cocos_lib/cocos/core/geometry/Spline.cpp

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#include "core/geometry/Spline.h"
#include <cmath>
#include "base/Log.h"
#include "base/Macros.h"
#include "base/memory/Memory.h"
#include "math/Utils.h"

namespace cc {
namespace geometry {

Spline::Spline(SplineMode mode /*= SplineMode::CATMULL_ROM*/, ccstd::vector<Vec3> knots /*= {}*/)
: ShapeBase(ShapeEnum::SHAPE_SPLINE), _mode(mode), _knots(std::move(knots)) {
}

Spline *Spline::create(SplineMode mode, const ccstd::vector<Vec3> &knots /*= {}*/) {
    return ccnew Spline(mode, knots);
}

Spline *Spline::clone(const Spline &s) {
    return ccnew Spline(s._mode, s._knots);
}

Spline *Spline::copy(Spline *out, const Spline &s) {
    out->_mode = s._mode;
    out->_knots = s._knots;

    return out;
}

void Spline::setModeAndKnots(SplineMode mode, const ccstd::vector<Vec3> &knots) {
    _mode = mode;
    _knots = knots;
}

void Spline::insertKnot(uint32_t index, const Vec3 &knot) {
    if (index >= static_cast<uint32_t>(_knots.size())) {
        _knots.push_back(knot);
        return;
    }

    _knots.insert(_knots.begin() + index, knot);
}

void Spline::removeKnot(uint32_t index) {
    CC_ASSERT(index < static_cast<uint32_t>(_knots.size()));

    _knots.erase(_knots.begin() + index);
}

void Spline::setKnot(uint32_t index, const Vec3 &knot) {
    CC_ASSERT(index < static_cast<uint32_t>(_knots.size()));

    _knots[index] = knot;
}

const Vec3 &Spline::getKnot(uint32_t index) const {
    CC_ASSERT(index < static_cast<uint32_t>(_knots.size()));

    return _knots[index];
}
Vec3 &Spline::getKnot(uint32_t index) {
    CC_ASSERT(index < static_cast<uint32_t>(_knots.size()));

    return _knots[index];
}

Vec3 Spline::getPoint(float t, uint32_t index /*= SPLINE_WHOLE_INDEX*/) const {
    t = mathutils::clamp(t, 0.0F, 1.0F);

    const auto segments = getSegments();
    if (segments == 0) {
        return Vec3(0.0F, 0.0F, 0.0F);
    }

    if (index == SPLINE_WHOLE_INDEX) {
        const auto deltaT = 1.0F / static_cast<float>(segments);

        index = static_cast<uint32_t>(t / deltaT);
        t = std::fmod(t, deltaT) / deltaT;
    }

    if (index >= segments) {
        return _knots.back();
    }

    switch (_mode) {
        case SplineMode::LINEAR:
            return calcLinear(_knots[index], _knots[index + 1], t);
        case SplineMode::BEZIER:
            return calcBezier(_knots[index * 4], _knots[index * 4 + 1], _knots[index * 4 + 2], _knots[index * 4 + 3], t);
        case SplineMode::CATMULL_ROM: {
            const auto v0 = index > 0 ? _knots[index - 1] : _knots[index];
            const auto v3 = index + 2 < static_cast<uint32_t>(_knots.size()) ? _knots[index + 2] : _knots[index + 1];
            return calcCatmullRom(v0, _knots[index], _knots[index + 1], v3, t);
        }
        default:
            return Vec3(0.0F, 0.0F, 0.0F);
    }
}

ccstd::vector<Vec3> Spline::getPoints(uint32_t num, uint32_t index /*= SPLINE_WHOLE_INDEX*/) const {
    if (num == 0U) {
        return {};
    }

    if (num == 1U) {
        auto point = getPoint(0.0F, index);
        return {point};
    }

    ccstd::vector<Vec3> points;
    const float deltaT = 1.0F / (static_cast<float>(num) - 1.0F);

    for (auto i = 0; i < num; i++) {
        const auto t = static_cast<float>(i) * deltaT;
        const auto point = getPoint(t, index);

        points.push_back(point);
    }

    return points;
}

uint32_t Spline::getSegments() const {
    const auto count = static_cast<uint32_t>(_knots.size());
    switch (_mode) {
        case SplineMode::LINEAR:
        case SplineMode::CATMULL_ROM:
            if (count < 2) {
                CC_LOG_WARNING("Spline error: less than 2 knots.");
                return 0;
            }

            return count - 1;
        case SplineMode::BEZIER:
            if (count < 4 || count % 4 != 0) {
                CC_LOG_WARNING("Spline error: less than 4 knots or not a multiple of 4.");
                return 0;
            }

            return count / 4;
        default:
            CC_ABORT();
            return 0;
    }
}

Vec3 Spline::calcLinear(const Vec3 &v0, const Vec3 &v1, float t) {
    const auto result = v0 * (1.0F - t) + v1 * t;

    return result;
}

Vec3 Spline::calcBezier(const Vec3 &v0, const Vec3 &v1, const Vec3 &v2, const Vec3 &v3, float t) {
    const auto s = 1.0F - t;
    const auto result = v0 * s * s * s +
                        v1 * 3.0F * t * s * s +
                        v2 * 3.0F * t * t * s +
                        v3 * t * t * t;

    return result;
}

Vec3 Spline::calcCatmullRom(const Vec3 &v0, const Vec3 &v1, const Vec3 &v2, const Vec3 &v3, float t) {
    const auto t2 = t * t;
    const auto t3 = t2 * t;
    const auto result = v0 * (-0.5F * t3 + t2 - 0.5F * t) +
                        v1 * (1.5F * t3 - 2.5F * t2 + 1.0F) +
                        v2 * (-1.5F * t3 + 2.0F * t2 + 0.5F * t) +
                        v3 * (0.5F * t3 - 0.5F * t2);

    return result;
}

} // namespace geometry
} // namespace cc