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• How to snap a 2D Quad to the mouse cursor using OpenGL 3.0?

  - by NoobScratcher

  I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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• Color Picking Troubles - LWJGL/OpenGL

  - by Tom Johnson

  I'm attempting to check which object the user is hovering over. While everything seems to be just how I'd think it should be, I'm not able to get the correct color due to the second time I draw (without picking colors). Here is my rendering code: public void render() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); camera.applyTranslations(); scene.pick(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); camera.applyTranslations(); scene.render(); } And here is what gets called on each block/tile on "scene.pick()": public void pick() { glColor3ub((byte) pickingColor.x, (byte) pickingColor.y, (byte) pickingColor.z); draw(); glReadBuffer(GL_FRONT); ByteBuffer buffer = BufferUtils.createByteBuffer(4); glReadPixels(Mouse.getX(), Mouse.getY(), 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, buffer); int r = buffer.get(0) & 0xFF; int g = buffer.get(1) & 0xFF; int b = buffer.get(2) & 0xFF; if(r == pickingColor.x && g == pickingColor.y && b == pickingColor.z) { hovered = true; } else { hovered = false; } } I believe the problem is that in the method of each tile/block called by scene.pick(), it is reading the color from the regular drawing state, after that method is called somehow. I believe this because when I remove the "glReadBuffer(GL_FRONT)" line from the pick method, it seems to almost fix it, but then it will also select blocks behind the one you are hovering as it is not only looking at the front. If you have any ideas of what to do, please be sure to reply!/ EDIT: Adding scene.render(), tile.render(), and tile.draw() scene.render: public void render() { for(int x = 0; x < tiles.length; x++) { for(int z = 0; z < tiles.length; z++) { tiles[x][z].render(); } } } tile.render: public void render() { glColor3f(color.x, color.y, color.z); draw(); if(hovered) { glColor3f(1, 1, 1); glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); draw(); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); } } tile.draw: public void draw() { float x = position.x, y = position.y, z = position.z; //Top glBegin(GL_QUADS); glVertex3f(x, y + size, z); glVertex3f(x + size, y + size, z); glVertex3f(x + size, y + size, z + size); glVertex3f(x, y + size, z + size); glEnd(); //Left glBegin(GL_QUADS); glVertex3f(x, y, z); glVertex3f(x + size, y, z); glVertex3f(x + size, y + size, z); glVertex3f(x, y + size, z); glEnd(); //Right glBegin(GL_QUADS); glVertex3f(x + size, y, z); glVertex3f(x + size, y + size, z); glVertex3f(x + size, y + size, z + size); glVertex3f(x + size, y, z + size); glEnd(); } (The game is like an isometric game. That's why I only draw 3 faces.)

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• converting 2D mouse coordinates to 3D space in OpenGL ES

  - by Jayesh

  I want to convert mouse's current X and Y coordinates into the 3D space I have drawn in the viewport. I need to do this on the OpenGL ES platform. I found following possible solutions implemented in OpenGL, but none fits what I am looking for. I found NeHe's tutorial on doing exactly this, but in traditional OpenGL way. It uses gluUnProject. http://nehe.gamedev.net/data/articles/article.asp?article=13 Although gluUnProject is not available in OpenGL ES, its implementation seems simple enough to port back. But before calling it, we need to call glReadPixels with GL_DEPTH_COMPONENT and that is not possible in OpenGL ES. (The reason I found in this thread: http://www.khronos.org/message_boards/viewtopic.php?f=4&t=771) What I want to do is similar to picking, except that I don't want to select the object but I want exact coordinates so that I can recognize particular portion of the object that is currently under mouse cursor. I went through the Picking tutorials in this answer. http://stackoverflow.com/posts/2211312/revisions But they need glRenderMode, which I believe is absent in OpenGL ES. If you know how to solve this problem in OpenGL ES, please let me know. Thanks.

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• Fast screen capture and lost Vsync

  - by user338759

  Hi, I'd like to generate a movie in real time with a self-made application doing fast screen captures with part of the screen occupied by a running 3D application. I'm aware that several applications already exist for this (like FRAPS or Taksi), and even dedicated DirectShow filters (like UScreenCapture), but i really need to make this with my own external application. When correctly setup (UScreenCapture + ffdshow), capturing an compressing a full screen does not consumes as much CPU as you would expect (about 15%), and does not impairs the performances of the 3D app. The problem of doing a capture from an external application is that the 3D application loses it's Vsync and creates a shaggy, difficult to use 3D application (3D app is only presented on a small part of the screen, the rest being GDI, DirectX) FRAPS solves this problem by allowing you to capture only one application at a time (the one with focus). Depending on the technology used (OpenGl, DirectX, GDI), it hooks the Vsync and does its capture (with glReadPixels,...), without perturbing it. Doing this does not solve my problem, since I want the full composed screen image (including 3D and the rest) AND a smooth 3D app. The UScreenCapture seems to use a fast DirectX call to capture the whole screen, but the openGL 3D app is still out of sync. Doing a BitBlt is too slow and CPU consumming to do real time 30 fps acquisition (at least under windows XP, not sure with 7) My question is to know if there is a way to achieve my goal with Windows 7 and it's brand new DirectX compositing engine? Windows 7 succeeds to show live VSynced duplicated previews of every app (in the taskbar), so there must be a way to access the currenlty displayed screen buffer without perturbing the rendering of the 3D OpenGL app ? Any other suggestion, technology ? thank you

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• flood fill algorithm

  - by user335593

  i want to implement the flood fill algorthm...so that when i get the x and y co-od of a point...it should start flooding from that point and fill till it finds a boundary but it is not filling the entire region...say a pentagon this is the code i am using void setpixel(struct fill fillcolor,int x,int y) { glColor3f(fillcolor.r,fillcolor.g,fillcolor.b); glBegin(GL_POINTS); glVertex2i(x,y); glEnd(); glFlush(); } struct fill getpixcol(int x,int y) { struct fill gotpixel; glReadPixels(x,y,1,1,GL_RGB,GL_UNSIGNED_BYTE,pick_col); gotpixel.r =(float) pick_col[0]/255.0; gotpixel.g =(float) pick_col[1]/255.0; gotpixel.b =(float) pick_col[2]/255.0; return(gotpixel); } void floodFill(int x, int y,struct fill fillcolor,struct fill boundarycolor) { struct fill tmp; // if ((x < 0) || (x >= 500)) return; // if ((y < 0) || (y >= 500)) return; tmp=getpixcol(x,y); while (tmp.r!=boundarycolor.r && tmp.g!=boundarycolor.g && tmp.b!=boundarycolor.b) { setpixel(fillcolor,x,y); setpixel(fillcolor,x+1,y); setpixel(fillcolor,x,y+1); setpixel(fillcolor,x,y-1); setpixel(fillcolor,x-1,y); floodFill(x-1,y+1,fillcolor,boundarycolor); floodFill(x-1,y,fillcolor,boundarycolor); floodFill(x-1,y-1,fillcolor,boundarycolor); floodFill(x,y+1,fillcolor,boundarycolor); floodFill(x,y-1,fillcolor,boundarycolor); floodFill(x+1,y+1,fillcolor,boundarycolor); floodFill(x+1,y,fillcolor,boundarycolor); floodFill(x+1,y-1,fillcolor,boundarycolor); } }

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• displaying a saved buffer in OpenGL ES

  - by Adam

  Hi everyone, So basically I have a screenshot that I've saved that I want to later display on the screen. I've saved it with: glReadPixels(0, 0, self.bounds.size.width, self.bounds.size.height, GL_RGBA, GL_UNSIGNED_BYTE, savedBuffer); And later I'm trying to write it to the screen with: GLuint RenderedTex; glGenTextures(1, &RenderedTex); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, RenderedTex); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA, self.bounds.size.width, self.bounds.size.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, savedBuffer); glDisable(GL_TEXTURE_2D); I'm pretty new to OpenGL so I don't know if I'm doing things right... actually I know I'm not, because nothing shows up. Also not sure how to dispose of the texture when I'm done with it. Anyone know the correct way to do this? Edit: I think I might be having a problem loading the texture because it's not a power of 2, it's 320x480... also, I think this code is just loading the texture, but not drawing it, I'd need a call to glDrawArrays(GL_TRIANGLE_STRIP, 0, 4) in there somewhere...

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• Basic shadow mapping fails on NVIDIA card?

  - by James

  Recently I switched from an AMD Radeon HD 6870 card to an (MSI) NVIDIA GTX 670 for performance reasons. I found however that my implementation of shadow mapping in all my applications failed. In a very simple shadow POC project the problem appears to be that the scene being drawn never results in a draw to the depth map and as a result the entire depth map is just infinity, 1.0 (Reading directly from the depth component after draw (glReadPixels) shows every pixel is infinity (1.0), replacing the depth comparison in the shader with a comparison of the depth from the shadow map with 1.0 shadows the entire scene, and writing random values to the depth map and then not calling glClear(GL_DEPTH_BUFFER_BIT) results in a random noisy pattern on the scene elements - from which we can infer that the uploading of the depth texture and comparison within the shader are functioning perfectly.) Since the problem appears almost certainly to be in the depth render, this is the code for that: const int s_res = 1024; GLuint shadowMap_tex; GLuint shadowMap_prog; GLint sm_attr_coord3d; GLint sm_uniform_mvp; GLuint fbo_handle; GLuint renderBuffer; bool isMappingShad = false; //The scene consists of a plane with box above it GLfloat scene[] = { -10.0, 0.0, -10.0, 0.5, 0.0, 10.0, 0.0, -10.0, 1.0, 0.0, 10.0, 0.0, 10.0, 1.0, 0.5, -10.0, 0.0, -10.0, 0.5, 0.0, -10.0, 0.0, 10.0, 0.5, 0.5, 10.0, 0.0, 10.0, 1.0, 0.5, ... }; //Initialize the stuff used by the shadow map generator int initShadowMap() { //Initialize the shadowMap shader program if (create_program("shadow.v.glsl", "shadow.f.glsl", shadowMap_prog) != 1) return -1; const char* attribute_name = "coord3d"; sm_attr_coord3d = glGetAttribLocation(shadowMap_prog, attribute_name); if (sm_attr_coord3d == -1) { fprintf(stderr, "Could not bind attribute %s\n", attribute_name); return 0; } const char* uniform_name = "mvp"; sm_uniform_mvp = glGetUniformLocation(shadowMap_prog, uniform_name); if (sm_uniform_mvp == -1) { fprintf(stderr, "Could not bind uniform %s\n", uniform_name); return 0; } //Create a framebuffer glGenFramebuffers(1, &fbo_handle); glBindFramebuffer(GL_FRAMEBUFFER, fbo_handle); //Create render buffer glGenRenderbuffers(1, &renderBuffer); glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer); //Setup the shadow texture glGenTextures(1, &shadowMap_tex); glBindTexture(GL_TEXTURE_2D, shadowMap_tex); glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, s_res, s_res, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); return 0; } //Delete stuff void dnitShadowMap() { //Delete everything glDeleteFramebuffers(1, &fbo_handle); glDeleteRenderbuffers(1, &renderBuffer); glDeleteTextures(1, &shadowMap_tex); glDeleteProgram(shadowMap_prog); } int loadSMap() { //Bind MVP stuff glm::mat4 view = glm::lookAt(glm::vec3(10.0, 10.0, 5.0), glm::vec3(0.0, 0.0, 0.0), glm::vec3(0.0, 1.0, 0.0)); glm::mat4 projection = glm::ortho<float>(-10,10,-8,8,-10,40); glm::mat4 mvp = projection * view; glm::mat4 biasMatrix( 0.5, 0.0, 0.0, 0.0, 0.0, 0.5, 0.0, 0.0, 0.0, 0.0, 0.5, 0.0, 0.5, 0.5, 0.5, 1.0 ); glm::mat4 lsMVP = biasMatrix * mvp; //Upload light source matrix to the main shader programs glUniformMatrix4fv(uniform_ls_mvp, 1, GL_FALSE, glm::value_ptr(lsMVP)); glUseProgram(shadowMap_prog); glUniformMatrix4fv(sm_uniform_mvp, 1, GL_FALSE, glm::value_ptr(mvp)); //Draw to the framebuffer (with depth buffer only draw) glBindFramebuffer(GL_FRAMEBUFFER, fbo_handle); glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer); glBindTexture(GL_TEXTURE_2D, shadowMap_tex); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, shadowMap_tex, 0); glDrawBuffer(GL_NONE); glReadBuffer(GL_NONE); GLenum result = glCheckFramebufferStatus(GL_FRAMEBUFFER); if (GL_FRAMEBUFFER_COMPLETE != result) { printf("ERROR: Framebuffer is not complete.\n"); return -1; } //Draw shadow scene printf("Creating shadow buffers..\n"); int ticks = SDL_GetTicks(); glClear(GL_DEPTH_BUFFER_BIT); //Wipe the depth buffer glViewport(0, 0, s_res, s_res); isMappingShad = true; //DRAW glEnableVertexAttribArray(sm_attr_coord3d); glVertexAttribPointer(sm_attr_coord3d, 3, GL_FLOAT, GL_FALSE, 5*4, scene); glDrawArrays(GL_TRIANGLES, 0, 14*3); glDisableVertexAttribArray(sm_attr_coord3d); isMappingShad = false; glBindFramebuffer(GL_FRAMEBUFFER, 0); printf("Render Sbuf in %dms (GLerr: %d)\n", SDL_GetTicks() - ticks, glGetError()); return 0; } This is the full code for the POC shadow mapping project (C++) (Requires SDL 1.2, SDL-image 1.2, GLEW (1.5) and GLM development headers.) initShadowMap is called, followed by loadSMap, the scene is drawn from the camera POV and then dnitShadowMap is called. I followed this tutorial originally (Along with another more comprehensive tutorial which has disappeared as this guy re-configured his site but used to be here (404).) I've ensured that the scene is visible (as can be seen within the full project) to the light source (which uses an orthogonal projection matrix.) Shader utilities function fine in non-shadow-mapped projects. I should also note that at no point is the GL error state set. What am I doing wrong here and why did this not cause problems on my AMD card? (System: Ubuntu 12.04, Linux 3.2.0-49-generic, 64 bit, with the nvidia-experimental-310 driver package. All other games are functioning fine so it's most likely not a card/driver issue.)

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• Unexpected behaviour with glFramebufferTexture1D

  - by Roshan

  I am using render to texture concept with glFramebufferTexture1D. I am drawing a cube on non-default FBO with all the vertices as -1,1 (maximum) in X Y Z direction. Now i am setting viewport to X while rendering on non default FBO. My background is blue with white color of cube. For default FBO, i have created 1-D texture and attached this texture to above FBO with color attachment. I am setting width of texture equal to width*height of above FBO view-port. Now, when i render this texture to on another cube, i can see continuous white color on start or end of each face of the cube. That means part of the face is white and rest is blue. I am not sure whether this behavior is correct or not. I expect all the texels should be white as i am using -1 and 1 coordinates for cube rendered on non-default FBO. code: #define WIDTH 3 #define HEIGHT 3 GLfloat vertices8[]={ 1.0f,1.0f,1.0f, -1.0f,1.0f,1.0f, -1.0f,-1.0f,1.0f, 1.0f,-1.0f,1.0f,//face 1 1.0f,-1.0f,-1.0f, -1.0f,-1.0f,-1.0f, -1.0f,1.0f,-1.0f, 1.0f,1.0f,-1.0f,//face 2 1.0f,1.0f,1.0f, 1.0f,-1.0f,1.0f, 1.0f,-1.0f,-1.0f, 1.0f,1.0f,-1.0f,//face 3 -1.0f,1.0f,1.0f, -1.0f,1.0f,-1.0f, -1.0f,-1.0f,-1.0f, -1.0f,-1.0f,1.0f,//face 4 1.0f,1.0f,1.0f, 1.0f,1.0f,-1.0f, -1.0f,1.0f,-1.0f, -1.0f,1.0f,1.0f,//face 5 -1.0f,-1.0f,1.0f, -1.0f,-1.0f,-1.0f, 1.0f,-1.0f,-1.0f, 1.0f,-1.0f,1.0f//face 6 }; GLfloat vertices[]= { 0.5f,0.5f,0.5f, -0.5f,0.5f,0.5f, -0.5f,-0.5f,0.5f, 0.5f,-0.5f,0.5f,//face 1 0.5f,-0.5f,-0.5f, -0.5f,-0.5f,-0.5f, -0.5f,0.5f,-0.5f, 0.5f,0.5f,-0.5f,//face 2 0.5f,0.5f,0.5f, 0.5f,-0.5f,0.5f, 0.5f,-0.5f,-0.5f, 0.5f,0.5f,-0.5f,//face 3 -0.5f,0.5f,0.5f, -0.5f,0.5f,-0.5f, -0.5f,-0.5f,-0.5f, -0.5f,-0.5f,0.5f,//face 4 0.5f,0.5f,0.5f, 0.5f,0.5f,-0.5f, -0.5f,0.5f,-0.5f, -0.5f,0.5f,0.5f,//face 5 -0.5f,-0.5f,0.5f, -0.5f,-0.5f,-0.5f, 0.5f,-0.5f,-0.5f, 0.5f,-0.5f,0.5f//face 6 }; GLuint indices[] = { 0, 2, 1, 0, 3, 2, 4, 5, 6, 4, 6, 7, 8, 9, 10, 8, 10, 11, 12, 15, 14, 12, 14, 13, 16, 17, 18, 16, 18, 19, 20, 23, 22, 20, 22, 21 }; GLfloat texcoord[] = { 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0 }; glGenTextures(1, &id1); glBindTexture(GL_TEXTURE_1D, id1); glGenFramebuffers(1, &Fboid); glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexImage1D(GL_TEXTURE_1D, 0, GL_RGBA, WIDTH*HEIGHT , 0, GL_RGBA, GL_UNSIGNED_BYTE,0); glBindFramebuffer(GL_FRAMEBUFFER, Fboid); glFramebufferTexture1D(GL_DRAW_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,GL_TEXTURE_1D,id1,0); draw_cube(); glBindFramebuffer(GL_FRAMEBUFFER, 0); draw(); } draw_cube() { glViewport(0, 0, WIDTH, HEIGHT); glClearColor(0.0f, 0.0f, 0.5f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); glEnableVertexAttribArray(glGetAttribLocation(temp.psId,"position")); glVertexAttribPointer(glGetAttribLocation(temp.psId,"position"), 3, GL_FLOAT, GL_FALSE, 0,vertices8); glDrawArrays (GL_TRIANGLE_FAN, 0, 24); } draw() { glClearColor(1.0f, 0.0f, 0.0f, 1.0f); glClearDepth(1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnableVertexAttribArray(glGetAttribLocation(shader_data.psId,"tk_position")); glVertexAttribPointer(glGetAttribLocation(shader_data.psId,"tk_position"), 3, GL_FLOAT, GL_FALSE, 0,vertices); nResult = GL_ERROR_CHECK((GL_NO_ERROR, "glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, 0,vertices);")); glEnableVertexAttribArray(glGetAttribLocation(shader_data.psId,"inputtexcoord")); glVertexAttribPointer(glGetAttribLocation(shader_data.psId,"inputtexcoord"), 2, GL_FLOAT, GL_FALSE, 0,texcoord); glBindTexture(*target11, id1); glDrawElements ( GL_TRIANGLES, 36,GL_UNSIGNED_INT, indices ); when i change WIDTH=HEIGHT=2, and call a glreadpixels with height, width equal to 4 in draw_cube() i can see first 2 pixels with white color, next two with blue(glclearcolor), next two white and then blue and so on.. Now when i change width parameter in glTeximage1D to 16 then ideally i should see alternate patches of white and blue right? But its not the case here. why so?

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• Trying to convert openGL to MFC coordinates and having Problems with "gluProject"

  - by Erez

  Hi, i'm trying to find the naswer on the web and can't find a full solution that i can use and that will work... I'm developing a MFC project with static picture as the canvas for an openGL class that draw the grphics for my game. On moush down, i need to retrive a shape coordinate from the openGL class. I'm looking for a way to convert the openGL coordinates to MFC coordinates but no matter what i try i get junk after using the gluProject or gluUnProject (i've tried to do both ways but non is working) GLdouble modelMatrix[16]; glGetDoublev(GL_MODELVIEW_MATRIX,modelMatrix); GLdouble projMatrix[16]; glGetDoublev(GL_PROJECTION_MATRIX,projMatrix); int viewport[4]; glGetIntegerv(GL_VIEWPORT,viewport); POINT mouse; // Stores The X And Y Coords For The Current Mouse Position GetCursorPos(&mouse); // Gets The Current Cursor Coordinates (Mouse Coordinates) ScreenToClient(hWnd, &mouse); GLdouble winX, winY, winZ; // Holds Our X, Y and Z Coordinates winX; = (float)point.x; // Holds The Mouse X Coordinate winY; = (float)point.y; // Holds The Mouse Y Coordinate winY = (float)viewport[3] - winY; glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); GLdouble posX=s1->getPosX(), posY=s1->getPosY(), posZ=s1->getPosZ(); // Hold The Final Values gluUnProject( winX, winY, winZ, modelMatrix, projMatrix, viewport, &posX, &posY, &posZ); gluProject(posX, posY, posZ, modelMatrix, projMatrix, viewport, &winX, &winY, &winZ); This is just part of the code i've tried. ofcourse not gluProject and gluUnProject together. just had them both here to show.....and i know there is lots of junk over there, its from some of my tries... p.s. i've tried many many more combinations and examples from the web and nothing seem to work in my case.... Can any one show me what is the right way to do the transformation? 10x

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• Missing part of the image when taking screenshot while supporting Retina Display

  - by Spaft

  I'm currently working on enabling support for retina display for my game. In the game, we have a feature that the user can take screenshot. We are using these part of code we found online a while ago and it's working fine when we are not supporting retina display: CCDirector* director = [CCDirector sharedDirector]; CGSize size = [director winSizeInPixels]; //Create buffer for pixels GLuint bufferLength = size.width * size.height * 4; GLubyte* buffer = (GLubyte*)malloc(bufferLength); //Read Pixels from OpenGL glReadPixels(0, 100, size.width, size.height, GL_RGBA, GL_UNSIGNED_BYTE, buffer); //Make data provider with data. CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, bufferLength, NULL); //Configure image int bitsPerComponent = 8; int bitsPerPixel = 32; int bytesPerRow = 4 * size.width; CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault; CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault; CGImageRef iref = CGImageCreate(size.width, size.height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent); uint32_t* pixels = (uint32_t*)malloc(bufferLength); CGContextRef context = CGBitmapContextCreate(pixels, size.width, size.height, 8, size.width * 4, CGImageGetColorSpace(iref), kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGContextTranslateCTM(context, 0, size.height); CGContextScaleCTM(context, 1.0f, -1.0f); switch (director.deviceOrientation) { case CCDeviceOrientationPortrait: break; case CCDeviceOrientationPortraitUpsideDown: CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(180)); CGContextTranslateCTM(context, -size.width, -size.height); break; case CCDeviceOrientationLandscapeLeft: CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(-90)); CGContextTranslateCTM(context, -size.width, 0); break; case CCDeviceOrientationLandscapeRight: CGContextRotateCTM(context, CC_DEGREES_TO_RADIANS(90)); CGContextTranslateCTM(context, size.width * 0.5f, -size.height); break; } CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, size.width, size.height), iref); UIImage *outputImage = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)]; //Dealloc CGDataProviderRelease(provider); CGImageRelease(iref); CGContextRelease(context); free(buffer); free(pixels); return outputImage; But when we enabled retina display in cocos 0.99.5. This functionality is a little messed up since it will miss a little left part of the image while the high is still correct. So I'm wondering if there is anything wrong with the code or am I doing anything wrong here? Thank you in advance for any reply!

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• Problem exporting NSOpenGLView pixel data to some image file formats using ImageKit & CGImageDestina

  - by walkytalky

  I am developing an application to visualise some experimental data. One of its functions is to render the data in an NSOpenGLView subclass, and allow the resulting image to be exported to a file or copied to the clipboard. The view exports the data as an NSImage, generated like this: - (NSImage*) image { NSBitmapImageRep* imageRep; NSImage* image; NSSize viewSize = [self bounds].size; int width = viewSize.width; int height = viewSize.height; [self lockFocus]; [self drawRect:[self bounds]]; [self unlockFocus]; imageRep=[[[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL pixelsWide:width pixelsHigh:height bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:NO colorSpaceName:NSDeviceRGBColorSpace bytesPerRow:width*4 bitsPerPixel:32] autorelease]; [[self openGLContext] makeCurrentContext]; glReadPixels(0,0,width,height,GL_RGBA,GL_UNSIGNED_BYTE,[imageRep bitmapData]); image=[[[NSImage alloc] initWithSize:NSMakeSize(width,height)] autorelease]; [image addRepresentation:imageRep]; [image setFlipped:YES]; // this is deprecated in 10.6 [image lockFocusOnRepresentation:imageRep]; // this will flip the rep [image unlockFocus]; return image; } Copying uses this image very simply, like this: - (IBAction) copy:(id) sender { NSImage* img = [self image]; NSPasteboard* pb = [NSPasteboard generalPasteboard]; [pb clearContents]; NSArray* copied = [NSArray arrayWithObject:img]; [pb writeObjects:copied]; } For file writing, I use the ImageKit IKSaveOptions accessory panel to set the output file type and associated options, then use the following code to do the writing: NSImage* glImage = [glView image]; NSRect rect = [glView bounds]; rect.origin.x = rect.origin.y = 0; img = [glImage CGImageForProposedRect:&rect context:[NSGraphicsContext currentContext] hints:nil]; if (img) { NSURL* url = [NSURL fileURLWithPath: path]; CGImageDestinationRef dest = CGImageDestinationCreateWithURL((CFURLRef)url, (CFStringRef)newUTType, 1, NULL); if (dest) { CGImageDestinationAddImage(dest, img, (CFDictionaryRef)[imgSaveOptions imageProperties]); CGImageDestinationFinalize(dest); CFRelease(dest); } } (I've trimmed a bit of extraneous code here, but nothing that would affect the outcome as far as I can see. The newUTType comes from the IKSaveOptions panel.) This works fine when the file is exported as GIF, JPEG, PNG, PSD or TIFF, but exporting to PDF, BMP, TGA, ICNS and JPEG-2000 produces a red colour artefact on part of the image. Example images are below, the first exported as JPG, the second as PDF. Copy to clipboard does not exhibit this red stripe with the current implementation of image, but it did with the original implementation, which generated the imageRep using NSCalibratedRGBColorSpace rather than NSDeviceRGBColorSpace. So I'm guessing there's some issue with the colour representation in the pixels I get from OpenGL that doesn't get through the subsequent conversions properly, but I'm at a loss as to what to do about it. So, can anyone tell me (i) what is causing this, and (ii) how can I make it go away? I don't care so much about all of the formats but I'd really like at least PDF to work.

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• Boundary fill problem

  - by Taaseen

  hi...Im stuck in this bunch of codes...i cant get the pixel to fill up the circle??...any help #include<iostream> #include<glut.h> struct Color{ float red, green, blue; }; Color getPixel(int x, int y){ // gets the color of the pixel at (x,y) Color c; float color[4]; glReadPixels(x,y,1,1,GL_RGBA, GL_FLOAT, color); c.red = color[0]; c.green = color[1]; c.blue = color[2]; return c; } void setPixel(int x, int y, Color c){ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushAttrib(GL_ALL_ATTRIB_BITS); glColor3f(c.red, c.green, c.blue); glBegin(GL_POINTS); glVertex2i(x,y); glEnd(); glPopAttrib(); glFlush(); } void init() { glClearColor(1.0,1.0,1.0,0.0); gluOrtho2D(0.0,300.0,0.0,300.0); } void drawPixel(int x,int y) { glBegin(GL_POINTS); glVertex2i(x,y); glEnd(); glFlush(); } void Boundary_fill(int x,int y,Color thisColor){ Color boundary_color; boundary_color.red=0.0; boundary_color.green=1.0; boundary_color.blue=0.0; Color nextpixel=getPixel(x,y); if((nextpixel.red!=boundary_color.red)&&(nextpixel.blue!=boundary_color.blue)&&(nextpixel.green!=boundary_color.green) && (nextpixel.red!=thisColor.red)&& (nextpixel.blue!=thisColor.blue)&& (nextpixel.green!=thisColor.green)){ setPixel(x,y,thisColor); Boundary_fill((x+1),y,thisColor); Boundary_fill((x-1),y,thisColor); Boundary_fill(x,(y+1),thisColor); Boundary_fill(x,(y-1),thisColor); } } void draw(int x1,int y1, int x, int y){ drawPixel(x1+x,y1+y);//quadrant1 drawPixel(x1+x,y1-y);//quadrant2 drawPixel(x1-x,y1+y);//quadrant3 drawPixel(x1-x,y1-y);//quadrant4 drawPixel(x1+y,y1+x);//quadrant5 drawPixel(x1+y,y1-x);//quadrant6 drawPixel(x1-y,y1+x);//quadrant7 drawPixel(x1-y,y1-x);//quadrant8 } void circle(int px,int py,int r){ int a,b; float p; a=0; b=r; p=(5/4)-r; while(a<=b){ draw(px,py,a,b); if(p<0){ p=p+(2*a)+1; } else{ b=b-1; p=p+(2*a)+1-(2*b); } a=a+1; } } void Circle(void) { Color thisColor; thisColor.red=1.0; thisColor.blue=0.0; thisColor.green=0.0; glClear(GL_COLOR_BUFFER_BIT); glColor3f(0.0,1.0,0.0); glPointSize(2.0); int x0 = 100; int y0 = 150; circle(x0,y0,50); glColor3f(thisColor.red,thisColor.blue,thisColor.green); Boundary_fill(x0,y0,thisColor); } void main(int argc, char**argv) { glutInit(&argc,argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(400,400); glutInitWindowPosition(1,1); glutCreateWindow("Boundary fill in a circle:Taaseen And Abhinav"); init(); glutDisplayFunc(Circle); glutMainLoop(); }

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• screnshot in android

  - by ujjawal

  The following is the code I am using to take a screen shot using GLSurfaceView. But I dont know why the onDraw() method in the GLSurfaceView.Renderer Class is not being called. Please if some one can look at the code below and point out what am I doing wrong.`public class MainActivity extends Activity { private GLSurfaceView mGLView; int x,y,w,h; Display disp; /** Called when the activity is first created. */ @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); // ToDo add your GUI initialization code here setContentView(R.layout.main); x=0; y=0; disp = getWindowManager().getDefaultDisplay(); w = disp.getWidth(); h = disp.getHeight(); mGLView = new ClearGLSurfaceView(this); } class ClearGLSurfaceView extends GLSurfaceView { public ClearGLSurfaceView(Context context) { super(context); setDebugFlags(DEBUG_CHECK_GL_ERROR | DEBUG_LOG_GL_CALLS); mRenderer = new ClearRenderer(); setRenderer(mRenderer); } ClearRenderer mRenderer; } class ClearRenderer implements GLSurfaceView.Renderer { public void onSurfaceCreated(GL10 gl, EGLConfig config) { // Do nothing special. } public void onSurfaceChanged(GL10 gl, int w, int h) { //gl.glViewport(0, 0, w, h); } public void onDrawFrame(GL10 gl) { //gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); int b[]=new int[w*(y+h)]; int bt[]=new int[w*h]; IntBuffer ib=IntBuffer.wrap(b); ib.position(0); gl.glReadPixels(x, 0, w, y+h, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, ib); for(int i=0, k=0; i<h; i++, k++) {//remember, that OpenGL bitmap is incompatible with Android bitmap //and so, some correction need. for(int j=0; j<w; j++) { int pix=b[i*w+j]; int pb=(pix>>16)&0xff; int pr=(pix<<16)&0x00ff0000; int pix1=(pix&0xff00ff00) | pr | pb; bt[(h-k-1)*w+j]=pix1; } } Bitmap bmp = Bitmap.createBitmap(bt, w, h,Bitmap.Config.ARGB_8888); try { File f = new File("/sdcard/testpicture.png"); f.createNewFile(); FileOutputStream fos=new FileOutputStream(f); bmp.compress(CompressFormat.PNG, 100, fos); try { fos.flush(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { fos.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } } } } ` Please someone help me out. I have just started learning to work on android.

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• OpenGL, draw two polygons in the same time (by mouse clicks)

  - by YoungSalafi

  im trying to draw 2 polygons at the same time depending on user input from the opengl screen... so i made 2 arrays which each one of them will carry the vertices of each polygon ... i think my logic is right but the program still prints only polygon and delete the old polygon if you draw a polygon again . and its acting weird too please check the code yourself here it is : P.S dont mind the delete function right now.. i know it missing something. #include <windows.h> #include <gl/gl.h> #include <gl/glut.h> void Draw(); void Set_Transformations(); void Initialize(int argc, char *argv[]); void OnKeyPress(unsigned char key, int x, int y); void DeleteVer(); void MouseClick(int bin, int state , int x , int y); void GetOGLPos(int x, int y,float* arrY,float* arrX); void DrawPolygon(float* arrX,float* arrY); float xPos[20]; float yPos[20]; float xPos2[20]; float yPos2[20]; float fx = 0,fy = 0; float size = 10; int count = 0; bool done = false; bool flag = true; void Initialize(int argc, char *argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_RGBA); glutInitWindowPosition(100, 100); glutInitWindowSize(600, 600); glutCreateWindow("OpenGL Lab1"); Set_Transformations(); glutDisplayFunc(Draw); glutMouseFunc(MouseClick); glutKeyboardFunc(OnKeyPress); glutMainLoop(); } void Set_Transformations() { glClearColor(1, 1, 1, 1); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(-200, 200, -200, 200); } void OnKeyPress(unsigned char key, int x, int y) { if (key == 27) exit(0); switch(key) { case 13: //enter key it will draw done = true; glutPostRedisplay(); flag=!flag; // this flag to switch to the other array that the vertices will be stored in, in order to draw the second polygon break; } } void MouseClick(int button, int state , int x , int y) { switch (button) { case GLUT_RIGHT_BUTTON: if (state == GLUT_DOWN) { if (count>0) { DeleteVer(); //dont mind this right now } } break; case GLUT_LEFT_BUTTON: if (state == GLUT_DOWN) { if(count<20) { if(flag =true){ // drawing first polygon GetOGLPos(x, y,xPos,yPos);} if (flag=false) //drawing second polygon after Enter is pressed GetOGLPos(x, y,xPos2,yPos2); } } break; } } void GetOGLPos(int x, int y,float* arrY,float* arrX) //getting the vertices from the user { GLint viewport[4]; GLdouble modelview[16]; GLdouble projection[16]; GLfloat winX, winY, winZ; GLdouble posX, posY, posZ; glGetDoublev( GL_MODELVIEW_MATRIX, modelview ); glGetDoublev( GL_PROJECTION_MATRIX, projection ); glGetIntegerv( GL_VIEWPORT, viewport ); winX = (float)x; winY = (float)viewport[3] - (float)y; glReadPixels( x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ ); gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ); arrX[count] = posX; arrY[count] = posY; count++; glPointSize( 6.0 ); glBegin(GL_POINTS); glVertex2f(posX,posY); glEnd(); glFlush(); } void DeleteVer(){ //dont mind this glColor3f ( 1, 1, 1); glBegin(GL_POINTS); glVertex2f(xPos[count-1],yPos[count-1]); glEnd(); glFlush(); xPos[count] = NULL; yPos[count] = NULL; count--; glColor3f ( 0, 0, 0); } void DrawPolygon(float* arrX,float* arrY) { int n=0; glColor3f ( 0, 0, 0); glBegin(GL_POLYGON); while(n<count) { glVertex2f(arrX[n],arrY[n]); n++; } count=0; glEnd(); glFlush(); } void Draw() //main drawing func { glClear(GL_COLOR_BUFFER_BIT); glColor3f(0, 0, 0); if(done) { DrawPolygon(xPos,yPos); DrawPolygon(xPos2,yPos2); } glFlush(); } int main(int argc, char *argv[]) { Initialize(argc, argv); return 0; }

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