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• WIn API Basic Paint program

  - by Tom Burman

  Just trying to learn a bit of Win API. Im trying to make a basic drawing app, a bit like MS Paint. For the time being im trying to get one function to work which is, when you left click and drag the mouse around the screen a line is drawn behind the mouse. Heres what i have so far, but for some reason: 1) the line starts drawing straight away rather then waiting for the left click 2) the line isn't solid its very dotty. case WM_MOUSEMOVE: { if(MK_LBUTTON){ hdc = GetDC(hwnd); hPen = CreatePen(PS_SOLID,5,RGB(0, 0, 255)); SelectObject(hdc, hPen); int x = LOWORD(lParam); int y = HIWORD(lParam); MoveToEx(hdc,x,y,NULL); LineTo(hdc, LOWORD(lParam), HIWORD(lParam)); ReleaseDC(hwnd,hdc); } else break; } } Thanks for any help!

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• Sprites, Primitives and logic entity as structs

  - by Jeffrey

  I'm wondering would it be considered acceptable: The window class is responsible for drawing data, so it will have a method: Window::draw(const Sprite&); Window::draw(const Rect&); Window::draw(const Triangle&); Window::draw(const Circle&); and all those primitives + sprites would be just public struct. For example Sprite: struct Sprite { float x, y; // center float origin_x, origin_y; float width, height; float rotation; float scaling; GLuint texture; Sprite(float w, float h); Sprite(float w, float h, float a, float b); void useTexture(std::string file); void setOrigin(float a, float b); void move(float a, float b); // relative move void moveTo(float a, float b); // absolute move void rotate(float a); // relative rotation void rotateTo(float a); // absolute rotation void rotationReset(); void scale(float a); // relative scaling void scaleTo(float a); // absolute scaling void scaleReset(); }; So instead of having each primitive to call their draw() function, which is a little bit off topic for their object, I let the Window class handle all the OpenGL stuff and manipulate them as simple objects that will be drawn later on. Is this pattern used? Does it have any cons against it's primitives-draw-themself pattern? Are there any other related patterns?

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• Can't get sprite to rotate correctly?

  - by rphello101

  I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was to keep track of the angle the sprite is at since I have to multiply the cosine/sine of the angle by the move speed in order to get the sprite to go "forwards" even if it is, say, facing 45 degrees in quadrant 3. However, before I even worry about that, I'm having trouble even getting my sprite to rotate in the first place. Preliminary console tests showed that this code worked, but when applied to the sprite, it just kind twitches. Anyone know what's wrong? int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x; int pY = sprite.y; int tempY, tempX; double mAng, pAng = sprite.angle; double angRotate=0; if(mX!=pX){ tempY=pY-mY; tempX=mX-pX; mAng = Math.toDegrees(Math.atan2(Math.abs((tempY)),Math.abs((tempX)))); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=270; else mAng=90; } //Calculations if(mX<pX&&mY<pY){ //If in Q2 mAng = 180-mAng; } if(mX<pX&&mY>pY){ //If in Q3 mAng = 180+mAng; } if(mX>pX&&mY>pY){ //If in Q4 mAng = 360-mAng; } angRotate = mAng-pAng; sprite.angle = mAng; sprite.image.setRotation((float)angRotate);

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• Unity Occlusion Portals: What and How?

  - by Nick Wiggill

  (Here I eat my words on Meta about posting Unity questions on Unity Answers... since that site is less responsive than this one.) Unity provides cell-based Occlusion Culling (via Umbra, I believe). However, a newer feature that it supports is Occlusion Portals. The question is, if BSP-based occlusion culling is already a feature of Unity, what do portals add, and how? PS. This question is not "What are portals?" -- I'm aware of the original Quake BSP-style portals -- which is partly why I find the explicit portal concept in Unity odd, since it uses BSP anyway.

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• Correct use of VAO's in OpenGL ES2 for iOS?

  - by sak

  I'm migrating to OpenGL ES2 for one of my iOS projects, and I'm having trouble to get any geometry to render successfully. Here's where I'm setting up the VAO rendering: void bindVAO(int vertexCount, struct Vertex* vertexData, GLushort* indexData, GLuint* vaoId, GLuint* indexId){ //generate the VAO & bind glGenVertexArraysOES(1, vaoId); glBindVertexArrayOES(*vaoId); GLuint positionBufferId; //generate the VBO & bind glGenBuffers(1, &positionBufferId); glBindBuffer(GL_ARRAY_BUFFER, positionBufferId); //populate the buffer data glBufferData(GL_ARRAY_BUFFER, vertexCount, vertexData, GL_STATIC_DRAW); //size of verte position GLsizei posTypeSize = sizeof(kPositionVertexType); glVertexAttribPointer(kVertexPositionAttributeLocation, kVertexSize, kPositionVertexTypeEnum, GL_FALSE, sizeof(struct Vertex), (void*)offsetof(struct Vertex, position)); glEnableVertexAttribArray(kVertexPositionAttributeLocation); //create & bind index information glGenBuffers(1, indexId); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, *indexId); glBufferData(GL_ELEMENT_ARRAY_BUFFER, vertexCount, indexData, GL_STATIC_DRAW); //restore default state glBindVertexArrayOES(0); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); glBindBuffer(GL_ARRAY_BUFFER, 0); } And here's the rendering step: //bind the frame buffer for drawing glBindFramebuffer(GL_FRAMEBUFFER, outputFrameBuffer); glClear(GL_COLOR_BUFFER_BIT); //use the shader program glUseProgram(program); glClearColor(0.4, 0.5, 0.6, 0.5); float aspect = fabsf(320.0 / 480.0); GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(GLKMathDegreesToRadians(65.0f), aspect, 0.1f, 100.0f); GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -1.0f); GLKMatrix4 mvpMatrix = GLKMatrix4Multiply(projectionMatrix, modelViewMatrix); //glUniformMatrix4fv(projectionMatrixUniformLocation, 1, GL_FALSE, projectionMatrix.m); glUniformMatrix4fv(modelViewMatrixUniformLocation, 1, GL_FALSE, mvpMatrix.m); glBindVertexArrayOES(vaoId); glDrawElements(GL_TRIANGLE_FAN, kVertexCount, GL_FLOAT, &indexId); //bind the color buffer glBindRenderbuffer(GL_RENDERBUFFER, colorRenderBuffer); [context presentRenderbuffer:GL_RENDERBUFFER]; The screen is rendering the color passed to glClearColor correctly, but not the shape passed into bindVAO. Is my VAO being built correctly? Thanks!

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• DX9 Deferred Rendering, GBuffer displays as clear color only

  - by Fire31

  I'm trying to implement Catalin Zima's Deferred Renderer in a very lightweight c++ DirectX 9 app (only renders a skydome and a model), at this moment I'm trying to render the gbuffer, but I'm having a problem, the screen shows only the clear color, no matter how much I move the camera around. However, removing all the render target operations lets the app render the scene normally, even if the models are being applied the renderGBuffer effect. Any ideas of what I'm doing wrong?

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• Hardware instancing for voxel engine

  - by Menno Gouw

  i just did the tutorial on Hardware Instancing from this source: http://www.float4x4.net/index.php/2011/07/hardware-instancing-for-pc-in-xna-4-with-textures/. Somewhere between 900.000 and 1.000.000 draw calls for the cube i get this error "XNA Framework HiDef profile supports a maximum VertexBuffer size of 67108863." while still running smoothly on 900k. That is slightly less then 100x100x100 which are a exactly a million. Now i have seen voxel engines with very "tiny" voxels, you easily get to 1.000.000 cubes in view with rough terrain and a decent far plane. Obviously i can optimize a lot in the geometry buffer method, like rendering only visible faces of a cube or using larger faces covering multiple cubes if the area is flat. But is a vertex buffer of roughly 67mb the max i can work with or can i create multiple?

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• glColor3f Setting colour

  - by Aaron

  This draws a white vertical line from 640 to 768 at x512: glDisable(GL_TEXTURE_2D); glBegin(GL_LINES); glColor3f((double)R/255,(double)G/255,(double)B/255); glVertex3f(SX, -SPosY, 0); // origin of the line glVertex3f(SX, -EPosY, 0); // ending point of the line glEnd(); glEnable(GL_TEXTURE_2D); This works, but after having a problem where it wouldn't draw it white (Or to any colour passed) I discovered that disabling GL_TEXTURE_2D Before drawing the line, and the re-enabling it afterwards for other things, fixed it. I want to know, is this a normal step a programmer might take? Or is it highly inefficient? I don't want to be causing any slow downs due to a mistake =) Thanks

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• Object detection in bitmap JavaScript canvas

  - by fallenAngel

  I want to detect clicks on canvas elements which are drawn using paths. So far I have stored element paths in a JavaScript data structure and then check the coordinates of hits which match the element's coordinates. Rendering each element path and checking the hits would be inefficient when there are a lot of elements. I believe there must be an algorithm for this kind of coordinate search, can anyone help me with this?

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• Impact of variable-length loops on GPU shaders

  - by Will

  Its popular to render procedural content inside the GPU e.g. in the demoscene (drawing a single quad to fill the screen and letting the GPU compute the pixels). Ray marching is popular: This means the GPU is executing some unknown number of loop iterations per pixel (although you can have an upper bound like maxIterations). How does having a variable-length loop affect shader performance? Imagine the simple ray-marching psuedocode: t = 0.f; while(t < maxDist) { p = rayStart + rayDir * t; d = DistanceFunc(p); t += d; if(d < epsilon) { ... emit p return; } } How are the various mainstream GPU families (Nvidia, ATI, PowerVR, Mali, Intel, etc) affected? Vertex shaders, but particularly fragment shaders? How can it be optimised?

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• Mapping dynamic buffers in Direct3D11 in Windows Store apps

  - by Donnie

  I'm trying to make instanced geometry in Direct3D11, and the ID3D11DeviceContext1->Map() call is failing with the very helpful error of "Invalid Parameter" when I'm attempting to update the instance buffer. The buffer is declared as a member variable: Microsoft::WRL::ComPtr<ID3D11Buffer> m_instanceBuffer; Then I create it (which succeeds): D3D11_BUFFER_DESC instanceDesc; ZeroMemory(&instanceDesc, sizeof(D3D11_BUFFER_DESC)); instanceDesc.Usage = D3D11_USAGE_DYNAMIC; instanceDesc.ByteWidth = sizeof(InstanceData) * MAX_INSTANCE_COUNT; instanceDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; instanceDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE; instanceDesc.MiscFlags = 0; instanceDesc.StructureByteStride = 0; DX::ThrowIfFailed(d3dDevice->CreateBuffer(&instanceDesc, NULL, &m_instanceBuffer)); However, when I try to map it: D3D11_MAPPED_SUBRESOURCE inst; DX::ThrowIfFailed(d3dContext->Map(m_instanceBuffer.Get(), 0, D3D11_MAP_WRITE, 0, &inst)); The map call fails with E_INVALIDARG. Nothing is NULL incorrectly, and this being one of my first D3D apps I'm currently stumped on what to do next to track it down. I'm thinking I must be creating the buffer incorrectly, but I can't see how. Any input would be appreciated.

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• Unexpected results for projection on to plane

  - by ravenspoint

  I want to use this projection matrix: GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; It should cast object shadows onto the y = 0 plane from a point light at 1,1,-1. I create a rectangle in the x = 0.5 plane glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); Now if I manually multiply these vertices with the matrix, I get. glBegin( GL_QUADS ); glVertex3f( 0.375,0,-0.375); glVertex3f( 0.375,0,-1.625); glVertex3f( 0,0,-2); glVertex3f( 0,0,0); glEnd(); Which produces a reasonable display ( camera at 0,5,0 looking down y axis ) So rather than do the calculation manually, I should be able to use the opengl model transormation. I write this code: glMatrixMode (GL_MODELVIEW); GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; glLoadMatrixf( shadow ); glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); But this produces a blank screen! What am I doing wrong? Is there some debug mode where I can print out the transformed vertices, so I can see where they are ending up? Note: People have suggested that using glMultMatrixf() might make a difference. It doesn't. Replacing glLoadMatrixf( shadow ); with glLoadIdentity(); glMultMatrixf( shadow ); gives the identical result ( of course! )

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• why is this rails association loading individually after an eager load?

  - by codeman73

  I'm trying to avoid the N+1 queries problem with eager loading, but it's not working. The associated models are still being loaded individually. Here are the relevant ActiveRecords and their relationships: class Player < ActiveRecord::Base has_one :tableau end Class Tableau < ActiveRecord::Base belongs_to :player has_many :tableau_cards has_many :deck_cards, :through => :tableau_cards end Class TableauCard < ActiveRecord::Base belongs_to :tableau belongs_to :deck_card, :include => :card end class DeckCard < ActiveRecord::Base belongs_to :card has_many :tableaus, :through => :tableau_cards end class Card < ActiveRecord::Base has_many :deck_cards end and the query I'm using is inside this method of Player: def tableau_contains(card_id) self.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', self.tableau.id] contains = false for tableau_card in self.tableau.tableau_cards # my logic here, looking at attributes of the Card model, with # tableau_card.deck_card.card; # individual loads of related Card models related to tableau_card are done here end return contains end Does it have to do with scope? This tableau_contains method is down a few method calls in a larger loop, where I originally tried doing the eager loading because there are several places where these same objects are looped through and examined. Then I eventually tried the code as it is above, with the load just before the loop, and I'm still seeing the individual SELECT queries for Card inside the tableau_cards loop in the log. I can see the eager-loading query with the IN clause just before the tableau_cards loop as well. EDIT: additional info below with the larger, outer loop Here's the larger loop. It is inside an observer on after_save def after_save(pa) @game = Game.find(turn.game_id, :include => :goals) @game.players = Player.find :all, :include => [ {:tableau => (:tableau_cards)}, :player_goals ], :conditions => ['players.game_id =?', @game.id] for player in @game.players player.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', player.tableau.id] if(player.tableau_contains(card)) ... end end end

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• 3D Model not translating correctly (visually)

  - by ChocoMan

  In my first image, my model displays correctly: But when I move the model's position along the Z-axis (forward) I get this, yet the Y-axis doesnt change. An if I keep going, the model disappears into the ground: Any suggestions as to how I can get the model to translate properly visually? Here is how Im calling the model and the terrain in draw(): cameraPosition = new Vector3(camX, camY, camZ); // Copy any parent transforms. Matrix[] transforms = new Matrix[mShockwave.Bones.Count]; mShockwave.CopyAbsoluteBoneTransformsTo(transforms); Matrix[] ttransforms = new Matrix[terrain.Bones.Count]; terrain.CopyAbsoluteBoneTransformsTo(ttransforms); // Draw the model. A model can have multiple meshes, so loop. foreach (ModelMesh mesh in mShockwave.Meshes) { // This is where the mesh orientation is set, as well // as our camera and projection. foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(modelRotation) * Matrix.CreateTranslation(modelPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, modelPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); mesh.Draw(); } //Terrain test foreach (ModelMesh meshT in terrain.Meshes) { foreach (BasicEffect effect in meshT.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = ttransforms[meshT.ParentBone.Index] * Matrix.CreateRotationY(0) * Matrix.CreateTranslation(terrainPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, terrainPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); meshT.Draw(); DrawText(); } base.Draw(gameTime); } Im suspecting that there may be something wrong with how I'm handling my camera. The model rotates fine on its Y-axis.

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• Models with more than one mesh in JMonkeyEngine

  - by Andrea Tucci

  I’m a new jmonkey engine developer and I’m beginning to import models. I tried to import simple models and no problems appeared, but when I export some obj models having more than one mesh in the OgreXML format, Blender saves multiple meshes with their own materials (e.g. one mesh for face, another for body etc). Can I export all the meshes in one? I’ve tried to join all the meshes to a major one with blender (face joins body), but when I export the model and then create the Spatial in jme(loading the path of the “merged” mesh), all the meshes that are joined to the major doesn’t have their materials! I give a more clear example: I have an .obj model with 3 meshes and I export it. I have : mesh1.mesh.xml , mesh2.mesh.xml , mesh3.mesh.xml and their materials mesh1.material, mesh2.material mesh3.material so I import the folder in Assets/Models/Test and now I have to create something like: Spatial head = assetManager.loadModel( [path] ); Spatial face = assetManager.loadModel( [path] ) one for each mesh and than attach them to a common node. I think there is a way to merge those mesh maintaining their materials! What do you think? Thanks

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• Slick2d Spritesheet showing whole image

  - by BotskoNet

  I'm trying to show a single subimage from a sprite sheet. Using slick2d SpriteSheet class, all it's doing is showing me the entire image, but scaled down to fit the cell dimensions. The image is 96x192 and should have cells of 32x32. The code: SpriteSheet spriteSheet = new SpriteSheet("images/"+file, 32, 32 ); System.out.println("Horiz Count: " + spriteSheet.getHorizontalCount()); System.out.println("Vert Count: " + spriteSheet.getVerticalCount()); System.out.println("Height: " + spriteSheet.getHeight()); System.out.println("Width: " + spriteSheet.getWidth()); System.out.println("Texture Width: " + spriteSheet.getTextureWidth()); System.out.println("Texture Height: " + spriteSheet.getTextureHeight()); Prints: Horiz Count: 3 Vert Count: 6 Height: 192 Width: 96 Texture Width: 0.75 Texture Height: 0.75 Not sure what the texture dimensions refer to, but the rest is entirely accurate. However, when I draw the icon, the entire sprite image shows scaled down to 32x32: Image image = spriteSheet.getSprite(1, 0); // a test image.bind(); GL11.glEnable(GL11.GL_BLEND); GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA); GL11.glBegin(GL11.GL_QUADS); GL11.glTexCoord2f(0,0); GL11.glVertex2f(x,y); GL11.glTexCoord2f(1,0); GL11.glVertex2f(x+image.getWidth(),y); GL11.glTexCoord2f(1,1); GL11.glVertex2f(x+image.getWidth(),y+image.getHeight()); GL11.glTexCoord2f(0,1); GL11.glVertex2f(x,y+image.getHeight()); GL11.glEnd(); GL11.glDisable(GL11.GL_BLEND);

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• Mandelbrot set not displaying properly

  - by brainydexter

  I am trying to render mandelbrot set using glsl. I'm not sure why its not rendering the correct shape. Does the mandelbrot calculation require values to be within a range for the (x,y) [ or (real, imag) ] ? Here is a screenshot: I render a quad as follows: float w2 = 6; float h2 = 5; glBegin(GL_QUADS); glVertex3f(-w2, h2, 0.0); glVertex3f(-w2, -h2, 0.0); glVertex3f(w2, -h2, 0.0); glVertex3f(w2, h2, 0.0); glEnd(); My vertex shader: varying vec3 Position; void main(void) { Position = gl_Vertex.xyz; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } My fragment shader (where all the meat is): uniform float MAXITERATIONS; varying vec3 Position; void main (void) { float zoom = 1.0; float centerX = 0.0; float centerY = 0.0; float real = Position.x * zoom + centerX; float imag = Position.y * zoom + centerY; float r2 = 0.0; float iter; for(iter = 0.0; iter < MAXITERATIONS && r2 < 4.0; ++iter) { float tempreal = real; real = (tempreal * tempreal) + (imag * imag); imag = 2.0 * real * imag; r2 = (real * real) + (imag * imag); } vec3 color; if(r2 < 4.0) color = vec3(1.0); else color = vec3( iter / MAXITERATIONS ); gl_FragColor = vec4(color, 1.0); }

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• Moving a body in a specific direction using XNA with Farseer Physics

  - by Code Assasssin

  I have a custom polygon attached to a body, which looks like this: What I am trying to accomplish is getting the body to move according to wherever the tip of the body is. So far this is what I've tried: if (ks.IsKeyDown(Keys.Up)) { body.ApplyForce(new Vector2(0, -20),body.GetLocalPoint(new Vector2(0,0))); } if (ks.IsKeyDown(Keys.Left)) { body.ApplyTorque(-500); } if (ks.IsKeyDown(Keys.Right)) { body.ApplyTorque(500); } The body rotates fine - but when I try making the body accelerate according to the tip of the body - assuming I have specified the tip correctly(I am pretty sure I haven't), it just spins around, as if I have applied Torque to it. Can anyone point me in the right direction of how to fix this problem?

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• Direct2D Transform

  - by James

  I have a beginner question about Direct2D transforms. I have a 20 x 10 bitmap that I would like to draw in different orientations. To start, I would like to draw it vertically with a destination rectangle of say: (left, top, right, bottom) (300, 300, 310, 320) The bitmap is wider than it is tall (20 x 10), but when I draw it vertically, it will be appear taller than it is wide (10 x 20). I know that I can use a rotation matrix like so: m_pRenderTarget->SetTransform( D2D1::Matrix3x2F::Rotation( 90.0f, D2D1::Point2F(<center of shape>)) ); But when I use this method to rotate my shape, the destination rectangle is still wider than it is tall. Maybe it would look something like this: (left, top, right, bottom) (280, 290, 300, 300) The destination rectangle is 20 x 10 but the bitmap appears on the screen as 10 x 20. I can't look at the destination rectangle in the debugger and compare it to: (left, top, right, bottom) (300, 300, 310, 320) Is there any simple way to say "I want to rotate it so that the image is rendered to exactly this destination rectangle after the rotation?" In this case, I would like to say "Please rotate the bitmap so that it appears on the screen at this location:" (left, top, right, bottom) (300, 300, 310, 320) If I can't do that, is there any way to find out the 10 x 20 destination rectangle where the bitmap is actually being rendered to the screen?

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• Foreach loop with 2d array of objects

  - by Jacob Millward

  I'm using a 2D array of objects to store data about tiles, or "blocks" in my gameworld. I initialise the array, fill it with data and then attempt to invoke the draw method of each object. foreach (Block block in blockList) { block.Draw(spriteBatch); } I end up with an exception being thrown "Object reference is not set to an instance of an object". What have I done wrong? EDIT: This is the code used to define the array Block[,] blockList; Then blockList = new Block[screenRectangle.Width, screenRectangle.Height]; // Fill with dummy data for (int x = 0; x <= screenRectangle.Width / texture.Width; x++) { for (int y = 0; y <= screenRectangle.Height / texture.Width; y++) { if (y >= screenRectangle.Height / (texture.Width*2)) { blockList[x, y] = new Block(1, new Rectangle(x * 16, y * 16, texture.Width, texture.Height), texture); } else { blockList[x, y] = new Block(0, new Rectangle(x * 16, y * 16, texture.Width, texture.Height), texture); } } }

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• Arbitrary projection matrix from 6 arbitrary frustum planes

  - by Doub

  A projection matrix represent a tranformation from the camera view space to the rendering system clip space. In other words, it defines the transormation between a 6-sided frustum to the clip cube. The glOrtho and glFrustum use only 6 parameter to define such a projection, but impose several constraints on the frustum that will get projected to the clip cube: the near and far planes are parallel, the left and right planes intersect on a vertical line, and the top and bottom planes intersect on a horizontal lines, both lines being parallel to the near and far planes. I'd like to lift these restrictions. So, from the definition of the 6 frustum side planes (in whatever representation you see fit), how can I compute a general projection matrix?

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• Lwjgl or opengl double pixels

  - by Philippe Paré

  I'm working in java with LWJGL and trying to double all my pixels. I'm trying to draw in an area of 800x450 and then stretch all the frame image to the complete 1600x900 pixels without them getting blured. I can't figure out how to do that in java, everything I find is in c++... A hint would be great! Thanks a lot. EDIT : I've tried drawing to a texture created in opengl by setting it to the framebuffer, but I can't find a way to use glGenTextures() in java... so this is not working... also I though about using a shader but I would not be able to draw only in the smaller region...

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• Collision detection code style

  - by Marian Ivanov

  Not only there are two useful broad-phase algorithms and a lot of useful narrowphase algorithms, there are also multiple code styles. Arrays vs. calling Make an array of broadphase checks, then filter them with narrowphase checks, then resolve them. function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ possibleCollisions = getPossibleCollisions(b,a->get(index)); for(i=0; i<possibleCollitionsNumber; i++){ if(narrowphase(possibleCollisions[i],a[index])) { collisions->push(possibleCollisions[i]); }; }; for(i=0; i<collitionsNumber; i++){ //CODE FOR RESOLUTION }; }; Make the broadphase call the narrowphase, and the narrowphase call the resolution function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ broadphase(b,a->get(index)); }; function broadphase(thingy * with, thingy * what){ while(blah){ //blahcode narrowphase(what,collidingThing); }; }; Events vs. in-the-loop Fire an event. This abstracts the check away, but it's trickier to make an equal interaction. a[index] -> collisionEvent(eventdata); //much later int collisionEvent(eventdata){ //resolution gets here } Resolve the collision inside the loop. This glues narrowphase and resolution into one layer. if(narrowphase(possibleCollisions[i],a[index])) { //CODE GOES HERE }; The questions are: Which of the first two is better, and how am I supposed to make a zero-sum Newtonian interaction under B1.

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• Scrolling a WriteableBitmap

  - by Skoder

  I need to simulate my background scrolling but I want to avoid moving my actual image control. Instead, I'd like to use a WriteableBitmap and use a blitting method. What would be the way to simulate an image scrolling upwards? I've tried various things buy I can't seem to get my head around the logic: //X pos, Y pos, width, height Rect src = new Rect(0, scrollSpeed , 480, height); Rect dest = new Rect(0, 700 - scrollSpeed , 480, height); //destination rect, source WriteableBitmap, source Rect, blend mode wb.Blit(destRect, wbSource, srcRect, BlendMode.None); scrollSpeed += 5; if (scrollSpeed > 700) scrollSpeed = 0; If height is 10, the image is quite fuzzy and moreso if the height is 1. If the height is a taller, the image is clearer, but it only seems to do a one to one copy. How can I 'scroll' the image so that it looks like it's moving up in a continuous loop? (The height of the screen is 700).

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• How can I transform a Point2f with a matrix on Android?

  - by Vivendi

  I'm developing for Android and I'm using the android.renderscript.Matrix3f class to do some calculations. What I need to do now is to now is to do something like mat.tranform(pointIn, pointOut); So I need to transform a matrix by a given Point class. In awt I would simply do this: AffineTransform t = new AffineTransform(); Point2D.Float p = new Point2D.Float(); t.transform( p, p ); But in Android I now have this: Matrix3f t = new Matrix3f(); PointF p = new PointF(); // Now I need to tranform it somehow.. But the Matrix3f class in Android doesn't have a Matrix.transform(Point2D ptSrc, Point2D ptDst) method. So I guess I have to do the transformation manually. But I'm not really sure how that works. From what I've seen it's something like a translate and then a rotate? Could anyone please tell me how to do this in code?

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