LightShaft_Mesh

Cull Off
ZWrite Off
Blend One One

// Project camera position onto cross section
float3 DIR_UP             = float3(0, 1, 0);
float  dotWithYAxis       = dot(cameraPositionOS, DIR_UP);
float3 projOnCrossSection = normalize(cameraPositionOS - (DIR_UP * dotWithYAxis));

// Dot product to fade the geometry at the edge of the cross section
float dotProd           = abs(dot(projOnCrossSection, input.normal));
output.overallIntensity = pow(dotProd, _FadingEdgePower) * _CurrLightShaftIntensity;

Ref