mirror of https://github.com/hyprwm/Hyprland
55 lines
1.6 KiB
C++
55 lines
1.6 KiB
C++
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#include "BezierCurve.hpp"
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void CBezierCurve::setup(std::vector<Vector2D>* pVec) {
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m_dPoints.clear();
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m_dPoints.emplace_back(Vector2D(0,0));
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for (auto& p : *pVec) {
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m_dPoints.push_back(p);
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}
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m_dPoints.emplace_back(Vector2D(1,1));
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RASSERT(m_dPoints.size() == 4, "CBezierCurve only supports cubic beziers! (points num: %i)", m_dPoints.size());
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// bake 100 points for faster lookups
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// T -> X ( / 100 )
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for (int i = 0; i < 100; ++i) {
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m_aPointsBaked[i] = getXForT((i + 1) / 100.f);
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}
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}
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float CBezierCurve::getYForT(float t) {
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return 3 * t * pow(1 - t, 2) * m_dPoints[1].y + 3 * pow(t, 2) * (1 - t) * m_dPoints[2].y + pow(t, 3);
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}
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float CBezierCurve::getXForT(float t) {
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return 3 * t * pow(1 - t, 2) * m_dPoints[1].x + 3 * pow(t, 2) * (1 - t) * m_dPoints[2].x + pow(t, 3);
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}
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// Todo: this probably can be done better and faster
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float CBezierCurve::getYForPoint(float x) {
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// binary search for the range UPDOWN X
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float upperX = 1;
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float lowerX = 0;
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float mid = 0.5;
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while(std::abs(upperX - lowerX) > 0.01f) {
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if (m_aPointsBaked[((int)(mid * 100.f))] > x) {
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upperX = mid;
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} else {
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lowerX = mid;
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}
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mid = (upperX + lowerX) / 2.f;
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}
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// in the name of performance i shall make a hack
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const auto PERCINDELTA = (x - m_aPointsBaked[(int)(100.f * lowerX)]) / (m_aPointsBaked[(int)(100.f * upperX)] - m_aPointsBaked[(int)(100.f * lowerX)]);
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if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA)) // can sometimes happen for VERY small x
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return 0.f;
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return getYForT(mid + PERCINDELTA * 0.01f);
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}
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