Related
The goal of my program is to compare between the depth of the RGB-D camera and OpenGL depth.
The camera is facing a model (real one) and it has its own shaders (fragment and vertex).
To make comparison, a 3D Model is made, this one has also its own shaders (the depth is normally linearized as I followed what is explained in this tutorial: https://learnopengl.com/Advanced-OpenGL/Depth-testing).
So the comparison will be done on the depth received from the camera and the depth related to the 3D model.
So,the steps I have done are:
1.In the initialization function
Create two textures for each one (color and depth textures).
Generate two FBOs (one for the camera, the other one for the 3D Model).
Attach textures to their FBOs.
/* Other stuff needed for initialization */
...
// Generate color texture
glGenTextures(1, &colorTex);
glBindTexture(GL_TEXTURE_2D, colorTex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, _windowWidth, _windowHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glBindTexture(GL_TEXTURE_2D, 0);
// Generate depth texture
glGenTextures(1, &depthTex);
glBindTexture(GL_TEXTURE_2D, depthTex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, _windowWidth, _windowHeight, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glBindTexture(GL_TEXTURE_2D, 0);
// Attach the color and depth textures to current FrameBuffer
glGenFramebuffers(1, &_fboGL);
glBindFramebuffer(GL_FRAMEBUFFER, _fboGL);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthTex, 0);
In the main function for Drawing and rendering
Render the camera stream by binding its FBO.
Draw 3D Model by binding its own FBO.
Try to print openGL depth related to the 3D Model.
A fragment of the code looks like below:
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, camColorTex, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, camDepthTex, 0);
glViewport(0, 0, windowWidth, windowHeight);
glEnable(GL_DEPTH_TEST);
glClearColor(0.25f, 0.25f, 0.25f, 1.f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/*******************************************/
/* Some code for displaying camera stream */
/*******************************************/
.............
drawModelFunction();
printDepthFunction();
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, camColorTex, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, camDepthTex, 0);
/***********************************************************/
/* Some stuff to render a GUI to interact with the program */
/***********************************************************/
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
glBlitFramebuffer(0, 0, _windowWidth, _windowHeight, 0, 0, _windowWidth, _windowHeight, GL_COLOR_BUFFER_BIT, GL_LINEAR);
glBlitFramebuffer(0, 0, _windowWidth, _windowHeight, 0, 0, _windowWidth, _windowHeight, GL_DEPTH_BUFFER_BIT, GL_NEAREST);
A fragment code for drawModelFunction()
glBindFramebuffer(GL_FRAMEBUFFER, fboGL);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthTex, 0);
/*************************************/
/* Some stuff to render the 3D Model */
/*************************************/
A fragment code for printDepthFunction()
GLfloat *pixels = (GLfloat *)malloc(_windowWidth * _windowHeight * sizeof *pixels);
assert(pixels);
glBindTexture(GL_TEXTURE_2D, depthTex);
glGetTexImage(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, GL_FLOAT, pixels);
/* print the the values stored in **pixels** */
free(pixels);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
When I try to display the values stored in the depth, I only obtain one value "1.0f" and the color returns me only the value "0.0f". In addition to that, the rendering is not here as I mixed everything with FBOs. I have a screen with mixture of camera stream, a red square inserted in the middle of the screen with the GUI in it (that took the red color of the square). And No 3D Model. (This is the result I have obtained after binding the framebuffers everywhere like shown before).
I'd like to use the "render to texture" paradigm to write a .png screenshot of my OpenGL 3D rendering. I have it working without multi-sampling, but I'm struggling to get an anti-aliased image.
First of all, is this possible?
Second, what is the right combination of API calls?
(meta third question, how can I better debug this? glCheckFramebufferStatus is clearly not enough).
Here's what I'm working with:
// https://stackoverflow.com/questions/7402504/multisampled-render-to-texture-in-ios
GLuint texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA4, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
GLuint resolved_framebuffer, resolvedColorRenderbuffer;
glGenFramebuffers(1, &resolved_framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, resolved_framebuffer);
glGenRenderbuffers(1, &resolvedColorRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, resolvedColorRenderbuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
GLuint framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
GLuint colorRenderbuffer, depthRenderbuffer;
glGenRenderbuffers(1, &colorRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_RGBA8, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
glGenRenderbuffers(1, &depthRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH_COMPONENT16, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
glBindFramebuffer( GL_FRAMEBUFFER, framebuffer );
glClearColor(background_color(0), background_color(1), background_color(2), 0.f);
glClear(GL_COLOR_BUFFER_BIT);// | GL_DEPTH_BUFFER_BIT);
draw_scene();
glBindFramebuffer( GL_READ_FRAMEBUFFER, framebuffer );
glBindFramebuffer( GL_DRAW_FRAMEBUFFER, resolved_framebuffer );
// https://forum.juce.com/t/ios-8-getting-the-demo-building/13570/20
glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
// ^--- this is throwing `GL_INVALID_OPERATION`
GLubyte* pixels = (GLubyte*)calloc(width*height*4,sizeof(GLubyte));
glReadPixels(0, 0,width, height,GL_RGBA, GL_UNSIGNED_BYTE, pixels);
writePNG(pixels);
Currently I'm getting a blank image and glBlitFramebuffer is throwing GL_INVALID_OPERATION. Apparently this error can correspond to many things, and I'm not sure which is applying. My buffers seem "good" according to glCheckFramebufferStatus.
This question has been asked in similar forms before:
Cannot render to texture with multisampling
Multisampled render to texture in ios
But none of the answers have lead to a complete working example. I would love to find/create a minimal example of this.
The tutorial at https://learnopengl.com/Advanced-OpenGL/Anti-Aliasing basically had what I needed. The working solution is:
unsigned int framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
// create a multisampled color attachment texture
unsigned int textureColorBufferMultiSampled;
glGenTextures(1, &textureColorBufferMultiSampled);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, textureColorBufferMultiSampled);
glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGBA, width, height, GL_TRUE);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, textureColorBufferMultiSampled, 0);
// create a (also multisampled) renderbuffer object for depth and stencil attachments
unsigned int rbo;
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8, width, height);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo);
assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// configure second post-processing framebuffer
unsigned int intermediateFBO;
glGenFramebuffers(1, &intermediateFBO);
glBindFramebuffer(GL_FRAMEBUFFER, intermediateFBO);
// create a color attachment texture
unsigned int screenTexture;
glGenTextures(1, &screenTexture);
glBindTexture(GL_TEXTURE_2D, screenTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, screenTexture, 0); // we only need a color buffer
assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
draw_scene();
glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, intermediateFBO);
glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
glBindFramebuffer(GL_FRAMEBUFFER, intermediateFBO);
GLubyte* pixels = (GLubyte*)calloc(width*height*4,sizeof(GLubyte));
glReadPixels(0, 0,width, height,GL_RGBA, GL_UNSIGNED_BYTE, pixels);
writePNG(pixels);
It seems there're at least two errors in the code in the original question:
The framebuffer should have a multisample texture attached, not a renderbuffer (glFramebufferTexture2D(... GL_TEXTURE_2D_MULTISAMPLE instead of glRenderbufferStorageMultisample)
Must call glBindFramebuffer(GL_FRAMEBUFFER, intermediateFBO); after blitting and before glReadPixels
I have been looking for OpenGL Multi Sample Anti Aliasing tutorials and I found many but I'll take 2.
They use a different way to do this. I have tested both ways and both work for my project so I can use any of them.
I use this to render my game engine scene to a texture.
This is the 1st way:
Create the FBO with MSAA
// create a texture object
glGenTextures(1, &textureId);
glBindTexture(GL_TEXTURE_2D, textureId);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_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, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTexture(GL_TEXTURE_2D, 0);
// create a MSAA framebuffer object
// NOTE: All attachment images must have the same # of samples.
// Ohterwise, the framebuffer status will not be completed.
glGenFramebuffers(1, &fboMsaaId);
glBindFramebuffer(GL_FRAMEBUFFER, fboMsaaId);
// create a MSAA renderbuffer object to store color info
glGenRenderbuffers(1, &rboColorId);
glBindRenderbuffer(GL_RENDERBUFFER, rboColorId);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, MSAA_level, GL_RGB8, width, height);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
// create a MSAA renderbuffer object to store depth info
// NOTE: A depth renderable image should be attached the FBO for depth test.
// If we don't attach a depth renderable image to the FBO, then
// the rendering output will be corrupted because of missing depth test.
// If you also need stencil test for your rendering, then you must
// attach additional image to the stencil attachement point, too.
glGenRenderbuffers(1, &rboDepthId);
glBindRenderbuffer(GL_RENDERBUFFER, rboDepthId);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, MSAA_level, GL_DEPTH_COMPONENT, width, height);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
// attach msaa RBOs to FBO attachment points
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, rboColorId);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepthId);
// create a normal (no MSAA) FBO to hold a render-to-texture
glGenFramebuffers(1, &fboId);
glBindFramebuffer(GL_FRAMEBUFFER, fboId);
glGenRenderbuffers(1, &rboId);
glBindRenderbuffer(GL_RENDERBUFFER, rboId);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
// attach a texture to FBO color attachement point
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureId, 0);
// attach a rbo to FBO depth attachement point
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboId);
//## disable color buffer if you don't attach any color buffer image,
//## for example, rendering the depth buffer only to a texture.
//## Otherwise, glCheckFramebufferStatus will not be complete.
//glDrawBuffer(GL_NONE);
//glReadBuffer(GL_NONE);
// check FBO status
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
return false;
glBindFramebuffer(GL_FRAMEBUFFER, 0);
And when I need to draw the scene
glBindFramebuffer(GL_FRAMEBUFFER, fboMsaaId);
glViewport(0, 0, width, height);
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
DrawScene();
glBindFramebuffer(GL_READ_FRAMEBUFFER, fboMsaaId);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fboId);
glBlitFramebuffer(0, 0, width, height, // src rect
0, 0, width, height, // dst rect
GL_COLOR_BUFFER_BIT, // buffer mask
GL_LINEAR); // scale filter
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0, 0, App->window->GetWidth(), App->window->GetHeight());
The 2nd way:
Create the FBO with MSAA
unsigned int framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
// create a multisampled color attachment texture
unsigned int textureColorBufferMultiSampled;
glGenTextures(1, &textureColorBufferMultiSampled);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, textureColorBufferMultiSampled);
glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB, SCR_WIDTH, SCR_HEIGHT, GL_TRUE);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, textureColorBufferMultiSampled, 0);
// create a (also multisampled) renderbuffer object for depth and stencil attachments
unsigned int rbo;
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8, SCR_WIDTH, SCR_HEIGHT);
glBindRenderbuffer(GL_RENDERBUFFER, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << endl;
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// configure second post-processing framebuffer
unsigned int intermediateFBO;
glGenFramebuffers(1, &intermediateFBO);
glBindFramebuffer(GL_FRAMEBUFFER, intermediateFBO);
// create a color attachment texture
unsigned int screenTexture;
glGenTextures(1, &screenTexture);
glBindTexture(GL_TEXTURE_2D, screenTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, screenTexture, 0); // we only need a color buffer
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
cout << "ERROR::FRAMEBUFFER:: Intermediate framebuffer is not complete!" << endl;
glBindFramebuffer(GL_FRAMEBUFFER, 0);
And when I need to draw the scene:
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glViewport(0, 0, width, height);
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
DrawScene();
glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, intermediateFBO);
glBlitFramebuffer(0, 0, SCR_WIDTH, SCR_HEIGHT, 0, 0, SCR_WIDTH, SCR_HEIGHT, GL_COLOR_BUFFER_BIT, GL_LINEAR);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0, 0, App->window->GetWidth(), App->window->GetHeight());
Summarizing:
1st way: Create FBO, create RBO for color and RBO for depth and use glRenderbufferStorageMultisample(...) to specify the MSAA level. Then create other FBO with texture for color and RBO for depth.
2nd way: Create FBO, create Texture for color and RBO for depth and using glTexImage2DMultisample(...) for MSAA level in the texture. Then create other FBO and a texture.
What are the differences on using one way or other? Is one better than the other?
MSAA setup in your example is actually the same in both cases. The only difference between the two methods you depicted is - different FBO attachment type. In general, you will want to attach a texture and not render buffer when you later need to use the information from that FBO for further render passes. In such a case you would plug previous render pass FBO's texture attachment into texture unit, and sample from it in the next pass shader program. Shadow mapping is one of such cases.
At the moment I'm playing with FBO, which I don't really master. I have no problems with color atachments, but I can't figure out how to use depth textures in my render.
At the moment, I render my scene on a FBO (color+depth), then I draw a textured quad using the depth texture... But it doesn't work, my screen stays black (everyhting is 0 : even if i multiply by 1000 it stays at 0). (Depth test works : if I render the color texture instead of the depth, depth test works correctly)
Rendering loop :
///Render to FBO
glEnable(GL_DEPTH_TEST);
FBO.Bind(); //Do I really need to explain what it does ?
glUseProgram(ShaderProgram->getProgramID());
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
///Setting uniforms etc
mainScene.drawAll();
//draw the quad
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glClear(GL_COLOR_BUFFER_BIT);
glDisable(GL_DEPTH_TEST);
glViewport(0, 0, m_window.getSize().x, m_window.getSize().y);
glUseProgram(2DShader.getProgramID());
quadModel.bindVAO();
glBindTexture(GL_TEXTURE_2D, FBO.DepthTexureID);
glDrawArrays(GL_TRIANGLES, 0, 6);
And FBO creation :
glGenFramebuffers(1, &FBO_ID);
glBindFramebuffer(GL_FRAMEBUFFER, FBO_ID);
glGenTextures(1, &ColorBufferID);
glBindTexture(GL_TEXTURE_2D, ColorBufferID);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ColorBufferID, 0);
glBindTexture(GL_TEXTURE_2D, 0);
glGenTextures(1, &DepthTexture);
glBindTexture(GL_TEXTURE_2D, DepthTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, width, height, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, DepthTexture, 0);
glBindTexture(GL_TEXTURE_2D, 0);
Any idea ?
Your depth texture is not mipmap-complete, but you are using the default mipmap filtering, so sampling will fail. Just specify some non-mipmapping filters like GL_NEAREST or LINEAR for sampling that texture.
I am trying to get into screen a video frame in a 2d texture covering the screen, I must use framebuffers, because eventually I wish to do the ping-pong rendering technique. But for the time being I want first to achieve just to render on the screen by using framebuffers.
This is my setup code:
// Texture setup
int[] text = new int[1];
glGenTextures(1, text, 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, text[0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 512, 512, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, null);
// Frambuffer setup
int[] fbo = new int[1];
glGenFramebuffers(1, fbo, 0);
glBindFramebuffer(GL_FRAMEBUFFER, fbo[0]);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, text[0], 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
Till here all ok, I didn't write here the testing code to keep it small, but right after I check if the frame buffer was created correctly, and all is fine.
Now in my Render loop I do next:
// Use the GLSL program
glUseProgram(programHandle);
// Swap to my FBO
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebuffer(GL_FRAMEBUFFER, fbo[0]);
glViewport(0, 0, 512, 512);
// Pass the new image data to the program so the fragment shader processes it.
// Using glTexSubImage2D to speed up
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, text[0]);
glUniform1i(glGetUniformLocation(programHandle, "u_texture"), 0);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 512, 512, GL_LUMINANCE, GL_UNSIGNED_BYTE, NewImageData);
// Draw the quad
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
// Swap back to the default screen frambuffer
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glBindTexture(GL_TEXTURE_2D, 0);
At this point I get a black screen, and on the log I can see a GL_INVALID_FRAMEBUFFER_OPERATION 1286.
I tried putting the glDrawArrays after the glBindFramebuffer call, but then the application crashes.
Any thoughts? Thanks in advance.
LUMINANCE textures are not renderable, this means you can't render to them using a FBO. This problem is solved with the GL_ARB_texture_rg extension, which introduces one and two channel texture formats that are renderable.