137 lines
4.2 KiB
137 lines
4.2 KiB
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/****************************************************************************
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Copyright (c) 2022-2023 Xiamen Yaji Software Co., Ltd.
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http://www.cocos.com
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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of the Software, and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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****************************************************************************/
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#pragma once
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#include <cmath>
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#include <functional>
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#include "base/std/container/vector.h"
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#include "core/TypedArray.h"
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#include "math/Math.h"
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#include "math/Vec3.h"
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namespace cc {
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namespace gi {
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#define SH_BASIS_COUNT 9
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class LightProbeSampler {
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public:
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/**
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* generate one sample from sphere uniformly
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*/
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static Vec3 uniformSampleSphere(float u1, float u2);
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/**
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* generate ucount1 * ucount2 samples from sphere uniformly
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*/
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static ccstd::vector<Vec3> uniformSampleSphereAll(uint32_t sampleCount);
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/**
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* probability density function of uniform distribution on spherical surface
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*/
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static inline float uniformSpherePdf() { return 1.0F / (4.0F * math::PI); }
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};
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/**
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* Spherical Harmonics utility class
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*/
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class SH {
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public:
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using BasisFunction = std::function<float(const Vec3& v)>;
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/**
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* update ubo data by coefficients
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*/
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static void updateUBOData(Float32Array& data, int32_t offset, ccstd::vector<Vec3>& coefficients);
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/**
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* recreate a function from sh coefficients, which is same as SHEvaluate in shader
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*/
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static Vec3 shaderEvaluate(const Vec3& normal, ccstd::vector<Vec3>& coefficients);
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/**
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* recreate a function from sh coefficients
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*/
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static Vec3 evaluate(const Vec3& sample, const ccstd::vector<Vec3>& coefficients);
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/**
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* project a function to sh coefficients
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*/
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static ccstd::vector<Vec3> project(const ccstd::vector<Vec3>& samples, const ccstd::vector<Vec3>& values);
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/**
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* calculate irradiance's sh coefficients from radiance's sh coefficients directly
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*/
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static ccstd::vector<Vec3> convolveCosine(const ccstd::vector<Vec3>& radianceCoefficients);
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/**
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* return basis function count
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*/
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static inline uint32_t getBasisCount() {
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return SH_BASIS_COUNT;
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}
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/**
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* evaluate from a basis function
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*/
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static inline float evaluateBasis(uint32_t index, const Vec3& sample) {
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CC_ASSERT(index < getBasisCount());
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const auto& func = basisFunctions[index];
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return func(sample);
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}
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static inline void reduceRinging(ccstd::vector<Vec3>& coefficients, float lambda) {
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if (lambda == 0.0F) {
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return;
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}
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for (int32_t l = 0; l <= LMAX; ++l) {
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auto level = static_cast<float>(l);
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float scale = 1.0F / (1.0F + lambda * level * level * (level + 1) * (level + 1));
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for (int32_t m = -l; m <= l; ++m) {
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const int32_t i = toIndex(l, m);
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coefficients[i] *= scale;
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}
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}
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}
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private:
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static inline float lambda(int32_t l) {
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return std::sqrt((4.0F * math::PI) / (2.0F * static_cast<float>(l) + 1.0F));
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}
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static inline int32_t toIndex(int32_t l, int32_t m) {
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return l * l + l + m;
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}
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static constexpr int32_t LMAX = 2;
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static ccstd::vector<BasisFunction> basisFunctions;
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static ccstd::vector<float> basisOverPI;
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};
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} // namespace gi
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} // namespace cc
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