animation: add CBezierCurve

include/hyprutils/animation/BezierCurve.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <array>
+#include <vector>
+
+#include "../math/Vector2D.hpp"
+
+constexpr int   BAKEDPOINTS    = 255;
+constexpr float INVBAKEDPOINTS = 1.f / BAKEDPOINTS;
+
+namespace Hyprutils {
+    namespace Animation {
+
+        /* An implementation of a cubic bezier curve. */
+        class CBezierCurve {
+          public:
+            /* Calculates a cubic bezier curve based on 2 control points (EXCLUDES the 0,0 and 1,1 points). */
+            void  setup(const std::array<Hyprutils::Math::Vector2D, 2>& points);
+
+            float getYForT(float const& t) const;
+            float getXForT(float const& t) const;
+            float getYForPoint(float const& x) const;
+
+          private:
+            /* this INCLUDES the 0,0 and 1,1 points. */
+            std::vector<Hyprutils::Math::Vector2D>             m_vPoints;
+
+            std::array<Hyprutils::Math::Vector2D, BAKEDPOINTS> m_aPointsBaked;
+        };
+    }
+}

src/animation/BezierCurve.cpp

@@ -0,0 +1,88 @@
+#include <hyprutils/animation/BezierCurve.hpp>
+
+#include <array>
+#include <cmath>
+
+using namespace Hyprutils::Animation;
+using namespace Hyprutils::Math;
+
+void CBezierCurve::setup(const std::array<Vector2D, 2>& pVec) {
+    //const auto BEGIN = std::chrono::high_resolution_clock::now();
+
+    // Avoid reallocations by reserving enough memory upfront
+    m_vPoints.resize(pVec.size() + 2);
+    m_vPoints = {
+        Vector2D(0, 0),   // Start point
+        pVec[0], pVec[1], // Control points
+        Vector2D(1, 1)    // End point
+    };
+
+    if (m_vPoints.size() != 4)
+        std::abort();
+
+    // bake BAKEDPOINTS points for faster lookups
+    // T -> X ( / BAKEDPOINTS )
+    for (int i = 0; i < BAKEDPOINTS; ++i) {
+        float const t     = (i + 1) / (float)BAKEDPOINTS;
+        m_aPointsBaked[i] = Vector2D(getXForT(t), getYForT(t));
+    }
+
+    //const auto ELAPSEDUS  = std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now() - BEGIN).count() / 1000.f;
+    //const auto POINTSSIZE = m_aPointsBaked.size() * sizeof(m_aPointsBaked[0]) / 1000.f;
+
+    //const auto BEGINCALC = std::chrono::high_resolution_clock::now();
+    for (int j = 1; j < 10; ++j) {
+        float i = j / 10.0f;
+        getYForPoint(i);
+    }
+    //const auto ELAPSEDCALCAVG = std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now() - BEGINCALC).count() / 1000.f / 10.f;
+
+    //Debug::log(LOG, "Created a bezier curve, baked {} points, mem usage: {:.2f}kB, time to bake: {:.2f}µs. Estimated average calc time: {:.2f}µs.", BAKEDPOINTS, POINTSSIZE,
+    //           ELAPSEDUS, ELAPSEDCALCAVG);
+}
+
+float CBezierCurve::getXForT(float const& t) const {
+    float t2 = t * t;
+    float t3 = t2 * t;
+
+    return 3 * t * (1 - t) * (1 - t) * m_vPoints[1].x + 3 * t2 * (1 - t) * m_vPoints[2].x + t3 * m_vPoints[3].x;
+}
+
+float CBezierCurve::getYForT(float const& t) const {
+    float t2 = t * t;
+    float t3 = t2 * t;
+
+    return 3 * t * (1 - t) * (1 - t) * m_vPoints[1].y + 3 * t2 * (1 - t) * m_vPoints[2].y + t3 * m_vPoints[3].y;
+}
+
+// Todo: this probably can be done better and faster
+float CBezierCurve::getYForPoint(float const& x) const {
+    if (x >= 1.f)
+        return 1.f;
+    if (x <= 0.f)
+        return 0.f;
+
+    int  index = 0;
+    bool below = true;
+    for (int step = (BAKEDPOINTS + 1) / 2; step > 0; step /= 2) {
+        if (below)
+            index += step;
+        else
+            index -= step;
+
+        below = m_aPointsBaked[index].x < x;
+    }
+
+    int lowerIndex = index - (!below || index == BAKEDPOINTS - 1);
+
+    // in the name of performance i shall make a hack
+    const auto LOWERPOINT = &m_aPointsBaked[lowerIndex];
+    const auto UPPERPOINT = &m_aPointsBaked[lowerIndex + 1];
+
+    const auto PERCINDELTA = (x - LOWERPOINT->x) / (UPPERPOINT->x - LOWERPOINT->x);
+
+    if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA)) // can sometimes happen for VERY small x
+        return 0.f;
+
+    return LOWERPOINT->y + (UPPERPOINT->y - LOWERPOINT->y) * PERCINDELTA;
+}