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 Copyright (c) 2022-2023 Xiamen Yaji Software Co., Ltd.

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#include "LightProbe.h"
#include "PolynomialSolver.h"
#include "core/Root.h"
#include "core/scene-graph/Node.h"
#include "core/scene-graph/Scene.h"
#include "math/Math.h"
#include "math/Utils.h"
#include "renderer/pipeline/custom/RenderInterfaceTypes.h"

namespace cc {
namespace gi {

void LightProbesData::updateProbes(ccstd::vector<Vec3> &points) {
    _probes.clear();

    auto pointCount = points.size();
    _probes.reserve(pointCount);
    for (auto i = 0; i < pointCount; i++) {
        _probes.emplace_back(points[i]);
    }
}

void LightProbesData::updateTetrahedrons() {
    Delaunay delaunay(_probes);
    _tetrahedrons = delaunay.build();
}

bool LightProbesData::getInterpolationSHCoefficients(int32_t tetIndex, const Vec4 &weights, ccstd::vector<Vec3> &coefficients) const {
    if (!hasCoefficients()) {
        return false;
    }

    const auto length = SH::getBasisCount();
    coefficients.resize(length);

    const auto &tetrahedron = _tetrahedrons[tetIndex];
    const auto &c0 = _probes[tetrahedron.vertex0].coefficients;
    const auto &c1 = _probes[tetrahedron.vertex1].coefficients;
    const auto &c2 = _probes[tetrahedron.vertex2].coefficients;

    if (tetrahedron.vertex3 >= 0) {
        const auto &c3 = _probes[tetrahedron.vertex3].coefficients;

        for (auto i = 0; i < length; i++) {
            coefficients[i] = c0[i] * weights.x + c1[i] * weights.y + c2[i] * weights.z + c3[i] * weights.w;
        }
    } else {
        for (auto i = 0; i < length; i++) {
            coefficients[i] = c0[i] * weights.x + c1[i] * weights.y + c2[i] * weights.z;
        }
    }

    return true;
}

int32_t LightProbesData::getInterpolationWeights(const Vec3 &position, int32_t tetIndex, Vec4 &weights) const {
    const auto tetrahedronCount = _tetrahedrons.size();
    if (tetIndex < 0 || tetIndex >= tetrahedronCount) {
        tetIndex = 0;
    }

    int32_t lastIndex = -1;
    int32_t nextIndex = -1;

    for (auto i = 0; i < tetrahedronCount; i++) {
        const auto &tetrahedron = _tetrahedrons[tetIndex];
        getBarycentricCoord(position, tetrahedron, weights);
        if (weights.x >= 0.0F && weights.y >= 0.0F && weights.z >= 0.0F && weights.w >= 0.0F) {
            break;
        }

        if (weights.x < weights.y && weights.x < weights.z && weights.x < weights.w) {
            nextIndex = tetrahedron.neighbours[0];
        } else if (weights.y < weights.z && weights.y < weights.w) {
            nextIndex = tetrahedron.neighbours[1];
        } else if (weights.z < weights.w) {
            nextIndex = tetrahedron.neighbours[2];
        } else {
            nextIndex = tetrahedron.neighbours[3];
        }

        // return directly due to numerical precision error
        if (lastIndex == nextIndex) {
            break;
        }

        lastIndex = tetIndex;
        tetIndex = nextIndex;
    }

    return tetIndex;
}

Vec3 LightProbesData::getTriangleBarycentricCoord(const Vec3 &p0, const Vec3 &p1, const Vec3 &p2, const Vec3 &position) {
    Vec3 normal;
    Vec3::cross(p1 - p0, p2 - p0, &normal);

    if (normal.lengthSquared() <= mathutils::EPSILON) {
        return Vec3(0.0F, 0.0F, 0.0F);
    }

    const Vec3 n = normal.getNormalized();
    const float area012Inv = 1.0F / (n.dot(normal));

    Vec3 crossP12;
    Vec3::cross(p1 - position, p2 - position, &crossP12);
    const float areaP12 = n.dot(crossP12);
    const float alpha = areaP12 * area012Inv;

    Vec3 crossP20;
    Vec3::cross(p2 - position, p0 - position, &crossP20);
    const float areaP20 = n.dot(crossP20);
    const float beta = areaP20 * area012Inv;

    return Vec3(alpha, beta, 1.0F - alpha - beta);
}

void LightProbesData::getBarycentricCoord(const Vec3 &position, const Tetrahedron &tetrahedron, Vec4 &weights) const {
    if (tetrahedron.vertex3 >= 0) {
        getTetrahedronBarycentricCoord(position, tetrahedron, weights);
    } else {
        getOuterCellBarycentricCoord(position, tetrahedron, weights);
    }
}

void LightProbesData::getTetrahedronBarycentricCoord(const Vec3 &position, const Tetrahedron &tetrahedron, Vec4 &weights) const {
    Vec3 result = position - _probes[tetrahedron.vertex3].position;
    result.transformMat3(result, tetrahedron.matrix);

    weights.set(result.x, result.y, result.z, 1.0F - result.x - result.y - result.z);
}

void LightProbesData::getOuterCellBarycentricCoord(const Vec3 &position, const Tetrahedron &tetrahedron, Vec4 &weights) const {
    const auto &p0 = _probes[tetrahedron.vertex0].position;
    const auto &p1 = _probes[tetrahedron.vertex1].position;
    const auto &p2 = _probes[tetrahedron.vertex2].position;

    Vec3 normal;
    const auto edge1 = p1 - p0;
    const auto edge2 = p2 - p0;
    Vec3::cross(edge1, edge2, &normal);
    float t = Vec3::dot(position - p0, normal);
    if (t < 0.0F) {
        // test tetrahedron in next iterator
        weights.set(0.0F, 0.0F, 0.0F, -1.0F);
        return;
    }

    Vec3 coefficients;
    coefficients.transformMat3(position, tetrahedron.matrix);
    coefficients += tetrahedron.offset;

    if (tetrahedron.vertex3 == -1) {
        t = PolynomialSolver::getCubicUniqueRoot(coefficients.x, coefficients.y, coefficients.z);
    } else {
        t = PolynomialSolver::getQuadraticUniqueRoot(coefficients.x, coefficients.y, coefficients.z);
    }

    const auto v0 = p0 + _probes[tetrahedron.vertex0].normal * t;
    const auto v1 = p1 + _probes[tetrahedron.vertex1].normal * t;
    const auto v2 = p2 + _probes[tetrahedron.vertex2].normal * t;
    const auto result = getTriangleBarycentricCoord(v0, v1, v2, position);

    weights.set(result.x, result.y, result.z, 0.0F);
}

void LightProbes::initialize(LightProbeInfo *info) {
    _giScale = info->getGIScale();
    _giSamples = info->getGISamples();
    _bounces = info->getBounces();
    _reduceRinging = info->getReduceRinging();
    _showProbe = info->isShowProbe();
    _showWireframe = info->isShowWireframe();
    _lightProbeSphereVolume = info->getLightProbeSphereVolume();
    _showConvex = info->isShowConvex();
    _data = info->getData();
}

void LightProbeInfo::activate(Scene *scene, LightProbes *resource) {
    _scene = scene;
    _resource = resource;
    _resource->initialize(this);
}

void LightProbeInfo::onProbeBakeFinished() {
    onProbeBakingChanged(_scene);
}

void LightProbeInfo::onProbeBakeCleared() {
    clearSHCoefficients();
    onProbeBakingChanged(_scene);
}

void LightProbeInfo::clearSHCoefficients() {
    if (!_data) {
        return;
    }

    auto &probes = _data->getProbes();
    for (auto &probe : probes) {
        probe.coefficients.clear();
    }

    clearAllSHUBOs();
}

bool LightProbeInfo::addNode(Node *node) {
    if (!node) {
        return false;
    }

    for (auto &item : _nodes) {
        if (item.node == node) {
            return false;
        }
    }

    _nodes.emplace_back(node);

    return true;
}

bool LightProbeInfo::removeNode(Node *node) {
    if (!node) {
        return false;
    }

    for (auto iter = _nodes.begin(); iter != _nodes.end(); ++iter) {
        if (iter->node == node) {
            _nodes.erase(iter);
            return true;
        }
    }

    return false;
}

void LightProbeInfo::syncData(Node *node, const ccstd::vector<Vec3> &probes) {
    for (auto &item : _nodes) {
        if (item.node == node) {
            item.probes = probes;
            return;
        }
    }
}

void LightProbeInfo::update(bool updateTet) {
    if (!_data) {
        _data = new LightProbesData();
        if (_resource) {
            _resource->setData(_data);
        }
    }

    ccstd::vector<Vec3> points;

    for (auto &item : _nodes) {
        auto *node = item.node;
        auto &probes = item.probes;
        const auto &worldPosition = node->getWorldPosition();

        for (auto &probe : probes) {
            points.push_back(probe + worldPosition);
        }
    }

    auto pointCount = points.size();
    if (pointCount < 4) {
        resetAllTetraIndices();
        _data->reset();
        return;
    }

    _data->updateProbes(points);

    if (updateTet) {
        resetAllTetraIndices();
        _data->updateTetrahedrons();
    }
}

void LightProbeInfo::onProbeBakingChanged(Node *node) { // NOLINT(misc-no-recursion)
    if (!node) {
        return;
    }

    node->emit<Node::LightProbeBakingChanged>();

    const auto &children = node->getChildren();
    for (const auto &child: children) {
        onProbeBakingChanged(child);
    }
}

void LightProbeInfo::clearAllSHUBOs() {
    if (!_scene) {
        return;
    }

    auto *renderScene = _scene->getRenderScene();
    if (!renderScene) {
        return;
    }

    for (const auto &model : renderScene->getModels()) {
        model->clearSHUBOs();
    }
}

void LightProbeInfo::resetAllTetraIndices() {
    if (!_scene) {
        return;
    }

    auto *renderScene = _scene->getRenderScene();
    if (!renderScene) {
        return;
    }

    for (const auto &model : renderScene->getModels()) {
        model->setTetrahedronIndex(-1);
    }
}

} // namespace gi
} // namespace cc