Normals and refraction
Posted: Wed Jun 06, 2018 1:04 pm
I achieved promising results with lenses made of quite fine meshes, and normals interpolated from face normals. Now I want to optimize precision and performance. I need validate my understanding of normals.
My understanding is that (with BIDIRCPU) luxcore takes the normals to bend/curve faces to calculate the ray-face crossing points and angle for refraction. This smoothes the approximation of concav/convex surfaces by meshes. Is this correct?
Lets take it to the extreme with the following vertices, connect each three neighbors to 8 faces, and copy the vertices as normals.
-1 0 0
0 -1 0
0 0 -1
1 0 0
The results would still have the geometry of a cube, appears as a cube, has the shadow of a cube. But the color is smoothly shaded leaving no edges visible in the shading.
And the refraction should actually be like from a perfect sphere.
So it produces the refraction from a sphere but the shadow of a cube???
Here rendered without normals vs. with normals:
My understanding is that (with BIDIRCPU) luxcore takes the normals to bend/curve faces to calculate the ray-face crossing points and angle for refraction. This smoothes the approximation of concav/convex surfaces by meshes. Is this correct?
Lets take it to the extreme with the following vertices, connect each three neighbors to 8 faces, and copy the vertices as normals.
-1 0 0
0 -1 0
0 0 -1
1 0 0
The results would still have the geometry of a cube, appears as a cube, has the shadow of a cube. But the color is smoothly shaded leaving no edges visible in the shading.
And the refraction should actually be like from a perfect sphere.
So it produces the refraction from a sphere but the shadow of a cube???
Here rendered without normals vs. with normals: