three
Version:
JavaScript 3D library
44 lines (27 loc) • 971 B
JavaScript
export default /* glsl */`
uniform sampler2D normalMap;
uniform vec2 normalScale;
uniform mat3 normalMatrix;
// Normal Mapping Without Precomputed Tangents
// http://www.thetenthplanet.de/archives/1180
mat3 getTangentFrame( vec3 eye_pos, vec3 surf_norm, vec2 uv ) {
vec3 q0 = dFdx( eye_pos.xyz );
vec3 q1 = dFdy( eye_pos.xyz );
vec2 st0 = dFdx( uv.st );
vec2 st1 = dFdy( uv.st );
vec3 N = surf_norm; // normalized
vec3 q1perp = cross( q1, N );
vec3 q0perp = cross( N, q0 );
vec3 T = q1perp * st0.x + q0perp * st1.x;
vec3 B = q1perp * st0.y + q0perp * st1.y;
float det = max( dot( T, T ), dot( B, B ) );
float scale = ( det == 0.0 ) ? 0.0 : inversesqrt( det );
return mat3( T * scale, B * scale, N );
}
`;