| Projection shadows |
- Simple to understand: project the object geometry onto a plane.
- Fast for one flat receiver such as a ground plane.
- Produces sharp shadows without needing a shadow-map texture.
- No shadow-map resolution problems.
|
- Works mainly for simple receiving surfaces, especially planes.
- Does not handle self-shadowing.
- Hard to extend to complex scenes with many receivers.
- The shadow is fake geometry, so it needs special depth/blending handling.
|
| Shadow mapping |
- Works for general geometry, not only flat planes.
- Supports self-shadowing.
- One light-space depth map can shadow many visible surfaces.
- Closer to the real question: can the light see this point?
|
- Requires an extra render pass from the light's point of view.
- Needs a texture, extra uniforms, and shadow lookup logic.
- Can have aliasing if the shadow map resolution is too low.
- Can suffer from shadow acne or peter-panning, requiring bias tuning.
|