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

PlayCanvas WebGL game engine

var TBNPS = `
#ifdef LIT_TANGENTS
	#define TBN_TANGENTS
#else
	#if defined(LIT_USE_NORMALS) || defined(LIT_USE_CLEARCOAT_NORMALS)
		#define TBN_DERIVATIVES
	#endif
#endif
#if defined(TBN_DERIVATIVES)
	uniform float tbnBasis;
#endif
void getTBN(vec3 tangent, vec3 binormal, vec3 normal) {
	#ifdef TBN_TANGENTS
		dTBN = mat3(normalize(tangent), normalize(binormal), normalize(normal));
	#elif defined(TBN_DERIVATIVES)
		vec2 uv = {lightingUv};
		vec3 dp1 = dFdx( vPositionW );
		vec3 dp2 = dFdy( vPositionW );
		vec2 duv1 = dFdx( uv );
		vec2 duv2 = dFdy( uv );
		vec3 dp2perp = cross( dp2, normal );
		vec3 dp1perp = cross( normal, dp1 );
		vec3 T = dp2perp * duv1.x + dp1perp * duv2.x;
		vec3 B = dp2perp * duv1.y + dp1perp * duv2.y;
		float denom = max( dot(T,T), dot(B,B) );
		float invmax = (denom == 0.0) ? 0.0 : tbnBasis / sqrt( denom );
		dTBN = mat3(T * invmax, -B * invmax, normal );
	#else
		vec3 B = cross(normal, vObjectSpaceUpW);
		vec3 T = cross(normal, B);
		if (dot(B,B)==0.0)
		{
			float major=max(max(normal.x, normal.y), normal.z);
			if (normal.x == major)
			{
				B = cross(normal, vec3(0,1,0));
				T = cross(normal, B);
			}
			else if (normal.y == major)
			{
				B = cross(normal, vec3(0,0,1));
				T = cross(normal, B);
			}
			else if (normal.z == major)
			{
				B = cross(normal, vec3(1,0,0));
				T = cross(normal, B);
			}
		}
		dTBN = mat3(normalize(T), normalize(B), normalize(normal));
	#endif
}
`;

export { TBNPS as default };