106 lines
3.1 KiB
JavaScript
106 lines
3.1 KiB
JavaScript
//This file is automatically rebuilt by the Cesium build process.
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export default "uniform samplerCube u_radianceMap;\n\
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\n\
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in vec2 v_textureCoordinates;\n\
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\n\
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\n\
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const float twoSqrtPi = 2.0 * sqrt(czm_pi);\n\
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\n\
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// Coutesy of https://www.ppsloan.org/publications/StupidSH36.pdf\n\
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float computeShBasis(int index, vec3 s) {\n\
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if (index == 0) { // l = 0, m = 0\n\
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return 1.0 / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 1) { // l = 1, m = -1\n\
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return -sqrt(3.0) * s.y / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 2) { // l = 1, m = 0\n\
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return sqrt(3.0) * s.z / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 3) { // l = 1, m = 1\n\
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return -sqrt(3.0) * s.x / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 4) { // l = 2, m = -2\n\
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return sqrt(15.0) * s.y * s.x / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 5) { // l = 2, m = -1\n\
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return -sqrt(15.0) * s.y * s.z / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 6) { // l = 2, m = 0\n\
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return sqrt(5.0) * (3.0 * s.z * s.z - 1.0) / 2.0 / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 7) { // l = 2, m = 1\n\
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return -sqrt(15.0) * s.x * s.z / twoSqrtPi;\n\
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}\n\
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\n\
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if (index == 8) { // l = 2, m = 2\n\
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return sqrt(15.0) * (s.x * s.x - s.y * s.y) / 2.0 / twoSqrtPi;\n\
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}\n\
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\n\
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return 0.0;\n\
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}\n\
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\n\
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float vdcRadicalInverse(int i)\n\
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{\n\
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float r;\n\
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float base = 2.0;\n\
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float value = 0.0;\n\
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float invBase = 1.0 / base;\n\
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float invBi = invBase;\n\
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for (int x = 0; x < 100; x++)\n\
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{\n\
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if (i <= 0)\n\
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{\n\
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break;\n\
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}\n\
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r = mod(float(i), base);\n\
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value += r * invBi;\n\
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invBi *= invBase;\n\
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i = int(float(i) * invBase);\n\
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}\n\
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return value;\n\
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}\n\
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\n\
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vec2 hammersley2D(int i, int N)\n\
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{\n\
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return vec2(float(i) / float(N), vdcRadicalInverse(i));\n\
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}\n\
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\n\
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// Sample count is relatively low for the sake of performance, but should still be enough to capture directionality needed for third-order harmonics\n\
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const int samples = 256; \n\
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const float solidAngle = 1.0 / float(samples);\n\
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\n\
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void main() {\n\
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// Get the current coefficient based on the uv\n\
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vec2 uv = v_textureCoordinates.xy * 3.0;\n\
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int coefficientIndex = int(floor(uv.y) * 3.0 + floor(uv.x));\n\
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\n\
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for (int i = 0; i < samples; ++i) {\n\
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vec2 xi = hammersley2D(i, samples);\n\
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float phi = czm_twoPi * xi.x;\n\
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float cosTheta = 1.0 - 2.0 * sqrt(1.0 - xi.y * xi.y);\n\
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float sinTheta = sqrt(1.0 - cosTheta * cosTheta);\n\
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vec3 direction = normalize(vec3(sinTheta * cos(phi), cosTheta, sinTheta * sin(phi)));\n\
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\n\
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// Generate the spherical harmonics basis from the direction\n\
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float Ylm = computeShBasis(coefficientIndex, direction);\n\
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\n\
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vec3 lookupDirection = -direction.xyz;\n\
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lookupDirection.z = -lookupDirection.z;\n\
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\n\
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vec4 color = czm_textureCube(u_radianceMap, lookupDirection, 0.0);\n\
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\n\
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// Use the relevant function for this coefficient\n\
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out_FragColor += Ylm * color * solidAngle * sinTheta;\n\
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}\n\
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\n\
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}\n\
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";
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