Depth/Stencil texture buffers do not work with EXT_framebuffer_object on Intel.

When setting up the depth/stencil buffer of an EXT framebuffer using a renderbuffer instead of a texture, this is valid on all GPUs:

glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, depthStencilWidth, depthStencilHeight);
...
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,   GL_RENDERBUFFER_EXT, depthStencilRenderbuffer);
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depthStencilRenderbuffer);

Using the same technique, only with a texture instead will not work on Intel:

glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, depthStencilWidth, depthStencilHeight, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
...
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,   GL_TEXTURE_2D, depthStencilTexture, 0);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_TEXTURE_2D, depthStencilTexture, 0);

The above works fine with NVIDIA and AMD, but will crash on Intel as soon as you try to draw anything to the framebuffer (including glClear). The real culprit with the above code is the stencil attachment. Simply not attaching a stencil buffer will work, but you'll be sacrificing stencil operations.

The engine works around this issue by introducing the notion of "write-only" depth/stencil buffers. These are just renderbuffers instead of textures. These write-only buffers offer the best compatibility, but sacrifices the ability to read the depth and stencil values.

When using ARB_framebuffer_object, a depth/stencil texture works fine on all platforms:

glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, depthStencilWidth, depthStencilHeight, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
...
glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, depthStencilTexture, 0);

The GL_DEPTH_STENCIL_ATTACHMENT attachment point is not available in EXT_framebuffer_object, so the way the engine does things is it does not allow depth/stencil textures when only EXT_framebuffer_object is available, but allow it when ARB_framebuffer_object is available.

In OpenGL 3.?+ you must use vertex array objects.

I forget the exact version, but you must use vertex arrays when using a core OpenGL 3+ profile. glVertexAttribPointer can only take an offset. You can setup a default VAO during initialization, but you must place vertex and index data into buffer objects before setting up the attribute offsets and drawing.