Next: Bibliography Up: Single Sample Soft Shadows Previous: Results

# Appendix: Example occluders

For a shadow ray toward a light with position and diameter D, and a sphere with center and radius R, we need to decide whether we are in the penumbra region, and if so, what is the value of , the fractional distance between umbra and penumbra boundaries. We first compute the distance t0 to the point on the shadow ray closest to : . If t0 is negative, then s=1. We then compute b by assuming , , so we use

We compute the value of the minimum distance d from to the ray:

If this distance is between R and R+b then we compute and then compute . If d < R, s = 0, and if d > R+b, s = 1. The radius of the bounding volume for the sphere for shadow ray testing is R + bmax where bmax is a function of the largest light and cannot be larger than Dmax.

For triangles, the outer object is a triangle with rounded corners. The offset is different for each side of the triangle and is proportional to the cosine of projected triangle normal and the vector .

Next: Bibliography Up: Single Sample Soft Shadows Previous: Results