I am attempting to render to a texture in ios with multisampling enabled and then use that texture in my final output. Is this possible?
So far I have only gotten black textures or aliased images. The code I am using is:
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA4, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenRenderbuffers(1, &colorRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
//glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8_OES, width, height);
glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 4, GL_RGBA4, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
glGenRenderbuffers(1, &depthRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
//glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, width, self.view.bounds.size.height);
glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 4, GL_DEPTH_COMPONENT16, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER) ;
if(status != GL_FRAMEBUFFER_COMPLETE) {
NSLog(@"failed to make complete framebuffer object %x", status);
}
// Render my scene
glBindFramebuffer( GL_FRAMEBUFFER, framebuffer );
glViewport(0,0,width,height);
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
// Draw scene
// Then bind default framebuffer
glBindFramebuffer( GL_FRAMEBUFFER, 1 );
// Draw other things
// Now resolve the multisampling and draw texture
glResolveMultisampleFramebufferAPPLE();
glUseTexture( GL_TEXTURE_2D, texture );
// Draw with texture
This code does not work. It fails if I make the depth render buffer multisampled. If I just use a normal fbo for the depth then it works, but produces an aliased image.
Anyone know where I am going wrong?
Thanks!
Yes! I found what I was doing wrong. I wrongly thought that I could have the following:
Framebuffer
But you cannot do this. D: You have to have the following:
Multisampled framebuffer:
Normal framebuffer:
I.e. you have to copy the results of the multisampled render to a whole new framebuffer.
Some code:
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA4, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
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);
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenRenderbuffers(1, &colorRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 4, GL_RGBA8_OES, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
glGenRenderbuffers(1, &depthRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 4, GL_DEPTH_COMPONENT16, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER) ;
if(status != GL_FRAMEBUFFER_COMPLETE) {
NSLog(@"failed to make complete framebuffer object %x", status);
}
// Render my scene
glBindFramebuffer( GL_FRAMEBUFFER, framebuffer );
glViewport(0,0,width,height);
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
// Draw scene
// Then bind default framebuffer
glBindFramebuffer( GL_FRAMEBUFFER, 1 );
// Draw other things
// Now resolve the multisampling into the other fbo
glBindFramebuffer( GL_READ_FRAMEBUFFER_APPLE, framebuffer );
glBindFramebuffer( GL_DRAW_FRAMEBUFFER_APPLE, resolved_framebuffer );
glResolveMultisampleFramebufferAPPLE();
glBindTexture( GL_TEXTURE_2D, texture );
// Draw with texture
Thanks Goz, you got me in the right direction!
I assume you've been working from the sample on this page?
Remove the glFramebufferTexture2D call as this may be causing the multisample render buffer to detach and hence you are have a multisampled back buffer and a single sampled render buffer. Furthermore, creating a single sampled depth buffer wil solve your issues as it will not be paired with theat single sampled render buffer.
Edit: When do you get the error? On the one creating the render buffer? If so you may be best off trying it exactly as in the link I posted (which I assume you are working for).
ie.
glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 4, GL_RGBA8_OES, width, height);