Framebuffer Depth Texture
If we require the depth test when rendering to a texture, then the framebuffer will require a depth buffer. This functionality should be enabled before use.
Like the color buffer, the depth buffer is an ordinary texture. It must have the same width and height as the color buffer, and the format must be
The depth texture's parameters need not be identical to the color buffer's, but under most circumstances the reasonable defaults are the same.