Hi, I’ve tried to make a small FBO application, which seems to work. However the rendering speeds I get doesn’t quite make much sense to me.
I render the (simple) scene from a different POV to a texture, then render this alternate view in a quad along with the scene from the original POV.
I can toggle between using the FBO or a PBuffer for rendering to the texture.
Now, if I don’t enable mipmapping, the FBO is about twice as fast as the PBuffer. But if I enable mipmapping the FBO is about 2/3 the speed of the PBuffer.
I use glGenerateMipmapEXT with the FBO and glCopyTexSubImage2D and GL_SGIS_generate_mipmap for the PBuffer.
Any ideas as to why this is so? I was at least expecting them to be about same in speed. Am I doing something wrong?
I’m using a 7800GT with 93.71 drivers, the FBO is rendered using a 32bit RGBA color texture, and a 24bit depth RBO.