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114 lines
4.2 KiB
Diff
114 lines
4.2 KiB
Diff
From 3b7208caffa1362e43eff57d58b86d38e484193b Mon Sep 17 00:00:00 2001
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From: Tom Englund <tomenglund26@gmail.com>
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Date: Tue, 19 Nov 2024 18:46:03 +0100
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Subject: [PATCH] bezier: optimize setup of bezier curves
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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avoid reallocations by resizing and copy the pVec into the resized
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m_dPoints, reduce the amount of calculations in baking to only do it
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once per iteration instead of twice. precompute in getYforT and getXforT
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return early in getYForPoint if x is equal or below 0. and use const
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references where we can.
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these changes we are now down to an average of "time to bake: 2.50µs."
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on my machine compared to before average of "time to bake: 11.15µs"
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---
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src/helpers/BezierCurve.cpp | 35 ++++++++++++++++++++---------------
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src/helpers/BezierCurve.hpp | 8 ++++----
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2 files changed, 24 insertions(+), 19 deletions(-)
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diff --git a/src/helpers/BezierCurve.cpp b/src/helpers/BezierCurve.cpp
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index ea567ad61ca..0ef0883f805 100644
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--- a/src/helpers/BezierCurve.cpp
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+++ b/src/helpers/BezierCurve.cpp
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@@ -6,24 +6,21 @@
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#include <algorithm>
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void CBezierCurve::setup(std::vector<Vector2D>* pVec) {
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- m_dPoints.clear();
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-
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const auto BEGIN = std::chrono::high_resolution_clock::now();
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- m_dPoints.emplace_back(Vector2D(0, 0));
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-
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- for (auto const& p : *pVec) {
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- m_dPoints.push_back(p);
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- }
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-
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- m_dPoints.emplace_back(Vector2D(1, 1));
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+ // Avoid reallocations by reserving enough memory upfront
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+ m_dPoints.resize(pVec->size() + 2);
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+ m_dPoints[0] = Vector2D(0, 0); // Start point
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+ std::copy(pVec->begin(), pVec->end(), m_dPoints.begin() + 1);
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+ m_dPoints.back() = Vector2D(1, 1); // End point
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RASSERT(m_dPoints.size() == 4, "CBezierCurve only supports cubic beziers! (points num: {})", m_dPoints.size());
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// bake BAKEDPOINTS points for faster lookups
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// T -> X ( / BAKEDPOINTS )
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for (int i = 0; i < BAKEDPOINTS; ++i) {
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- m_aPointsBaked[i] = Vector2D(getXForT((i + 1) / (float)BAKEDPOINTS), getYForT((i + 1) / (float)BAKEDPOINTS));
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+ float const t = (i + 1) / (float)BAKEDPOINTS;
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+ m_aPointsBaked[i] = Vector2D(getXForT(t), getYForT(t));
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}
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const auto ELAPSEDUS = std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now() - BEGIN).count() / 1000.f;
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@@ -40,18 +37,26 @@ void CBezierCurve::setup(std::vector<Vector2D>* pVec) {
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ELAPSEDUS, ELAPSEDCALCAVG);
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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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+float CBezierCurve::getXForT(float const& t) {
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+ float t2 = t * t;
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+ float t3 = t2 * t;
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+
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+ return 3 * t * (1 - t) * (1 - t) * m_dPoints[1].x + 3 * t2 * (1 - t) * m_dPoints[2].x + t3 * m_dPoints[3].x;
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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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+float CBezierCurve::getYForT(float const& t) {
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+ float t2 = t * t;
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+ float t3 = t2 * t;
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+
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+ return 3 * t * (1 - t) * (1 - t) * m_dPoints[1].y + 3 * t2 * (1 - t) * m_dPoints[2].y + t3 * m_dPoints[3].y;
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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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+float CBezierCurve::getYForPoint(float const& x) {
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if (x >= 1.f)
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return 1.f;
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+ if (x <= 0.f)
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+ return 0.f;
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int index = 0;
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bool below = true;
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diff --git a/src/helpers/BezierCurve.hpp b/src/helpers/BezierCurve.hpp
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index 54af46a6b0f..1a842f5a833 100644
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--- a/src/helpers/BezierCurve.hpp
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+++ b/src/helpers/BezierCurve.hpp
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@@ -16,13 +16,13 @@ class CBezierCurve {
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// this EXCLUDES the 0,0 and 1,1 points,
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void setup(std::vector<Vector2D>* points);
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- float getYForT(float t);
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- float getXForT(float t);
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- float getYForPoint(float x);
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+ float getYForT(float const& t);
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+ float getXForT(float const& t);
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+ float getYForPoint(float const& x);
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private:
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// this INCLUDES the 0,0 and 1,1 points.
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- std::deque<Vector2D> m_dPoints;
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+ std::vector<Vector2D> m_dPoints;
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std::array<Vector2D, BAKEDPOINTS> m_aPointsBaked;
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};
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