fireball/lib/renderers/shaders/ShaderChunk/bumpmap_pars_fragment.glsl
2018-12-25 17:29:22 +03:30

45 lines
1.3 KiB
GLSL

#ifdef USE_BUMPMAP
uniform sampler2D bumpMap;
uniform float bumpScale;
// Bump Mapping Unparametrized Surfaces on the GPU by Morten S. Mikkelsen
// http://api.unrealengine.com/attachments/Engine/Rendering/LightingAndShadows/BumpMappingWithoutTangentSpace/mm_sfgrad_bump.pdf
// Evaluate the derivative of the height w.r.t. screen-space using forward differencing (listing 2)
vec2 dHdxy_fwd() {
vec2 dSTdx = dFdx( vUv );
vec2 dSTdy = dFdy( vUv );
float Hll = bumpScale * texture2D( bumpMap, vUv ).x;
float dBx = bumpScale * texture2D( bumpMap, vUv + dSTdx ).x - Hll;
float dBy = bumpScale * texture2D( bumpMap, vUv + dSTdy ).x - Hll;
return vec2( dBx, dBy );
}
vec3 perturbNormalArb( vec3 surf_pos, vec3 surf_norm, vec2 dHdxy ) {
// Workaround for Adreno 3XX dFd*( vec3 ) bug. See #9988
vec3 vSigmaX = vec3( dFdx( surf_pos.x ), dFdx( surf_pos.y ), dFdx( surf_pos.z ) );
vec3 vSigmaY = vec3( dFdy( surf_pos.x ), dFdy( surf_pos.y ), dFdy( surf_pos.z ) );
vec3 vN = surf_norm; // normalized
vec3 R1 = cross( vSigmaY, vN );
vec3 R2 = cross( vN, vSigmaX );
float fDet = dot( vSigmaX, R1 );
fDet *= ( float( gl_FrontFacing ) * 2.0 - 1.0 );
vec3 vGrad = sign( fDet ) * ( dHdxy.x * R1 + dHdxy.y * R2 );
return normalize( abs( fDet ) * surf_norm - vGrad );
}
#endif