about graphics pipeline optimization

  - by zacharmarz

  I am looking for some books, articles or tutorials about graphics architecture and graphics pipeline optimizations. It shouldn't be too old (2008 or newer) - the newer, the better. I have found something in [Optimising the Graphics Pipeline, NVIDIA, Koji Ashida] - too old, [Real-time rendering, Akenine Moller], [OpenGL Bindless Extensions, NVIDIA, Jeff Bolz], [Efficient multifragment effects on graphics processing units, Louis Frederic Bavoil] and some internet discussions. But there is not too much information and I want to read more. It should contain something about application, driver, memory and shader units communication and data transfers. About vertices and attributes. Also pre and post T&L cache (if they still exist in nowadays architectures) etc. I don't need anything about textures, frame buffers and rasterization. It can also be about OpenGL (not about DirecX) and optimizing extensions (not old extensions like VBOs, but newer like vertex_buffer_unified_memory).

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• Robust line of sight test on the inside of a polygon with tolerance

  - by David Gouveia

  Foreword This is a followup to this question and the main problem I'm trying to solve. My current solution is an hack which involves inflating the polygon, and doing most calculations on the inflated polygon instead. My goal is to remove this step completely, and correctly solve the problem with calculations only. Problem Given a concave polygon and treating all of its edges as if they were walls in a level, determine whether two points A and B are in line of sight of each other, while accounting for some degree of floating point errors. I'm currently basing my solution on a series of line-segment interection tests. In other words: If any of the end points are outside the polygon, they are not in line of sight. If both end points are inside the polygon, and the line segment from A to B crosses any of the edges from the polygon, then they are not in line of sight. If both end points are inside the polygon, and the line segment from A to B does not cross any of the edges from the polygon, then they are in line of sight. But the problem is dealing correctly with all the edge cases. In particular, it must be able to deal with all the situations depicted below, where red lines are examples that should be rejected, and green lines are examples that should be accepted. I probably missed a few other situations, such as when the line segment from A to B is colinear with an edge, but one of the end points is outside the polygon. One point of particular interest is the difference between 1 and 9. In both cases, both end points are vertices of the polygon, and there are no edges being intersected, but 1 should be rejected while 9 should be accepted. How to distinguish these two? I could check some middle point within the segment to see if it falls inside or not, but it's easy to come up with situations in which it would fail. Point 7 was also pretty tricky and I had to to treat it as a special case, which checks if two points are adjacent vertices of the polygon directly. But there are also other chances of line segments being col linear with the edges of the polygon, and I'm still not entirely sure how I should handle those cases. Is there any well known solution to this problem?

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• Meaning of offset in pygame Mask.overlap methods

  - by Alan

  I have a situation in which two rectangles collide, and I have to detect how much did they collide so so I can redraw the objects in a way that they are only touching each others edges. It's a situation in which a moving ball should hit a completely unmovable wall and instantly stop moving. Since the ball sometimes moves multiple pixels per screen refresh, it it possible that it enters the wall with more that half its surface when the collision is detected, in which case i want to shift it position back to the point where it only touches the edges of the wall. Here is the conceptual image it: I decided to implement this with masks, and thought that i could supply the masks of both objects (wall and ball) and get the surface (as a square) of their intersection. However, there is also the offset parameter which i don't understand. Here are the docs for the method: Mask.overlap Returns the point of intersection if the masks overlap with the given offset - or None if it does not overlap. Mask.overlap(othermask, offset) -> x,y The overlap tests uses the following offsets (which may be negative): +----+----------.. |A | yoffset | +-+----------.. +--|B |xoffset | | : :

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