Fog Shader Node Linear Fog mode goes negative?

Mr_TT · February 28, 2023, 11:48am

Hi Folks,

I had a look at the shader code generated by the NME fog shader Node.
I think the fog coefficient in the function CalcFogFactor becomes negative for distances greater then the fog end value.

fogCoeff=(fogEnd-fogDistance)/(fogEnd-fogStart);

Greetings
Tom

tanpopo · February 28, 2023, 12:00pm

github.com

BabylonJS/Babylon.js/blob/6ff156f6c85c41c04555b54c24e01d6d7bd77176/packages/dev/core/src/Shaders/ShadersInclude/fogFragmentDeclaration.fx#L34


      
          	}

          	else if (FOGMODE_EXP == vFogInfos.x)

          	{

          		fogCoeff = 1.0 / pow(E, fogDistance * fogDensity);

          	}

          	else if (FOGMODE_EXP2 == vFogInfos.x)

          	{

          		fogCoeff = 1.0 / pow(E, fogDistance * fogDistance * fogDensity * fogDensity);

          	}

          

          	return clamp(fogCoeff, 0.0, 1.0);

          }

          #endif

fogCoeff will be clamped to 0 if it is negative and it is correct when you have a distance over the fog end.

Mr_TT · February 28, 2023, 12:12pm

Yes you are right