fbo | 易学教程

Ping-pong rendering between two FBOs fails after first frame.

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I am trying to create two FBOs and implement a ping-pong render. But, I only get the first frame to work properly. I am trying to simulate a game-of-life and, after the first frame, I only get a black screen. Could you help me check it? I have spent hours on this issue. Edit Maybe I didn't describe clearly. Actually, I want to use the textureB as the texture and render it to textureA, then use the textureA to render to screen, then vice versa. Edit I can see the first frame, which is the textureB. After it go through the fragment shader, it become black. At first, I suspect the fragment shader

Can an OpenGLES 2.0 framebuffer be bound to a texture and a renderbuffer at the same time?

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Brad Larson provides some great code here and here for 'rendering your scene into a texture-backed framebuffer', but it's not clear whether this is the same framebuffer that I use for the rest of the drawing. If you attach a renderbuffer to a framebuffer, can the framebuffer also render into a texture with the same call? Arttu Peltonen Sounds like you might be a bit confused with FBO usage. If you need it, this should get you started: Apple Developer - Drawing offscreen . This could help too. Renderbuffer is something you can bind to an FBO (framebuffer object). FBO is something you create

COLOR_ATTACHMENT's - How to render to multiple textures as color attachments inside a Framebuffer Object?

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I am trying to render to multiple textures as COLOR_ATTACHMENT s without success. All I get from displaying them is a black screen (with a red clear fill) meaning my texture is read but is 'empty'. My pseudo code is : attach 3 textures to an FBO with texture indexes 1, 2 and 3 and color attachments 0, 1 and 2 respectively. As a test case, I tried to render my scene to the 3 color attachments so they are supposed to hold the same exact data. Then read either of those textures at shader pass 2 (with a 2Dsampler) and display them on a quad. My original intent for those 2 extra color attachments

Render off screen (with FBO and RenderBuffer) and pixel transfer of color, depth, stencil

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问题 I'have to render off screen in OpenGL and then pass the image to a QImage. Plus, just for exercise I'd like to transfer to the CPU also the depth and the stencil buffer. For drawing offscreen I've used Frame Buffer Object with Render Buffer (and not with texture because I don't need the texture). Pixel transfer operation with color buffers (the actual raw image) works.. I see what I'm expecting. But depth and stencil are not working.. strange image for depth and nothing with for the stencil.

Draw the contents of the render buffer Object

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问题 Do not quite understand the operation render buffer object. For example if I want to show what is in the render buffer, I must necessarily do the render to texture? GLuint fbo,color_rbo,depth_rbo; glGenFramebuffers(1,&fbo); glBindFramebuffer(GL_FRAMEBUFFER,fbo); glGenRenderbuffersEXT(1, &color_rb); glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, color_rb); glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA8, 256, 256); glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,GL

OpenGL: Rendering to texture by using FBO and viewport offset problems

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I have noticed unexpected behavior of frame-buffer objects (FBO) when rendering to a texture. If we set viewport in following way: glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, 1.0, 1.0, 0.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity() ; (w and h doesn't need to match window size) everything is rendered fine: So lets say we need to draw bounding rectangle of viewport: glBegin(GL_LINE_STRIP); glVertex2f(0.0, 0.0); glVertex2f(0.0, 1.0); glVertex2f(1.0, 1.0); glVertex2f(1.0, 0.0); glEnd(); If we do the same drawing on a texture then covering whole

Opengl, DrawArrays without binding VBO

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问题 I am rendering array of points with a custom vertex shader. Shaders looks like: void mainVP() in varying int in_vertex_id : VERTEXID { foo(in_vertex_id); } So the only thing I need - is vertex id. But I need a lot of vertices and I don't want to store fake VBO for them (it takes around 16mb of memory). I tried to run my code without binding any VBO. It works. So my rendering looks like: size_t num_vertices = ... glDrawArrays(GL_POINTS, 0, num_vertices); But can I be sure that rendering

problem saving openGL FBO larger than window

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问题 I'm rendering into an OpenGL offscreen framebuffer object and like to save it as an image. Note that the FBO is larger than the display size. I can render into the offscreen buffer and use it as texture, which works. I can "scroll" this larger texture through the display using an offset, which makes me confident, that I render into a larger context than the window. If I save the offscreen buffer to an image file it always gets cropped. The code fragment for saving is: void ofFBOTexture:

FBO offscreen rendering slow

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I want to use offscreen rendering using openGL es 2.0 and GLSL shader I setup FBO and it seems working except there are two problems 1) The program goes about 30 fps but all the sudden, it drops to 20fps and then come back to 30 fps again, then few secs later, drops to 20fps again then come back to 30fps and so on...(keeps going on like that) and I don't know what cause this random pause/delay 2) When I close the application, it does not respond for awhile. In other words, it seems like there are some data to clean up or some delay...So when I close the program, it does not do so until few

OpenGL ES2.0 offscreen context for FBO rendering

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问题 I would like to do offscreen rendering (in console environment without any WS) with FBOs. I know that it is necessary to create an OpenGL context, and at least a dummy window for any operation, therefore I did the following initialization: // Step 1 - Get the default display. eglDisplay = eglGetDisplay((EGLNativeDisplayType)0); // Step 2 - Initialize EGL. EGLint iMajorVersion, iMinorVersion; if (!eglInitialize(eglDisplay, &iMajorVersion, &iMinorVersion)) { printf("Error: eglInitialize()