Volume Shaders

1
Volume Shaders

• Now you see them, now you dont

2
Volume Shader Paradigm
Light
Eye
I
P
Regular Geometry (surface shaders)
3
Volume Shader Paradigm
Volume Shader
Light
Eye
I
P
Regular Geometry (surface shaders)
4
Simple Volume Shader
volume fog ( float distance 1 color
background color(.5,.5,.5)) float d 1
exp(-length(I)/distance) Ci mix(Ci,
background, d) Oi mix(Oi, color(1,1,1),
d)
5
Ray Marching

• Step along the ray starting at the eye
• At each step calculate the density of the
  volume and anything else that might attenuate
  the original color and opacity returned by
  incident ray, I

6
Ray Marching
Volume Shader
Light
Eye
I
P
Regular Geometry (surface shaders)
7
Ray Marching

• Step along the ray starting at the eye
• At each step calculate the density of the
  volume and anything else that might attenuate
  the original color and opacity return by incident
  ray I
• Taking the values calculated attenuate Ci and Oi