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  • Restoring projection matrix

    - by brainydexter
    I am learning to use FBOs and one of the things that I need to do when rendering something onto user defined FBO, I have to setup the projection, modelview and viewport for it. Once I am done rendering to the FBO, I need to restore these matrices. I found: glPushAttrib(GL_VIEWPORT_BIT); glPopAttrib(); to restore the viewport to its old state. Is there a way to restore the projection and modelview matrix to whatever it was earlier ? Tech: C++/OpenGL Thanks!

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  • How can I downsample a texture using FBOs?

    - by snape
    I am rendering a scene to FBO as my render target whose size is 8 times the size of the orignal screen in OpenGL. Now i wan to downsample the texture generated by FBO to the size of the screen so as to achieve spatial anti aliasing. How do i achieve the down sampling ? Please provide implementation details. Note : If there is a better way of doing anti aliasing in FBOs please mention that too. I am trying to remove the aliasing in the image attached below.

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  • OpenGL ES 2.0. Sprite Sheet Animation

    - by Project Dumbo Dev
    I've found a bunch of tutorials on how to make this work on Open GL 1 & 1.1 but I can't find it for 2.0. I would work it out by loading the texture and use a matrix on the vertex shader to move through the sprite sheet. I'm looking for the most efficient way to do it. I've read that when you do the thing I'm proposing you are constantly changing the VBO's and that that is not good. Edit: Been doing some research myself. Came upon this two Updating Texture and referring to the one before PBO's. I can't use PBO's since i'm using ES version of OpenGL so I suppose the best way is to make FBO's but, what I still don't get, is if I should create a Sprite atlas/batch and make a FBO/loadtexture for each frame of if I should load every frame into the buffer and change just de texture directions.

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  • glFramebufferTexture2D performance

    - by nornagon
    I'm doing heavy computation using the GPU, which involves a lot of render-to-texture operations. It's an iterative computation, so there's a lot of rendering to a texture, then rendering that texture to another texture, then rendering the second texture back to the first texture and so on, passing the texture through a shader each time. My question is: is it better to have a separate FBO for each texture I want to render into, or should I rather have one FBO and bind the target texture using glFramebufferTexture2D each time I want to change render target? My platform is OpenGL ES 2.0 on the iPhone.

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  • OpenGL ES clarifying question regarding FBOs -- sorry can't find this info anywhere else?

    - by DevDevDev
    If I instantiate an FBO without binding a rendering buffer or a texture to it, what happens when I draw to it, nothing? Do I need to associate a rendering target (renderbuffer or texture) to have an FBO do anything? What I'm trying to do is precache some buffers and then merge them later, but that doesn't seem to work at all. Ideally I'd like to do something like glBindFramebufferOES(GL_FRAMEBUFFER_OES, fbo1); // Draw some stuff to fbo1 glBindFramebufferOES(GL_FRAMEBUFFER_OES, fbo2); // Draw some stuff to fbo2 // ... // ... // glRenderFbo(fbo1); -- Not a func // Set blending, etc. etc. // glRenderFbo(fbo2); -- Not a func

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  • Why, on iOS, is glRenderbufferStorage appearing to fail?

    - by dugla
    On an iOS device (iPad) I decided to change the storage for my renderbuffer from the CAEAGLLayer that backs the view to explicit storage via glRenderbufferStorage. Sadly, the following code fails to result in a valid FBO. Can someone please tell me what I missed?: glGenFramebuffers(1, &m_framebuffer); glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer); glGenRenderbuffers(1, &m_colorbuffer); glBindRenderbuffer(GL_RENDERBUFFER, m_colorbuffer); GLsizei width = (GLsizei)layer.bounds.size.width; GLsizei height = (GLsizei)layer.bounds.size.height; glRenderbufferStorage(m_colorbuffer, GL_RGBA8_OES, width, height); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, m_colorbuffer); Note: The layer size is valid and correct. This is solid production working rendering code. The only change I am making is the line glRenderbufferStorage(...) previously I did: [m_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer] Thanks, Doug

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  • Why am I seeing streak artifacts on the cube map I'm rendering?

    - by BobDole
    I'm getting strange streaks on my cube map when rendering to it. He is my code that is being called each frame: void drawCubeMap(void) { int face; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBindFramebuffer(GL_FRAMEBUFFER, fbo); //glBindTexture(GL_TEXTURE_CUBE_MAP, cubeMapTexture); //glClearColor(1.0f, 1.0f, 1.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glViewport(0,0,sizeT, sizeT); for (face = 0; face < 6; face++) { glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, cubeMapTexture, 0); drawSpheres(); } glBindFramebuffer(GL_FRAMEBUFFER, 0); glBindTexture(GL_TEXTURE_2D, 0); glViewport(0,0,900, 900); } Any idea what it might be? The streaking occurs when I'm rotating the spheres around the main sphere.

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  • forward rendering and multiple shadow maps

    - by Irbis
    I have two light sources on my scene. I created two fbo's which store depth textures for these lights. A render loop looks like this: bind fbo1 save depth values for first light unbind fbo1 bind fbo2 save depth values for second light unbind fbo2 enable additive blending bind first depth texture render scene bind second depth texture render scene disable additive blending For one light source the program works fine. For many light sources I use an additive blending to acumulate lighting results but then some objects become transparent (for example when an object which is further away from the camera is drawn before an object which is closer to the camera). How to resolve that problem ? How should I accumulate lighting effects for many light sources (many shadow maps) ? P.S. I use OpenGL/GLSL 3.3+

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  • JZ0SJ: Metadata accessor information was not found on this database.

    - by Anthony Kong
    The complete message is: (JZ0SJ: Metadata accessor information was not found on this database. Please install the required tables as mentioned in the jConnect documentation The server is Adaptive Server Enterprise/15.5/EBF 18380 SMP ESD#3/P/x86_64/Enterprise Linux/asear155/2531/64-bit/FBO/Fri Jan 14 07:04:05 2011 Google search does not turn up definite answer to the problem. A lof of result are rather dated too. I checked the documentation but it does not mention any tables. What is the root cause of this problem? At the very least I would like to see a list of the required tables somewhere?

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  • GetData() error creating framebuffer

    - by Lelezeus
    I'm currently porting a game written in C# with XNA library to Android with Monogame. I have a Texture2D and i'm trying to get an array of uint in this way: Texture2d textureDeform = game.Content.Load<Texture2D>("Texture/terrain"); uint[] pixelDeformData = new uint[textureDeform.Width * textureDeform.Height]; textureDeform.GetData(pixelDeformData, 0, textureDeform.Width * textureDeform.Height); I get the following exception: System.Exception: Error creating framebuffer: Zero at Microsoft.Xna.Framework.Graphics.Texture2D.GetTextureData (Int32 ThreadPriorityLevel) [0x00000] in :0 I found that the problem is in private byte[] GetTextureData(int ThreadPriorityLevel) creating the framebuffer: private byte[] GetTextureData(int ThreadPriorityLevel) { int framebufferId = -1; int renderBufferID = -1; GL.GenFramebuffers(1, ref framebufferId); // framebufferId is still -1 , why can't be created? GraphicsExtensions.CheckGLError(); GL.BindFramebuffer(All.Framebuffer, framebufferId); GraphicsExtensions.CheckGLError(); //renderBufferIDs = new int[currentRenderTargets]; GL.GenRenderbuffers(1, ref renderBufferID); GraphicsExtensions.CheckGLError(); // attach the texture to FBO color attachment point GL.FramebufferTexture2D(All.Framebuffer, All.ColorAttachment0, All.Texture2D, this.glTexture, 0); GraphicsExtensions.CheckGLError(); // create a renderbuffer object to store depth info GL.BindRenderbuffer(All.Renderbuffer, renderBufferID); GraphicsExtensions.CheckGLError(); GL.RenderbufferStorage(All.Renderbuffer, All.DepthComponent24Oes, Width, Height); GraphicsExtensions.CheckGLError(); // attach the renderbuffer to depth attachment point GL.FramebufferRenderbuffer(All.Framebuffer, All.DepthAttachment, All.Renderbuffer, renderBufferID); GraphicsExtensions.CheckGLError(); All status = GL.CheckFramebufferStatus(All.Framebuffer); if (status != All.FramebufferComplete) throw new Exception("Error creating framebuffer: " + status); ... } The frameBufferId is still -1, seems that framebuffer could not be generated and I don't know why. Any help would be appreciated, thank you in advance.

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  • (LWJGL) Pixel Unpack Buffer Object is Disabled? (glTextImage2D)

    - by OstlerDev
    I am trying to create a render target for my game so that I can re-render at a different screen size. But I am receiving the following error: Exception in thread "main" org.lwjgl.opengl.OpenGLException: Cannot use offsets when Pixel Unpack Buffer Object is disabled Here is the source code for my Render method: // clear screen GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); // Start FBO Rendering Code // The framebuffer, which regroups 0, 1, or more textures, and 0 or 1 depth buffer. int FramebufferName = GL30.glGenFramebuffers(); GL30.glBindFramebuffer(GL30.GL_FRAMEBUFFER, FramebufferName); // The texture we're going to render to int renderedTexture = glGenTextures(); // "Bind" the newly created texture : all future texture functions will modify this texture glBindTexture(GL_TEXTURE_2D, renderedTexture); // Give an empty image to OpenGL ( the last "0" ) glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, 1024, 768, 0,GL_RGB, GL_UNSIGNED_BYTE, 0); // Poor filtering. Needed ! glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); // Set "renderedTexture" as our colour attachement #0 GL32.glFramebufferTexture(GL30.GL_FRAMEBUFFER, GL30.GL_COLOR_ATTACHMENT0, renderedTexture, 0); // Set the list of draw buffers. IntBuffer drawBuffer = BufferUtils.createIntBuffer(20 * 20); GL20.glDrawBuffers(drawBuffer); // Always check that our framebuffer is ok if(GL30.glCheckFramebufferStatus(GL30.GL_FRAMEBUFFER) != GL30.GL_FRAMEBUFFER_COMPLETE){ System.out.println("Framebuffer was not created successfully! Exiting!"); return; } // Resets the current viewport GL11.glViewport(0, 0, scaleWidth*scale, scaleHeight*scale); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glLoadIdentity(); // let subsystem paint if (callback != null) { callback.frameRendering(); } // update window contents Display.update(); It is crashing on this line: glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, 1024, 768, 0,GL_RGB, GL_UNSIGNED_BYTE, 0); I am not really sure why it is crashing and looking around I have not been able to find out why. Any help or insight would be greatly welcome.

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  • OpenGL render to texture causing edge artifacts

    - by mysticalOso
    This is my first post here so any help would be massively appreciated :) I'm using C++ with SDL and OpenGL 3.3 When rendering directly to screen I get the following result And when I render to texture I this happens Anti-aliasing is turned off for both. I'm guessing this has something to do with depth buffer accuracy but I've tried a lot of different methods to improve the result but, no success :( I'm currently using the following code to set up my FBO: GLuint frameBufferID; glGenFramebuffers(1, &frameBufferID); glBindFramebuffer(GL_FRAMEBUFFER, frameBufferID); glGenTextures(1, &coloursTextureID); glBindTexture(GL_TEXTURE_2D, coloursTextureID); glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,SCREEN_WIDTH,SCREEN_HEIGHT,0,GL_RGB,GL_UNSIGNED_BYTE,NULL); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_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); //Depth buffer setup GLuint depthrenderbuffer; glGenRenderbuffers(1, &depthrenderbuffer); glBindRenderbuffer(GL_RENDERBUFFER, depthrenderbuffer); glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, SCREEN_WIDTH,SCREEN_HEIGHT); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthrenderbuffer); glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, coloursTextureID, 0); GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0}; glDrawBuffers(1, DrawBuffers); // if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) return false; Thank you so much for any help :)

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  • Failing Screen Resize Method

    - by StrongJoshua
    So I want my game to draw to a specific "optimal" size and then be stretched to fit screens that are a different size. I'm using LibGDX and figured that I could just draw everything to a FrameBuffer and then resize that buffer to the appropriate size when drawing it to the actual display. However, my method does not work, it just results in a black screen with the top right quarter of the screen white.Intermediary is the FBO, interMatrix is a Matrix4 object, and camera is an OrthographicCamera. @Override public void render() { // update actors currentStage.act(); //render to intermediary buffer batch.setProjectionMatrix(interMatrix); intermediary.begin(); batch.begin(); currentStage.draw(); batch.flush(); intermediary.end(); //resize to actual width and height Sprite s = new Sprite(intermediary.getColorBufferTexture()); s.flip(true, false); batch.setProjectionMatrix(camera.combined); batch.draw(s.getTexture(), 0, 0, width, height); batch.end(); } These are the constructors for the above mentioned objects (GAME_WIDTH and HEIGHT are the "optimal" settings, width and height are the actual sizes, which are the same when running on desktop). intermediary = new FrameBuffer(Format.RGBA8888, GAME_WIDTH, GAME_HEIGHT, false); interMatrix = new Matrix4(); camera = new OrthographicCamera(width, height); interMatrix.setToOrtho2D(0, 0, GAME_WIDTH, GAME_HEIGHT); Is there a better way of doing this or can is this a viable option and how do I fix what I have?

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  • OpenGL depth texture wrong

    - by CoffeeandCode
    I have been writing a game engine for a while now and have decided to reconstruct my positions from depth... but how I read the depth seems to be wrong :/ What is wrong in my rendering? How I init my depth texture in the FBO gl::BindTexture(gl::TEXTURE_2D, this->textures[0]); // Depth gl::TexImage2D( gl::TEXTURE_2D, 0, gl::DEPTH32F_STENCIL8, width, height, 0, gl::DEPTH_STENCIL, gl::FLOAT_32_UNSIGNED_INT_24_8_REV, nullptr ); gl::TexParameterf(gl::TEXTURE_2D, gl::TEXTURE_MAG_FILTER, gl::NEAREST); gl::TexParameterf(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::NEAREST); gl::TexParameterf(gl::TEXTURE_2D, gl::TEXTURE_WRAP_S, gl::CLAMP_TO_EDGE); gl::TexParameterf(gl::TEXTURE_2D, gl::TEXTURE_WRAP_T, gl::CLAMP_TO_EDGE); gl::FramebufferTexture2D( gl::FRAMEBUFFER, gl::DEPTH_STENCIL_ATTACHMENT, gl::TEXTURE_2D, this->textures[0], 0 ); Linear depth readings in my shader Vertex #version 150 layout(location = 0) in vec3 position; layout(location = 1) in vec2 uv; out vec2 uv_f; void main(){ uv_f = uv; gl_Position = vec4(position, 1.0); } Fragment (where the issue probably is) #version 150\n uniform sampler2D depth_texture; in vec2 uv_f; out vec4 Screen; void main(){ float n = 0.00001; float f = 100.0; float z = texture(depth_texture, uv_f).x; float linear_depth = (n * z)/(f - z * (f - n)); Screen = vec4(linear_depth); // It ISN'T because I don't separate alpha } When Rendered so gamedev.stackexchange, what's wrong with my rendering/glsl?

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  • Android OpenGL ES 2 framebuffer not working properly

    - by user16547
    I'm trying to understand how framebuffers work. In order to achieve that, I want to draw a very basic triangle to a framebuffer texture and then draw the resulting texture to a quad on the default framebuffer. However, I only get a fraction of the triangle like below. LE: The triangle's coordinates should be (1) -0.5f, -0.5f, 0 (2) 0.5f, -0.5f, 0 (3) 0, 0.5f, 0 Here's the code to render: @Override public void onDrawFrame(GL10 gl) { renderNormalStuff(); renderFramebufferTexture(); } protected void renderNormalStuff() { GLES20.glViewport(0, 0, texWidth, texHeight); GLUtils.updateProjectionMatrix(mProjectionMatrix, texWidth, texHeight); GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fbo[0]); GLES20.glUseProgram(mProgram); GLES20.glClearColor(.5f, .5f, .5f, 1); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT); Matrix.setIdentityM(mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); GLES20.glUniformMatrix4fv(u_MVPMatrix, 1, false, mMVPMatrix, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo[0]); GLES20.glVertexAttribPointer(a_Position, 3, GLES20.GL_FLOAT, false, 12, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo[1]); GLES20.glVertexAttribPointer(a_Color, 4, GLES20.GL_FLOAT, false, 16, 0); GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, ibo[0]); GLES20.glDrawElements(GLES20.GL_TRIANGLES, indexBuffer.capacity(), GLES20.GL_UNSIGNED_BYTE, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0); GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0); GLES20.glUseProgram(0); } private void renderFramebufferTexture() { GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0); GLES20.glUseProgram(fboProgram); GLES20.glClearColor(.0f, .5f, .25f, 1); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); GLES20.glViewport(0, 0, width, height); GLUtils.updateProjectionMatrix(mProjectionMatrix, width, height); Matrix.setIdentityM(mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); GLES20.glUniformMatrix4fv(fbo_u_MVPMatrix, 1, false, mMVPMatrix, 0); //draw the texture GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture[0]); GLES20.glUniform1i(fbo_u_Texture, 0); GLUtils.sendBufferData(fbo_a_Position, 3, quadPositionBuffer); GLUtils.sendBufferData(fbo_a_TexCoordinate, 2, quadTexCoordinate); GLES20.glDrawElements(GLES20.GL_TRIANGLES, quadIndexBuffer.capacity(), GLES20.GL_UNSIGNED_BYTE, quadIndexBuffer); GLES20.glUseProgram(0); }

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  • GPGPU programming with OpenGL ES 2.0

    - by Albus Dumbledore
    I am trying to do some image processing on the GPU, e.g. median, blur, brightness, etc. The general idea is to do something like this framework from GPU Gems 1. I am able to write the GLSL fragment shader for processing the pixels as I've been trying out different things in an effect designer app. I am not sure however how I should do the other part of the task. That is, I'd like to be working on the image in image coords and then outputting the result to a texture. I am aware of the gl_FragCoords variable. As far as I understand it it goes like that: I need to set up a view (an orthographic one maybe?) and a quad in such a way so that the pixel shader would be applied once to each pixel in the image and so that it would be rendering to a texture or something. But how can I achieve that considering there's depth that may make things somewhat awkward to me... I'd be very grateful if anyone could help me with this rather simple task as I am really frustrated with myself. UPDATE It seems I'll have to use an FBO, getting one like this: glBindFramebuffer(...)

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  • EAGLContext, EAGLSharegroups, RenderBuffers, FrameBuffers, oh my!

    - by quixoto
    Hi all, I'm trying to wrap my head around the OpenGL object model on iPhone OS. I'm currently rendering into a few different UIViews (build on CAEAGLayers) on the screen. I currently have each of these as using separate EAGLContext, each of which has a color renderbuffer and a framebuffer. I'm rendering similar things in them, and I'd like to share textures between these instances to save memory overhead. My current understanding is that I could use the same setup (some number of contexts, each with a FBO/RBO) but if I spawn the later ones using the EAGLShareGroup of the first one, then I can simply use the texture names (GLuints) from the first one in the later ones. Is this accurate? If this is the case, I guess the followup question is: what's the benefit to having it be a "sharegroup"? Could I just reuse the same context, and attach multiple FBOs/RBOs to that context? I think I'm struggling with the abstraction layer of a sharegroup, which seems to share "objects" (textures and other named things) but not "state" (matrices, enabled/disabled states) which are owned by the context. What's the best way to think of this? Thanks for any enlightenment!

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  • iPhone OpenGL ES Texture2D Masking

    - by Robert Neagu
    What's the best choice when trying to mask a texture like ColorSplash or other apps like iSteam, etc? I started learning OPENGL ES like... 4 days ago (I'm a total rookie) and tried the following approach: 1) I created a colored texture2D, a grayscale version of the first texture and a third texture2D called mask 2) I also created a texture2D for the brush... which is grayscale and it's opaque (brush = black = 0,0,0,1 and surroundings = white = 1,1,1,1). My intention was to create an antialiased brush with smooth edges but i'm fine with a normal one right now 3) I searched for masking techniques on the internet and found this tutorial ZeusCMD - Design and Development Tutorials : OpenGL ES Programming Tutorials - Masking about masking. The tutorial tells me to use blending to achieve masking... first draw colored, then mask with glBlendFunc(GL_DST_COLOR, GL_ZERO) and then grayscale with glBlendFunc(GL_ONE, GL_ONE) ... and this gives me something close to what i want... but not exactly what i want. The result is masked but it's somehow overbright-ed 4) For drawing to the mask texture i used an extra frame buffer object (FBO) I'm not really happy with the resulting image (overbright-ed picture) nor with the speed achieved with this method. I think the normal way was to draw directly to the grayscale (overlay) texture2D affecting only it's alpha channel in the places where the brush hits. Is there a fast way to achieve this? I have searched a lot and never got an answer that's clear and understandable. Then, in the main draw loop I could only draw the colored texture and then blend the grayscale ontop with glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). I just want to learn to use OPENGL ES and it's driving me nuts because i can't get it to work properly. An advice, a link to a tutorial would be much appreciated.

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  • gl_FragColor and glReadPixels

    - by chun0216
    I am still trying to read pixels from fragment shader and I have some questions. I know that gl_FragColor returns with vec4 meaning RGBA, 4 channels. After that, I am using glReadPixels to read FBO and write it in data GLubyte *pixels = new GLubyte[640*480*4]; glReadPixels(0, 0, 640,480, GL_RGBA, GL_UNSIGNED_BYTE, pixels); This works fine but it really has speed issue. Instead of this, I want to just read RGB so ignore alpha channels. I tried: GLubyte *pixels = new GLubyte[640*480*3]; glReadPixels(0, 0, 640,480, GL_RGB, GL_UNSIGNED_BYTE, pixels); instead and this didn't work though. I guess it's because gl_FragColor returns 4 channels and maybe I should do something before this? Actually, since my returned image (gl_FragColor) is grayscale, I did something like float gray = 0.5 //or some other values gl_FragColor = vec4(gray,gray,gray,1.0); So is there any efficient way to use glReadPixels instead of using the first 4 channels method? Any suggestion? By the way, this is on opengl es 2.0 code.

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  • Unable to get Stencil Buffer to work in iOS 4+ (5.0 works fine). [OpenGL ES 2.0]

    - by MurderDev
    So I am trying to use a stencil buffer in iOS for masking/clipping purposes. Do you guys have any idea why this code may not work? This is everything I have associated with Stencils. On iOS 4 I get a black screen. On iOS 5 I get exactly what I expect. The transparent areas of the image I drew in the stencil are the only areas being drawn later. Code is below. This is where I setup the frameBuffer, depth and stencil. In iOS the depth and stencil are combined. -(void)setupDepthBuffer { glGenRenderbuffers(1, &depthRenderBuffer); glBindRenderbuffer(GL_RENDERBUFFER, depthRenderBuffer); glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, self.frame.size.width * [[UIScreen mainScreen] scale], self.frame.size.height * [[UIScreen mainScreen] scale]); } -(void)setupFrameBuffer { glGenFramebuffers(1, &frameBuffer); glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthRenderBuffer); // Check the FBO. if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) { NSLog(@"Failure with framebuffer generation: %d", glCheckFramebufferStatus(GL_FRAMEBUFFER)); } } This is how I am setting up and drawing the stencil. (Shader code below.) glEnable(GL_STENCIL_TEST); glDisable(GL_DEPTH_TEST); glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glDepthMask(GL_FALSE); glStencilFunc(GL_ALWAYS, 1, -1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glColorMask(0, 0, 0, 0); glClear(GL_STENCIL_BUFFER_BIT); machineForeground.shader = [StencilEffect sharedInstance]; [machineForeground draw]; machineForeground.shader = [BasicEffect sharedInstance]; glDisable(GL_STENCIL_TEST); glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); glDepthMask(GL_TRUE); Here is where I am using the stencil. glEnable(GL_STENCIL_TEST); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); glStencilFunc(GL_EQUAL, 1, -1); ...Draw Stuff here glDisable(GL_STENCIL_TEST); Finally here is my fragment shader. varying lowp vec2 TexCoordOut; uniform sampler2D Texture; void main(void) { lowp vec4 color = texture2D(Texture, TexCoordOut); if(color.a < 0.1) gl_FragColor = color; else discard; }

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  • Render To Texture Using OpenGL is not working but normal rendering works just fine

    - by Franky Rivera
    things I initialize at the beginning of the program I realize not all of these pertain to my issue I just copy and pasted what I had //overall initialized //things openGL related I initialize earlier on in the project glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClearDepth( 1.0f ); glEnable(GL_ALPHA_TEST); glEnable( GL_STENCIL_TEST ); glEnable(GL_DEPTH_TEST); glDepthFunc( GL_LEQUAL ); glEnable(GL_CULL_FACE); glFrontFace( GL_CCW ); glEnable(GL_COLOR_MATERIAL); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST ); //we also initialize our shader programs //(i added some shader program functions for definitions) //this enum list is else where in code //i figured it would help show you guys more about my //shader compile creation function right under this enum list VVVVVV /*enum eSHADER_ATTRIB_LOCATION { VERTEX_ATTRIB = 0, NORMAL_ATTRIB = 2, COLOR_ATTRIB, COLOR2_ATTRIB, FOG_COORD, TEXTURE_COORD_ATTRIB0 = 8, TEXTURE_COORD_ATTRIB1, TEXTURE_COORD_ATTRIB2, TEXTURE_COORD_ATTRIB3, TEXTURE_COORD_ATTRIB4, TEXTURE_COORD_ATTRIB5, TEXTURE_COORD_ATTRIB6, TEXTURE_COORD_ATTRIB7 }; */ //if we fail making our shader leave if( !testShader.CreateShader( "SimpleShader.vp", "SimpleShader.fp", 3, VERTEX_ATTRIB, "vVertexPos", NORMAL_ATTRIB, "vNormal", TEXTURE_COORD_ATTRIB0, "vTexCoord" ) ) return false; if( !testScreenShader.CreateShader( "ScreenShader.vp", "ScreenShader.fp", 3, VERTEX_ATTRIB, "vVertexPos", NORMAL_ATTRIB, "vNormal", TEXTURE_COORD_ATTRIB0, "vTexCoord" ) ) return false; SHADER PROGRAM FUNCTIONS bool CShaderProgram::CreateShader( const char* szVertexShaderName, const char* szFragmentShaderName, ... ) { //here are our handles for the openGL shaders int iGLVertexShaderHandle = -1, iGLFragmentShaderHandle = -1; //get our shader data char *vData = 0, *fData = 0; int vLength = 0, fLength = 0; LoadShaderFile( szVertexShaderName, &vData, &vLength ); LoadShaderFile( szFragmentShaderName, &fData, &fLength ); //data if( !vData ) return false; //data if( !fData ) { delete[] vData; return false; } //create both our shader objects iGLVertexShaderHandle = glCreateShader( GL_VERTEX_SHADER ); iGLFragmentShaderHandle = glCreateShader( GL_FRAGMENT_SHADER ); //well we got this far so we have dynamic data to clean up //load vertex shader glShaderSource( iGLVertexShaderHandle, 1, (const char**)(&vData), &vLength ); //load fragment shader glShaderSource( iGLFragmentShaderHandle, 1, (const char**)(&fData), &fLength ); //we are done with our data delete it delete[] vData; delete[] fData; //compile them both glCompileShader( iGLVertexShaderHandle ); //get shader status int iShaderOk; glGetShaderiv( iGLVertexShaderHandle, GL_COMPILE_STATUS, &iShaderOk ); if( iShaderOk == GL_FALSE ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLVertexShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLVertexShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szVertexShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLVertexShaderHandle); return false; } glCompileShader( iGLFragmentShaderHandle ); //get shader status glGetShaderiv( iGLFragmentShaderHandle, GL_COMPILE_STATUS, &iShaderOk ); if( iShaderOk == GL_FALSE ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLFragmentShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLFragmentShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szFragmentShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLFragmentShaderHandle); return false; } //lets check to see if the fragment shader compiled int iCompiled = 0; glGetShaderiv( iGLVertexShaderHandle, GL_COMPILE_STATUS, &iCompiled ); if( !iCompiled ) { //this shader did not compile leave return false; } //lets check to see if the fragment shader compiled glGetShaderiv( iGLFragmentShaderHandle, GL_COMPILE_STATUS, &iCompiled ); if( !iCompiled ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLFragmentShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLFragmentShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szFragmentShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLFragmentShaderHandle); return false; } //make our new shader program m_iShaderProgramHandle = glCreateProgram(); glAttachShader( m_iShaderProgramHandle, iGLVertexShaderHandle ); glAttachShader( m_iShaderProgramHandle, iGLFragmentShaderHandle ); glLinkProgram( m_iShaderProgramHandle ); int iLinked = 0; glGetProgramiv( m_iShaderProgramHandle, GL_LINK_STATUS, &iLinked ); if( !iLinked ) { //we didn't link return false; } //NOW LETS CREATE ALL OUR HANDLES TO OUR PROPER LIKING //start from this parameter va_list parseList; va_start( parseList, szFragmentShaderName ); //read in number of variables if any unsigned uiNum = 0; uiNum = va_arg( parseList, unsigned ); //for loop through our attribute pairs int enumType = 0; for( unsigned x = 0; x < uiNum; ++x ) { //specify our attribute locations enumType = va_arg( parseList, int ); char* name = va_arg( parseList, char* ); glBindAttribLocation( m_iShaderProgramHandle, enumType, name ); } //end our list parsing va_end( parseList ); //relink specify //we have custom specified our attribute locations glLinkProgram( m_iShaderProgramHandle ); //fill our handles InitializeHandles( ); //everything went great return true; } void CShaderProgram::InitializeHandles( void ) { m_uihMVP = glGetUniformLocation( m_iShaderProgramHandle, "mMVP" ); m_uihWorld = glGetUniformLocation( m_iShaderProgramHandle, "mWorld" ); m_uihView = glGetUniformLocation( m_iShaderProgramHandle, "mView" ); m_uihProjection = glGetUniformLocation( m_iShaderProgramHandle, "mProjection" ); ///////////////////////////////////////////////////////////////////////////////// //texture handles m_uihDiffuseMap = glGetUniformLocation( m_iShaderProgramHandle, "diffuseMap" ); if( m_uihDiffuseMap != -1 ) { //store what texture index this handle will be in the shader glUniform1i( m_uihDiffuseMap, RM_DIFFUSE+GL_TEXTURE0 ); (0)+ } m_uihNormalMap = glGetUniformLocation( m_iShaderProgramHandle, "normalMap" ); if( m_uihNormalMap != -1 ) { //store what texture index this handle will be in the shader glUniform1i( m_uihNormalMap, RM_NORMAL+GL_TEXTURE0 ); (1)+ } } void CShaderProgram::SetDiffuseMap( const unsigned& uihDiffuseMap ) { (0)+ glActiveTexture( RM_DIFFUSE+GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D, uihDiffuseMap ); } void CShaderProgram::SetNormalMap( const unsigned& uihNormalMap ) { (1)+ glActiveTexture( RM_NORMAL+GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D, uihNormalMap ); } //MY 2 TEST SHADERS also my math order is correct it pertains to my matrix ordering in my math library once again i've tested the basic rendering. rendering to the screen works fine ----------------------------------------SIMPLE SHADER------------------------------------- //vertex shader looks like this #version 330 in vec3 vVertexPos; in vec3 vNormal; in vec2 vTexCoord; uniform mat4 mWorld; // Model Matrix uniform mat4 mView; // Camera View Matrix uniform mat4 mProjection;// Camera Projection Matrix out vec2 vTexCoordVary; // Texture coord to the fragment program out vec3 vNormalColor; void main( void ) { //pass the texture coordinate vTexCoordVary = vTexCoord; vNormalColor = vNormal; //calculate our model view projection matrix mat4 mMVP = (( mWorld * mView ) * mProjection ); //result our position gl_Position = vec4( vVertexPos, 1 ) * mMVP; } //fragment shader looks like this #version 330 in vec2 vTexCoordVary; in vec3 vNormalColor; uniform sampler2D diffuseMap; uniform sampler2D normalMap; out vec4 fragColor[2]; void main( void ) { //CORRECT fragColor[0] = texture( normalMap, vTexCoordVary ); fragColor[1] = vec4( vNormalColor, 1.0 ); }; ----------------------------------------SCREEN SHADER------------------------------------- //vertext shader looks like this #version 330 in vec3 vVertexPos; // This is the position of the vertex coming in in vec2 vTexCoord; // This is the texture coordinate.... out vec2 vTexCoordVary; // Texture coord to the fragment program void main( void ) { vTexCoordVary = vTexCoord; //set our position gl_Position = vec4( vVertexPos.xyz, 1.0f ); } //fragment shader looks like this #version 330 in vec2 vTexCoordVary; // Incoming "varying" texture coordinate uniform sampler2D diffuseMap;//the tile detail texture uniform sampler2D normalMap; //the normal map from earlier out vec4 vTheColorOfThePixel; void main( void ) { //CORRECT vTheColorOfThePixel = texture( normalMap, vTexCoordVary ); }; .Class RenderTarget Main Functions //here is my render targets create function bool CRenderTarget::Create( const unsigned uiNumTextures, unsigned uiWidth, unsigned uiHeight, int iInternalFormat, bool bDepthWanted ) { if( uiNumTextures <= 0 ) return false; //generate our variables glGenFramebuffers(1, &m_uifboHandle); // Initialize FBO glBindFramebuffer(GL_FRAMEBUFFER, m_uifboHandle); m_uiNumTextures = uiNumTextures; if( bDepthWanted ) m_uiNumTextures += 1; m_uiTextureHandle = new unsigned int[uiNumTextures]; glGenTextures( uiNumTextures, m_uiTextureHandle ); for( unsigned x = 0; x < uiNumTextures-1; ++x ) { glBindTexture( GL_TEXTURE_2D, m_uiTextureHandle[x]); // Reserve space for our 2D render target glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, iInternalFormat, uiWidth, uiHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL); glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + x, GL_TEXTURE_2D, m_uiTextureHandle[x], 0); } //if we need one for depth testing if( bDepthWanted ) { glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, m_uiTextureHandle[uiNumTextures-1], 0); glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, m_uiTextureHandle[uiNumTextures-1], 0);*/ // Must attach texture to framebuffer. Has Stencil and depth glBindRenderbuffer(GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); glRenderbufferStorage(GL_RENDERBUFFER, /*GL_DEPTH_STENCIL*/GL_DEPTH24_STENCIL8, TEXTURE_WIDTH, TEXTURE_HEIGHT ); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); } glBindFramebuffer(GL_FRAMEBUFFER, 0); //everything went fine return true; } void CRenderTarget::Bind( const int& iTargetAttachmentLoc, const unsigned& uiWhichTexture, const bool bBindFrameBuffer ) { if( bBindFrameBuffer ) glBindFramebuffer( GL_FRAMEBUFFER, m_uifboHandle ); if( uiWhichTexture < m_uiNumTextures ) glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + iTargetAttachmentLoc, m_uiTextureHandle[uiWhichTexture], 0); } void CRenderTarget::UnBind( void ) { //default our binding glBindFramebuffer( GL_FRAMEBUFFER, 0 ); } //this is all in a test project so here's my straight forward rendering function for testing this render function does basic rendering steps keep in mind i have already tested my textures i have already tested my box thats being rendered all basic rendering works fine its just when i try to render to a texture then display it in a render surface that it does not work. Also I have tested my render surface it is bound exactly to the screen coordinate space void TestRenderSteps( void ) { //Clear the color and the depth glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); //bind the shader program glUseProgram( testShader.m_iShaderProgramHandle ); //1) grab the vertex buffer related to our rendering glBindBuffer( GL_ARRAY_BUFFER, CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().GetBufferHandle() ); //2) how our stream will be split here ( 4 bytes position, ..ext ) CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().MapVertexStride(); //3) set the index buffer if needed glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, CIndexBuffer::GetInstance()->GetBufferHandle() ); //send the needed information into the shader testShader.SetWorldMatrix( boxPosition ); testShader.SetViewMatrix( Static_Camera.GetView( ) ); testShader.SetProjectionMatrix( Static_Camera.GetProjection( ) ); testShader.SetDiffuseMap( iTextureID ); testShader.SetNormalMap( iTextureID2 ); GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 }; glDrawBuffers(2, buffers); //bind to our render target //RM_DIFFUSE, RM_NORMAL are enums (0 && 1) renderTarget.Bind( RM_DIFFUSE, 1, true ); renderTarget.Bind( RM_NORMAL, 1, false); //false because buffer is already bound //i clear here just to clear the texture to make it a default value of white //by doing this i can see if what im rendering to my screen is just drawing to the screen //or if its my render target defaulted glClearColor( 1.0f, 1.0f, 1.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); //i have this box object which i draw testBox.Draw(); //the draw call looks like this //my normal rendering works just fine so i know this draw is fine // glDrawElementsBaseVertex( m_sides[x].GetPrimitiveType(), // m_sides[x].GetPrimitiveCount() * 3, // GL_UNSIGNED_INT, // BUFFER_OFFSET(sizeof(unsigned int) * m_sides[x].GetStartIndex()), // m_sides[x].GetStartVertex( ) ); //we unbind the target back to default renderTarget.UnBind(); //i stop mapping my vertex format CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().UnMapVertexStride(); //i go back to default in using no shader program glUseProgram( 0 ); //now that everything is drawn to the textures //lets draw our screen surface and pass it our 2 filled out textures //NOW RENDER THE TEXTURES WE COLLECTED TO THE SCREEN QUAD //bind the shader program glUseProgram( testScreenShader.m_iShaderProgramHandle ); //1) grab the vertex buffer related to our rendering glBindBuffer( GL_ARRAY_BUFFER, CVertexBufferManager::GetInstance()->GetPositionTexBuffer().GetBufferHandle() ); //2) how our stream will be split here CVertexBufferManager::GetInstance()->GetPositionTexBuffer().MapVertexStride(); //3) set the index buffer if needed glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, CIndexBuffer::GetInstance()->GetBufferHandle() ); //pass our 2 filled out textures (in the shader im just using the diffuse //i wanted to see if i was rendering anything before i started getting into other techniques testScreenShader.SetDiffuseMap( renderTarget.GetTextureHandle(0) ); //SetDiffuseMap definitions in shader program class testScreenShader.SetNormalMap( renderTarget.GetTextureHandle(1) ); //SetNormalMap definitions in shader program class //DO the draw call drawing our screen rectangle glDrawElementsBaseVertex( m_ScreenRect.GetPrimitiveType(), m_ScreenRect.GetPrimitiveCount() * 3, GL_UNSIGNED_INT, BUFFER_OFFSET(sizeof(unsigned int) * m_ScreenRect.GetStartIndex()), m_ScreenRect.GetStartVertex( ) );*/ //unbind our vertex mapping CVertexBufferManager::GetInstance()->GetPositionTexBuffer().UnMapVertexStride(); //default to no shader program glUseProgram( 0 ); } Last words: 1) I can render my box just fine 2) i can render my screen rect just fine 3) I cannot render my box into a texture then display it into my screen rect 4) This entire project is just a test project I made to test different rendering practices. So excuse any "ugly-ish" unclean code. This was made just on a fly run through when I was trying new test cases.

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  • another question about OpenGL ES rendering to texture

    - by ensoreus
    Hello, pros and gurus! Here is another question about rendering to texture. The whole stuff is all about saving texture between passing image into different filters. Maybe all iPhone developers knows about Apple's sample code with OpenGL processing where they used GL filters(functions), but pass into them the same source image. I need to edit an image by passing it sequentelly with saving the state of the image to edit. I am very noob in OpenGL, so I spent increadibly a lot of to solve the issue. So, I desided to create 2 FBO's and attach source image and temporary image as a textures to render in. Here is my init routine: glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glGetIntegerv(GL_FRAMEBUFFER_BINDING_OES, (GLint *)&SystemFBO); glImage = [self loadTexture:preparedImage]; //source image for (int i = 0; i < 4; i++) { fullquad[i].s *= glImage->s; fullquad[i].t *= glImage->t; flipquad[i].s *= glImage->s; flipquad[i].t *= glImage->t; } tmpImage = [self loadEmptyTexture]; //editing image glGenFramebuffersOES(1, &tmpImageFBO); glBindFramebufferOES(GL_FRAMEBUFFER_OES, tmpImageFBO); glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, tmpImage->texID, 0); GLenum status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES); if(status != GL_FRAMEBUFFER_COMPLETE_OES) { NSLog(@"failed to make complete tmp framebuffer object %x", status); } glBindTexture(GL_TEXTURE_2D, 0); glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); glGenRenderbuffersOES(1, &glImageFBO); glBindFramebufferOES(GL_FRAMEBUFFER_OES, glImageFBO); glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, glImage->texID, 0); status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) ; if(status != GL_FRAMEBUFFER_COMPLETE_OES) { NSLog(@"failed to make complete cur framebuffer object %x", status); } glBindTexture(GL_TEXTURE_2D, 0); glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); When user drag the slider, this routine invokes to apply changes -(void)setContrast:(CGFloat)value{ contrast = value; if(flag!=mfContrast){ NSLog(@"contrast: dumped"); flag = mfContrast; glBindFramebufferOES(GL_FRAMEBUFFER_OES, glImageFBO); glClearColor(1,1,1,1); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(0, 512, 0, 512, -1, 1); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glScalef(512, 512, 1); glBindTexture(GL_TEXTURE_2D, tmpImage->texID); glViewport(0, 0, 512, 512); glVertexPointer(2, GL_FLOAT, sizeof(V2fT2f), &fullquad[0].x); glTexCoordPointer(2, GL_FLOAT, sizeof(V2fT2f), &fullquad[0].s); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); } glBindFramebufferOES(GL_FRAMEBUFFER_OES,tmpImageFBO); glClearColor(0,0,0,1); glClear(GL_COLOR_BUFFER_BIT); glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE0); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(0, 512, 0, 512, -1, 1); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glScalef(512, 512, 1); glBindTexture(GL_TEXTURE_2D, glImage->texID); glViewport(0, 0, 512, 512); [self contrastProc:fullquad value:contrast]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); [self redraw]; } Here are two cases: if it is the same filter(edit mode) to use, I bind tmpFBO to draw into tmpImage texture and edit glImage texture. contrastProc is a pure routine from Apples's sample. If it is another mode, than I save edited image by drawing tmpImage texture in source texture glImage, binded with glImageFBO. After that I call redraw: glBindFramebufferOES(GL_FRAMEBUFFER_OES, SystemFBO); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(0, kTexWidth, 0, kTexHeight, -1, 1); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glScalef(kTexWidth, kTexHeight, 1); glBindTexture(GL_TEXTURE_2D, glImage->texID); glViewport(0, 0, kTexWidth, kTexHeight); glVertexPointer(2, GL_FLOAT, sizeof(V2fT2f), &flipquad[0].x); glTexCoordPointer(2, GL_FLOAT, sizeof(V2fT2f), &flipquad[0].s); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0); And here it binds visual framebuffer and dispose glImage texture. So, the result is VERY aggresive filtering. Increasing contrast volume by just 0.2 brings image to state that comparable with 0.9 contrast volume in Apple's sample code project. I miss something obvious, I guess. Interesting, if I disabple line glBindTexture(GL_TEXTURE_2D, glImage->texID); in setContrast routine it brings no effect. At all. If I replace tmpImageFBO with SystemFBO to draw glImage directly on display(and disabling redraw invoking line), all works fine. Please, HELP ME!!! :(

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