Comments on: Better Sampling

By: ShinZo

ShinZo — Fri, 04 Jun 2010 22:50:42 +0000

You should change:

return Vector3(x, y, Sqrt(Max(0.0f, 1 – x * x – y * y)));

return Vector3(x, y, Sqrt(Max(0.0f, 1 – u1)));

because (x * x – y * y) = u1 in your example

By: rory

rory — Thu, 11 Jun 2009 16:16:50 +0000

This function just generates the ray direction in tangent space. It assumes that you will rotate the direction into world space afterwards.

I just use the normal and tangent vectors from the mesh (generating the bitangent from the cross product) and generate a basis (3×3 matrix) which transforms the ray from tangent space into world space.

By: Freeman

Freeman — Thu, 11 Jun 2009 08:03:35 +0000

Hi,

Nice article

I just have a question about the randomly generated point on the hemisphere.
In your code, you never use the normal to generate it. How do you know that the hemisphere is centered on the normal ?