three
Version:
JavaScript 3D library
215 lines (119 loc) • 4.13 kB
JavaScript
export default /* glsl */`
// These shader functions convert between the UV coordinates of a single face of
// a cubemap, the 0-5 integer index of a cube face, and the direction vector for
// sampling a textureCube (not generally normalized ).
float getFace( vec3 direction ) {
vec3 absDirection = abs( direction );
float face = - 1.0;
if ( absDirection.x > absDirection.z ) {
if ( absDirection.x > absDirection.y )
face = direction.x > 0.0 ? 0.0 : 3.0;
else
face = direction.y > 0.0 ? 1.0 : 4.0;
} else {
if ( absDirection.z > absDirection.y )
face = direction.z > 0.0 ? 2.0 : 5.0;
else
face = direction.y > 0.0 ? 1.0 : 4.0;
}
return face;
}
// RH coordinate system; PMREM face-indexing convention
vec2 getUV( vec3 direction, float face ) {
vec2 uv;
if ( face == 0.0 ) {
uv = vec2( direction.z, direction.y ) / abs( direction.x ); // pos x
} else if ( face == 1.0 ) {
uv = vec2( - direction.x, - direction.z ) / abs( direction.y ); // pos y
} else if ( face == 2.0 ) {
uv = vec2( - direction.x, direction.y ) / abs( direction.z ); // pos z
} else if ( face == 3.0 ) {
uv = vec2( - direction.z, direction.y ) / abs( direction.x ); // neg x
} else if ( face == 4.0 ) {
uv = vec2( - direction.x, direction.z ) / abs( direction.y ); // neg y
} else {
uv = vec2( direction.x, direction.y ) / abs( direction.z ); // neg z
}
return 0.5 * ( uv + 1.0 );
}
vec3 bilinearCubeUV( sampler2D envMap, vec3 direction, float mipInt ) {
float face = getFace( direction );
float filterInt = max( cubeUV_minMipLevel - mipInt, 0.0 );
mipInt = max( mipInt, cubeUV_minMipLevel );
float faceSize = exp2( mipInt );
float texelSize = 1.0 / ( 3.0 * cubeUV_maxTileSize );
vec2 uv = getUV( direction, face ) * ( faceSize - 1.0 );
vec2 f = fract( uv );
uv += 0.5 - f;
if ( face > 2.0 ) {
uv.y += faceSize;
face -= 3.0;
}
uv.x += face * faceSize;
if ( mipInt < cubeUV_maxMipLevel ) {
uv.y += 2.0 * cubeUV_maxTileSize;
}
uv.y += filterInt * 2.0 * cubeUV_minTileSize;
uv.x += 3.0 * max( 0.0, cubeUV_maxTileSize - 2.0 * faceSize );
uv *= texelSize;
vec3 tl = envMapTexelToLinear( texture2D( envMap, uv ) ).rgb;
uv.x += texelSize;
vec3 tr = envMapTexelToLinear( texture2D( envMap, uv ) ).rgb;
uv.y += texelSize;
vec3 br = envMapTexelToLinear( texture2D( envMap, uv ) ).rgb;
uv.x -= texelSize;
vec3 bl = envMapTexelToLinear( texture2D( envMap, uv ) ).rgb;
vec3 tm = mix( tl, tr, f.x );
vec3 bm = mix( bl, br, f.x );
return mix( tm, bm, f.y );
}
// These defines must match with PMREMGenerator
float roughnessToMip( float roughness ) {
float mip = 0.0;
if ( roughness >= r1 ) {
mip = ( r0 - roughness ) * ( m1 - m0 ) / ( r0 - r1 ) + m0;
} else if ( roughness >= r4 ) {
mip = ( r1 - roughness ) * ( m4 - m1 ) / ( r1 - r4 ) + m1;
} else if ( roughness >= r5 ) {
mip = ( r4 - roughness ) * ( m5 - m4 ) / ( r4 - r5 ) + m4;
} else if ( roughness >= r6 ) {
mip = ( r5 - roughness ) * ( m6 - m5 ) / ( r5 - r6 ) + m5;
} else {
mip = - 2.0 * log2( 1.16 * roughness ); // 1.16 = 1.79^0.25
}
return mip;
}
vec4 textureCubeUV( sampler2D envMap, vec3 sampleDir, float roughness ) {
float mip = clamp( roughnessToMip( roughness ), m0, cubeUV_maxMipLevel );
float mipF = fract( mip );
float mipInt = floor( mip );
vec3 color0 = bilinearCubeUV( envMap, sampleDir, mipInt );
if ( mipF == 0.0 ) {
return vec4( color0, 1.0 );
} else {
vec3 color1 = bilinearCubeUV( envMap, sampleDir, mipInt + 1.0 );
return vec4( mix( color0, color1, mipF ), 1.0 );
}
}
`;