What does TextureImporter "lightmap" checkbox?

Questions & Answers
1

I have a texture in my assets, it has the “lightmap” checkbox marked in the texture importer. I use it to replace a scene lightmap with the following command:

LightmapData[] lightmaps = LightmapSettings.lightmaps;
lightmaps[0].lightmapFar = myAsset;
LightmapSettings.lightmaps = lightmaps;

It works fine.
If I uncheck it the lightmap checkbox it also works, but get to bright (that’s ok).

Now, I’m trying to clone it (cause I need to manipulate the copy) and apply the clone to the lightmap using the following code:

Texture2D newOne = new Texture2D(myAsset.width, myAsset.height, myAsset.format,  true);
newOne.filterMode = myAsset.filterMode;
newOne.anisoLevel = myAsset.anisoLevel;
newOne.wrapMode = myAsset.wrapMode;
newOne.mipMapBias = myAsset.mipMapBias;
newOne.hideFlags = myAsset.hideFlags;
newOne.SetPixels(result);
newOne.Apply();

But when I use this new generated texture as lightmap as I did with the asset it gets too bright, just like happened with the asset without the “lightmap” checked.

So my question is: What does Texture importer “lightmap” checkbox and how can I simulate it on the generated texture?

2

WHat I do is copy the lightmap texture to a new texture, using something similar to what you do. Then I encode it as a PNG and write it to file. Then since this is an ordinary PNG Unity imports it as normal which means we get a texture importer that we can set the lightmap property on. Another thing to note, because the lightmap looks like its encoded between 0 and 0.5 you will need to loop through each texel and double the value.

Something like:

	Texture2D texture = LightmapSettings.lightmaps[lightmapIndex].lightmapFar;

	// Do lightmap changes here to texture

	texture.Apply();

	Texture2D newTexture = new Texture2D(texture.width, texture.height,texture.format, true);
	
	for (int x = 0; x < texture.width; x++)
	{
		for (int y = 0; y < texture.height; y++)
		{
			Color newColor = texture.GetPixel(x,y);
			newColor = new Color(newColor.r * 2, newColor.g * 2,  newColor.b * 2, newColor.a * 2);
			newTexture.SetPixel(x,y,newColor);
		}
	}
	string path = AssetDatabase.GetAssetPath(texture);
	string extension = Path.GetExtension(path);
	path = path.Remove(path.Length - extension.Length);
	path += ".png";
	
	
	byte[] bytes = newTexture.EncodeToPNG();
	string fullpath = Application.dataPath + "/../" + path;
	File.WriteAllBytes(fullpath, bytes);