Improve bezier baking & approx

This commit is contained in:
vaxerski 2022-05-12 16:59:51 +02:00
parent 1d21e5303b
commit bef4d7c9b7
2 changed files with 14 additions and 11 deletions

View file

@ -18,7 +18,7 @@ void CBezierCurve::setup(std::vector<Vector2D>* pVec) {
// bake BAKEDPOINTS points for faster lookups // bake BAKEDPOINTS points for faster lookups
// T -> X ( / BAKEDPOINTS ) // T -> X ( / BAKEDPOINTS )
for (int i = 0; i < BAKEDPOINTS; ++i) { for (int i = 0; i < BAKEDPOINTS; ++i) {
m_aPointsBaked[i] = getXForT((i + 1) / (float)BAKEDPOINTS); 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 ELAPSEDUS = std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now() - BEGIN).count() / 1000.f;
@ -45,25 +45,28 @@ float CBezierCurve::getXForT(float t) {
// Todo: this probably can be done better and faster // Todo: this probably can be done better and faster
float CBezierCurve::getYForPoint(float x) { float CBezierCurve::getYForPoint(float x) {
// binary search for the range UPDOWN X // binary search for the range UPDOWN X
float upperX = 1; float upperT = 1;
float lowerX = 0; float lowerT = 0;
float mid = 0.5; float mid = 0.5;
while(std::abs(upperX - lowerX) > INVBAKEDPOINTS) { while(std::abs(upperT - lowerT) > INVBAKEDPOINTS) {
if (m_aPointsBaked[((int)(mid * (float)BAKEDPOINTS))] > x) { if (m_aPointsBaked[((int)(mid * (float)BAKEDPOINTS))].x > x) {
upperX = mid; upperT = mid;
} else { } else {
lowerX = mid; lowerT = mid;
} }
mid = (upperX + lowerX) / 2.f; mid = (upperT + lowerT) / 2.f;
} }
// in the name of performance i shall make a hack // in the name of performance i shall make a hack
const auto PERCINDELTA = (x - m_aPointsBaked[(int)((float)BAKEDPOINTS * lowerX)]) / (m_aPointsBaked[(int)((float)BAKEDPOINTS * upperX)] - m_aPointsBaked[(int)((float)BAKEDPOINTS * lowerX)]); const auto LOWERPOINT = &m_aPointsBaked[(int)((float)BAKEDPOINTS * lowerT)];
const auto UPPERPOINT = &m_aPointsBaked[(int)((float)BAKEDPOINTS * upperT)];
const auto PERCINDELTA = (x - LOWERPOINT->x) / (UPPERPOINT->x - LOWERPOINT->x);
if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA)) // can sometimes happen for VERY small x if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA)) // can sometimes happen for VERY small x
return 0.f; return 0.f;
return getYForT(mid + PERCINDELTA * INVBAKEDPOINTS); return LOWERPOINT->y + (UPPERPOINT->y - UPPERPOINT->y) * PERCINDELTA;
} }

View file

@ -23,5 +23,5 @@ private:
// this INCLUDES the 0,0 and 1,1 points. // this INCLUDES the 0,0 and 1,1 points.
std::deque<Vector2D> m_dPoints; std::deque<Vector2D> m_dPoints;
std::array<float, BAKEDPOINTS> m_aPointsBaked; std::array<Vector2D, BAKEDPOINTS> m_aPointsBaked;
}; };