A lot of over-zealous PHD students have come up with papers describing soft shadowing techniques, but in reality, most of these techniques are not viable in real-time, at least when considering complex scenes. Hence, we need to fake soft shadows in order to improve the visual quality of the scene. Hard shadows destroy the realism of a scene. But there are solutions to this and since the advantages outweigh the disadvantages, this will be the technique of my choice in this article. Though this technique has several advantages, it suffers from aliasing artifacts and z-fighting. Shadow mapping on the other hand is an image space technique that involves rendering the scene depth from the light's point of view and using this depth information to determine which portions of the scene in shadow. Because of this, shadow mapping is slowly becoming more popular.

Two major problems with this technique are that it is heavily geometry dependent and fill-rate intensive. This technique is pixel-accurate and doesn't suffer from any aliasing problems, but as with any technique, it suffers from its share of disadvantages. Then, via ray casting, the shadowed portions of the scene can be determined (usually the stencil buffer is used to simulate ray-casting). The shadow volumes technique is a geometry based technique that requires the extrusion of the geometry in the direction of the light to generate a closed volume. Two popular dynamic shadowing techniques are shadow volumes and shadow mapping. But with the advent of powerful programmable graphics hardware, dynamic shadow techniques have nearly completely replaced static techniques like light mapping and semi-dynamic techniques like projected shadows. Originally, dynamic shadowing techniques were possible only in a limited way.

Soft shadows in cheetah3d