Terrain Texture: ORM map not applied properly

[lukaspj]

There is some bad math in the calculation of the ORM map, only the first layer with ORM is applied properly:

// Composite Matinfo map 0
float3 matinfoCol0 = lerp(float3(1.0,1.0,0.0),ormMapArray.Sample(ormMapSampler, float3(IN.detCoord0.xy,detailIdStrengthParallax[0].x)).rgb, detailBlend0);
OUT.col2 = float4(0.0,matinfoCol0);

// Composite Matinfo map 1
float3 matinfoCol1 = ormMapArray.Sample(ormMapSampler, float3(IN.detCoord1.xy, detailIdStrengthParallax[1].x)).rgb*detailBlend1;
OUT.col2.gba += matinfoCol1;

Wouldn't that set it to (1,1,0) after the first composite map, and then when you add the second composite map, those would get above 1 since you add it?

[lukaspj]

I tried changing it to:

   // Composite Matinfo map 0
   OUT.col2 = float4(0.0, 1.0, 1.0, 0.0);
   float3 matinfoCol0 = lerp(OUT.col2.gba, ormConfigMapTex0.Sample(ormConfigMap0, IN.detCoord0.xy).rgb, detailBlend0);
   OUT.col2.gba = matinfoCol0;
   
   // Composite Matinfo map 1
   float3 matinfoCol1 = lerp(OUT.col2.gba, ormConfigMapTex1.Sample(ormConfigMap1, IN.detCoord1.xy).rgb, detailBlend1);
   OUT.col2.gba = matinfoCol1;

And it seems better:

But there is still several oddities around the ORM map.

For example, inverting the roughness is completely broken:

[lukaspj]

Fixed by #424