Render to 3D Texture with OpenGL on OSX (multi-layer framebuffer attachment)

Question

I have an OpenGL 3.2 CORE context on OSX 10.7.5 set up and trying to render to a 3D texture, using a layered rendering approach. The geometry shader feature "gl_layer" is supported, but I cannot bind a GL_TEXTURE_3D to my framebuffer attachment. It returns GL_FRAMEBUFFER_UNSUPPORTED.

This is the card and driver version in my MBP:

AMD Radeon HD 6770M 1024 MB - OpenGL 3.2 CORE (ATI-7.32.12)

This feature does not directly relate to a specific extension AFAIK. Does anybody know how to figure out whether this is unsupported by the driver or hardware? Thanks so much.

Below the code to reconstruct. I use glfw to set up the context:

// Initialize GLFW
if (!glfwInit())
    throw "Failed to initialize GLFW";

glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

// Open a window and create its OpenGL context
if (!glfwOpenWindow(720, 480, 8, 8, 8, 8, 24, 8, GLFW_WINDOW))
    throw "Failed to open GLFW window";

//
// ...
//

GLuint framebuffer, texture;
GLenum status;
glGenFramebuffers(1, &framebuffer);
// Set up the FBO with one texture attachment
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffer);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_3D, texture);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, 256, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glFramebufferTexture(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture, 0);
status = glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER);
if (status != GL_FRAMEBUFFER_COMPLETE)
    throw status;
//
// status is GL_FRAMEBUFFER_UNSUPPORTED here !!!
//

glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
glDeleteTextures(1, &texture);
glDeleteFramebuffers(1, &framebuffer);
exit(1);

Answer 1

Does anybody know how to figure out whether this is unsupported by the driver or hardware?

It just told you. That's what GL_FRAMEBUFFER_UNSUPPORTED means: it's the driver exercising veto-power over any framebuffer attachments it doesn't like for any reason whatsoever.

There's not much you can do when this happens except to try other things. Perhaps rendering to a 2D array texture.