Shadow Volumes without using the Stencil Buffer:
A well known algorithm for the dynamic generation of shadows is the shadow volume algorithm by Crow (1977). Actual implementations require the support of a hardware accelerated stencil buffer. Nevertheless, we have shown recently that this is not an absolute requirement. We have modified the algorithm of Crow, such that the shadow mask can be computed in the alpha or even in the screen buffer. With these modifications shadow volumes are now also available on elder graphix hardware like the 3dfx Voodoo 1, 2 and 3 accelerators (left and centre image) or on platforms that do not support a stencil buffer such as the Sony PS2. What is more, we have managed to widen the main bottle neck of shadow mask rasterization by computing the shadow mask at lower resolutions as the scene (right image). This leads to a significant speed up at higher screen resolutions (see paper for more information). A demo movie captured on a 3dfx Voodoo2 is available here.