I'm not sure what (l,r,t,b,n,f) means. Are they some sort of coordinates? Or the absolute distances?
motoole2
@Louise These are parameters that device the six sides of our view frustum.
Edit: Ok, that was a bit of a short explanation, so let me expand on this a bit. The OpenGL function glFrustum takes as input six parameters, specifying the location of all six faces of the view frustum: left, right, top, bottom, near, and far. In the background, OpenGL takes these parameters and forms a matrix to perform perspective projection (the same matrix shown here). This matrix transforms the eight vertices of the view frustum, x_k for k=1 to 8 (see left image), to vertices representing the corners of a cube. Any point contained within this view frustum will map to a 3D vertex with coordinate values between -1 and 1, i.e., points within the cube.
I'm not sure what (l,r,t,b,n,f) means. Are they some sort of coordinates? Or the absolute distances?
@Louise These are parameters that device the six sides of our view frustum.
Edit: Ok, that was a bit of a short explanation, so let me expand on this a bit. The OpenGL function glFrustum takes as input six parameters, specifying the location of all six faces of the view frustum: left, right, top, bottom, near, and far. In the background, OpenGL takes these parameters and forms a matrix to perform perspective projection (the same matrix shown here). This matrix transforms the eight vertices of the view frustum,
x_kfork=1to8(see left image), to vertices representing the corners of a cube. Any point contained within this view frustum will map to a 3D vertex with coordinate values between -1 and 1, i.e., points within the cube.