I played NFS undergrounds, and i got impressed for the graphics…i saw a demo from nvidia( i think) that renders a torus with real time env mapping, with 4 balls around it. In my pc, it runs at 30 fps (geforce2), and nfs, rendering a lot of things (cars, streets, buldings) did it at ±30fps too. Does it render all the 6 faces from the cube map (perhaps only 2 or 3 by frame) or is there another way to achieve that effect? thanx
I have found, through experimentation, that you really only need to update one face of the cube map per frame (maybe even less) to get the desired result - but without impacting performance any more than necessary. But it would depend on (a) your frame rate, (b) the amount of change in your scene and © the resolution of your cube map.
Same conclusions than rgpc. I’m upadting my cube maps once per frame in my racing game, and it works fine (and fast!). Also, rendering the scene to a face of the cube map should be faster than a normal scene render. The texture resolution is a lot smaller (i use 256x256), hence decreasing fillrate. You can also decrease the render quality (no need for dot3 bumpmapping, or a view distance of 2 kilometers anyway!).
You wanna see project gotham racing 2 on the xbox. Some lovely graphics tricks in there.