display.per_pixel_lighting (off by default) lights the models for each
pixel by the same ambient, distant and point lights the model lighting
programs (9, 10, 17 and 27) sum for each vertex. The normal and position
are found in each program's instructions and the program is checked to
light as the pixel shader does; the lights come in a small uniform of
their own, and a shader that fails falls back to per-vertex lighting.
Based on #48 by Tyberious.
MrBruh
3dba558e4f