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#include "BezierCurve.hpp"
void CBezierCurve::setup(std::vector<Vector2D>* pVec) {
m_dPoints.clear();
const auto BEGIN = std::chrono::high_resolution_clock::now();
m_dPoints.emplace_back(Vector2D(0,0));
for (auto& p : *pVec) {
m_dPoints.push_back(p);
}
m_dPoints.emplace_back(Vector2D(1,1));
RASSERT(m_dPoints.size() == 4, "CBezierCurve only supports cubic beziers! (points num: %i)", m_dPoints.size());
// bake BAKEDPOINTS points for faster lookups
// T -> X ( / BAKEDPOINTS )
for (int i = 0; i < BAKEDPOINTS; ++i) {
m_aPointsBaked[i] = Vector2D(getXForT((i + 1) / (float)BAKEDPOINTS), getYForT((i + 1) / (float)BAKEDPOINTS));
}
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 (float i = 0.1f; i < 1.f; i += 0.1f)
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 %i points, mem usage: %.2fkB, time to bake: %.2fµs. Estimated average calc time: %.2fµs.",
BAKEDPOINTS, POINTSSIZE, ELAPSEDUS, ELAPSEDCALCAVG);
}
float CBezierCurve::getYForT(float t) {
return 3 * t * pow(1 - t, 2) * m_dPoints[1].y + 3 * pow(t, 2) * (1 - t) * m_dPoints[2].y + pow(t, 3);
}
float CBezierCurve::getXForT(float t) {
return 3 * t * pow(1 - t, 2) * m_dPoints[1].x + 3 * pow(t, 2) * (1 - t) * m_dPoints[2].x + pow(t, 3);
}
// Todo: this probably can be done better and faster
float CBezierCurve::getYForPoint(float x) {
// binary search for the range UPDOWN X
float upperT = 1;
float lowerT = 0;
float mid = 0.5;
while(std::abs(upperT - lowerT) > INVBAKEDPOINTS) {
if (m_aPointsBaked[((int)(mid * (float)BAKEDPOINTS))].x > x) {
upperT = mid;
} else {
lowerT = mid;
}
mid = (upperT + lowerT) / 2.f;
}
// in the name of performance i shall make a hack
const auto LOWERPOINT = &m_aPointsBaked[std::clamp((int)((float)BAKEDPOINTS * lowerT), 0, 199)];
const auto UPPERPOINT = &m_aPointsBaked[std::clamp((int)((float)BAKEDPOINTS * upperT), 0, 199)];
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 - UPPERPOINT->y) * PERCINDELTA;
}
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