Cell-based lighting?

Graphics Shaders & Materials
1

I am currently playing around with a cell-based idea, and am a bit stumped on whether or not the lighting is possible.

Each “cell” is just a spot with given properties. It may be a wall, a floor, empty space, whatever. In addition, each empty cell can have a light value (with 0 being completely dark). Light affects nearby cells - all surrounding cells will have the current cell’s light value minus one (unless it’s already brighter). If there is a neighboring cell with a solid material in it, the texture facing a cell with light in it will be lit according to that value.

The cells are in 3D, but here is a brief 2D illustration of the idea:

 +---+---+---+---+---+---+
 | 0 | 0 | 1 | 0 | 0 | 0 |
 +---+---+---+---+---+---+
 | 0 | 1 | 2 | 1 | 0 | 0 |
 +---+---+---+---+---+---+
 | 1 | 2 | 3 | 2 | 1 | 0 |
 +---+---+---+---+---+---+
 | 0 | 1 | 2 | 1 | 0 | 0 |
 +---+---+---+---+---+---+
 | 0 | 0 | 1 | 0 | 0 | 0 |
 +---+---+---+---+---+---+

The “3” is the light source, cells to the immediate side of that are “2”, cells immediately to the side of those are “1”, etc.

Is this possible to do via shaders alone, or would I have to do some horrible sequence of separate meshes?

2

thats doable through shader but only if its 1 light source only per cell that affects it.

3

I guess I should have clarified - how would I go about doing something like this?

4

I’m assuming you got this idea from minecraft’s lighting, which is exactly how he does it I believe.

I would simply change the mesh’s color value to increasingly dark values.

5

Yeah, I realized that was a fairly easy way to do it after some more tinkering. I was over complicating the matter. :sweat_smile:

6

This is actually the approach being used for the dynamic GI in Cryengine3- they render the lights view of the scene as a reflective shadow map, then using VTF sort that information into a volume texture.

Unfortunately since Unity doesn’t support volume textures (and the API complexities of rendering into a volume texture), and has limited support of VTF, you aren’t given the option to do it in realtime. Still, you can do some really cool effects using that kind of approach-

If you go the route of SH-lightmapping (Essentially, storing multiple values in each cell that describe the amount of lighting from key angles), you can regenerate the light influences from an arbitrary number of lights in your scene, even with relatively sparse data (You shouldn’t, for instance, attempt to encode shadows using this kind of technique, but you can capture general gradients really well)