three
Version:
JavaScript 3D library
93 lines (73 loc) • 3.92 kB
JavaScript
export default /* glsl */`
// Single atlas 3D texture that stores all 7 SH sub-volumes stacked along Z.
// Atlas depth = 7 * ( nz + 2 ) where nz = probesResolution.z.
// Each sub-volume occupies ( nz + 2 ) slices: 1 padding + nz data + 1 padding.
// Padding is a copy of the first / last data slice and prevents color bleeding
// when the hardware linear filter reads across a sub-volume boundary.
uniform highp sampler3D probesSH[ NUM_LIGHT_PROBE_GRIDS ];
uniform vec3 probesMin[ NUM_LIGHT_PROBE_GRIDS ];
uniform vec3 probesMax[ NUM_LIGHT_PROBE_GRIDS ];
uniform vec3 probesResolution[ NUM_LIGHT_PROBE_GRIDS ];
bool isInsideLightProbeGrid( vec3 worldPos, vec3 worldNormal, vec3 probesMin, vec3 probesMax, vec3 probesResolution ) {
vec3 spacing = ( probesMax - probesMin ) / probesResolution;
vec3 samplePos = worldPos + worldNormal * spacing * 0.5;
// Grow the bounds by 1% of a cell, so fragments on the bounds aren't left out by
// precision errors or samples outside of the triangle.
vec3 margin = spacing * 0.01;
return all( greaterThanEqual( samplePos, probesMin - margin ) ) && all( lessThanEqual( samplePos, probesMax + margin ) );
}
vec3 getLightProbeGridIrradiance( highp sampler3D probesSH, vec3 probesMin, vec3 probesMax, vec3 probesResolution, vec3 worldPos, vec3 worldNormal ) {
vec3 res = probesResolution;
vec3 gridRange = probesMax - probesMin;
vec3 probeSpacing = gridRange / res;
// Offset sample position along normal by half a probe spacing
vec3 samplePos = worldPos + worldNormal * probeSpacing * 0.5;
// The bounds hold one cell per probe, so they map directly to the probe grid.
// Clamp to the texel centers of the outermost probes (XY and Z).
vec3 uvw = clamp( ( samplePos - probesMin ) / gridRange, 0.5 / res, 1.0 - 0.5 / res );
// Atlas UV mapping along Z:
// paddedSlices = nz + 2 (1 padding texel at each end of every sub-volume)
// atlasDepth = 7 * paddedSlices
// For sub-volume t the first DATA texel sits at atlas slice t*paddedSlices + 1.
// Given probe-grid texel-centre UVZ = ( iz + 0.5 ) / nz the atlas UV is:
// atlasUvZ = ( uvw.z * nz + t * paddedSlices + 1 ) / atlasDepth
//
// uvZBase encodes the nz-scaled Z plus the intra-volume offset (+ 1 for padding),
// so adding t*paddedSlices steps to each successive sub-volume.
float nz = res.z;
float paddedSlices = nz + 2.0;
float atlasDepth = 7.0 * paddedSlices;
float uvZBase = uvw.z * nz + 1.0;
vec4 s0 = texture( probesSH, vec3( uvw.xy, ( uvZBase ) / atlasDepth ) );
vec4 s1 = texture( probesSH, vec3( uvw.xy, ( uvZBase + paddedSlices ) / atlasDepth ) );
vec4 s2 = texture( probesSH, vec3( uvw.xy, ( uvZBase + 2.0 * paddedSlices ) / atlasDepth ) );
vec4 s3 = texture( probesSH, vec3( uvw.xy, ( uvZBase + 3.0 * paddedSlices ) / atlasDepth ) );
vec4 s4 = texture( probesSH, vec3( uvw.xy, ( uvZBase + 4.0 * paddedSlices ) / atlasDepth ) );
vec4 s5 = texture( probesSH, vec3( uvw.xy, ( uvZBase + 5.0 * paddedSlices ) / atlasDepth ) );
vec4 s6 = texture( probesSH, vec3( uvw.xy, ( uvZBase + 6.0 * paddedSlices ) / atlasDepth ) );
// Unpack 9 vec3 SH L2 coefficients
vec3 c0 = s0.xyz;
vec3 c1 = vec3( s0.w, s1.xy );
vec3 c2 = vec3( s1.zw, s2.x );
vec3 c3 = s2.yzw;
vec3 c4 = s3.xyz;
vec3 c5 = vec3( s3.w, s4.xy );
vec3 c6 = vec3( s4.zw, s5.x );
vec3 c7 = s5.yzw;
vec3 c8 = s6.xyz;
// Evaluate L2 irradiance
float x = worldNormal.x, y = worldNormal.y, z = worldNormal.z;
vec3 result = c0 * 0.886227;
result += c1 * 2.0 * 0.511664 * y;
result += c2 * 2.0 * 0.511664 * z;
result += c3 * 2.0 * 0.511664 * x;
result += c4 * 2.0 * 0.429043 * x * y;
result += c5 * 2.0 * 0.429043 * y * z;
result += c6 * ( 0.743125 * z * z - 0.247708 );
result += c7 * 2.0 * 0.429043 * x * z;
result += c8 * 0.429043 * ( x * x - y * y );
return max( result, vec3( 0.0 ) );
}
`;