@google/model-viewer
Version:
Easily display interactive 3D models on the web and in AR!
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text/typescript
/**
* @license MIT
* @see https://github.com/mrdoob/three.js/blob/dev/LICENSE
*/
export const normalmapChunk = /* glsl */ `
uniform sampler2D normalMap;
uniform vec2 normalScale;
uniform mat3 normalMatrix;
// Per-Pixel Tangent Space Normal Mapping
// http://hacksoflife.blogspot.ch/2009/11/per-pixel-tangent-space-normal-mapping.html
vec3 perturbNormal2Arb( vec3 eye_pos, vec3 surf_norm, vec2 normalScale, in sampler2D normalMap ) {
// Workaround for Adreno 3XX dFd*( vec3 ) bug. See #9988
vec3 q0 = vec3( dFdx( eye_pos.x ), dFdx( eye_pos.y ), dFdx( eye_pos.z ) );
vec3 q1 = vec3( dFdy( eye_pos.x ), dFdy( eye_pos.y ), dFdy( eye_pos.z ) );
vec2 st0 = dFdx( vUv.st );
vec2 st1 = dFdy( vUv.st );
float scale = sign( st1.t * st0.s - st0.t * st1.s ); // we do not care about the magnitude
vec3 S = normalize( ( q0 * st1.t - q1 * st0.t ) * scale );
vec3 T = normalize( ( - q0 * st1.s + q1 * st0.s ) * scale );
vec3 N = normalize( surf_norm );
// (elalish) Biased the normal mip to anti-alias the normal's screen-space derivatives
vec3 mapN = texture2D( normalMap, vUv, 2.0 ).xyz * 2.0 - 1.0;
mapN.xy *= normalScale;
// Workaround for Adreno GPUs gl_FrontFacing bug. See #15850 and #10331
// http://hacksoflife.blogspot.com/2009/11/per-pixel-tangent-space-normal-mapping.html?showComment=1522254677437#c5087545147696715943
vec3 NfromST = cross( S, T );
if( dot( NfromST, N ) > 0.0 ) {
S *= -1.0;
T *= -1.0;
}
mapN.xy *= ( float( gl_FrontFacing ) * 2.0 - 1.0 );
mat3 tsn = mat3( S, T, N );
return normalize( tsn * mapN );
}
`;