playcanvas/build/playcanvas/src/scene/shader-lib/chunks/lit/frag/TBNderivative.js

PlayCanvas WebGL game engine

var TBNderivativePS = "\nuniform float tbnBasis;\nvoid getTBN(vec3 tangent, vec3 binormal, vec3 normal) {\n	vec2 uv = $UV;\n	vec3 dp1 = dFdx( vPositionW );\n	vec3 dp2 = dFdy( vPositionW );\n	vec2 duv1 = dFdx( uv );\n	vec2 duv2 = dFdy( uv );\n	vec3 dp2perp = cross( dp2, normal );\n	vec3 dp1perp = cross( normal, dp1 );\n	vec3 T = dp2perp * duv1.x + dp1perp * duv2.x;\n	vec3 B = dp2perp * duv1.y + dp1perp * duv2.y;\n	float denom = max( dot(T,T), dot(B,B) );\n	float invmax = (denom == 0.0) ? 0.0 : tbnBasis / sqrt( denom );\n	dTBN = mat3(T * invmax, -B * invmax, normal );\n}\n";

export { TBNderivativePS as default };