Softimage XSI is another program like Blender, Maya, Max, etc. It’s very high-end and very expensive.
TODO means “to do”, as in “things yet to be done”. Often paired with ‘list’ as in “to do list”. Sorry about that.
Graphics cards have special hardware that increases speed in the following ways:
[>] The 3D data need only be sent to the video memory once, instead of every frame of the animation. Moving data from the host memory to video memory is still a fairly slow process (though not nearly as slow as it used to be). What this means is that the GPU (your video card’s CPU) can work on its own data without having to wait for it from the host CPU. The only thing it needs are a few small pieces of data here and there to instruct it what to do with its data (camera angle, etc.)
[>] Optimized cheats. When you load data to the GPU, you are required to do so in a specific way: typically as an array of faces, each of which is a collection of 3D spatial points and 2D UV-coordinates. The ability to map an image to a face is very highly optimized for speed. It is also very easy to do simple shading tricks (shadows, directional light sources, etc.) which when done right (as the GPU is programmed to do) produces some very impressive results.
[>] Hardwired code. The GPU only performs specific tasks as a slave processor. Thus, it doesn’t need all the overhead the host CPU does to load, decode, and execute multipurpose instructions. While some GPU’s have a limited ability to be programmed, it is far from the power and flexibility obtainable from a general purpose CPU.
So, removing all the general purpose overhead and doing a small number of things well and fast, the GPU has a speed advantage when performing graphic bitblt, shading, lighting, etc. operations.
The thing you should note is that it is all an illusion. The GPU does not raytrace a scene. If it did it’d take about as long as the CPU. The GPU cheats, and does it well.
The point of raytracing is the ‘accurate’ modelling of light in 3D space. The accuracy will of course depend upon the type of raytracer… but it is still far more capable than the GPU’s bag of tricks.
For example, try to model a fishbowl in bright sunlight and all the prismatic effects that come out of it. The GPU just can’t do it. It has to cheat to approximate the effect.
So the point is that 3D modellers and 3D game modellers have different goals. The latter is to make the game look pretty. The former is physical accuracy.
I hope this helps clear things.
hmm… it looks like [b]joostbouwer[/ib] beat me to the punch…