How to downsample a texture?

How can I downsample a texture using FBOs?

• I am rendering a scene to FBO as my render target whose size is 8 times the size of the orignal screen in OpenGL. Now i wan to downsample the texture generated by FBO to the size of the screen so as to achieve spatial anti aliasing. How do i achieve the down sampling ? Please provide implementation details. Note : If there is a better way of doing anti aliasing in FBOs please mention that too. I am trying to remove the aliasing in the image attached below.

• Answer:

  Since your render target is exactly 8 times the size of the screen, I'd just use glGenerateMipmap, after setting glTexParameteri(..., GL_TEXTURE_MAX_LEVEL, 3);. Then, just blit or whatever from mipmap level 3, and you're done. But really, you're wasting a lot of performance by not using multisampling+aniso. Supersampling won't give you much that you won't get with multisampling and anisotropic filtering, and your rendering will be that much faster for it.