Get the maximum scale in lightmap for any renderer!

Unity Engine
1

Hey,

I’m trying to create an editor script to set the ‘scale in lightmap’ value to its maximum for any selected game object with a mesh renderer on it. So as a result each object that I do this to, will get a full light map allocated only for that particular object. I have noticed in the editor that, if we increase the scale above the max possible scale, it shows a warning that says ‘Object’s size in lightmap has reached the max atlas size’. Is there a way to see how they are actually calculating that limit in the mesh renderer component?? . I have tried pretty much everything else I can think of. If anyone is interested I can post my half done solution.

Thanks

3152653--239662--Capture.PNG

2

Bumping this question. Any have any ideas??

3

Bumping, this should really be a thing

4

Hi,

The number of texels (light pixels) of a renderer must be lower than the number of texels in a single lightmap.

Capture2

Number of texels in a single lightmap: Max Lightmap Size * Max Lightmap Size = 1024 * 1024

In the simple case of a basic cube like the following:

Capture.PNG
Capture.PNG1702×587 144 KB

Number of texels for (the area of) a cube (length of side: 1 unit): Scale X * Scale Y * 2 + Scale X * Scale Z * 2 + Scale Y * Scale Z * 2 * Lightmap Resolution = ((1600 * 1300 * 2) + (1600 * 1000 * 2) + (1300 * 1000 * 2)) * 1

Number of texels for (the area of) a cube < Number of texels in a single lightmap

The “Scale In Lightmap” parameter allows to respect that constraint and it seems to be squared, so that the constraints becomes:

Number of texels for (the area of) a cube * (Scale In Lightmap*Scale In Lightmap) < Number of texels in a single lightmap

In the example above:

Scale In Lightmap < sqrt(1024 * 1024 / ((1600 * 1300 * 2) + (1600 * 1000 * 2) + (1300 * 1000 * 2))) = 0.3245

In case a custom mesh, the area seems to be calculated/evaluated by Unity but I didn’t invest much. I guess we can discover more by looking at the sources: UnityCsReference/Editor/Mono/Inspector/RendererLightingSettings.cs at master · Unity-Technologies/UnityCsReference · GitHub