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Fix BezierCurve edge cases

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Freevatar 2025-11-02 09:27:41 -05:00
parent 3df7bde01e
commit a584202c87
1 changed files with 33 additions and 19 deletions
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52
src/animation/BezierCurve.cpp
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@ -26,20 +26,15 @@ void CBezierCurve::setup4(const std::array<Vector2D, 4>& pVec) {
pVec[3],
};
if (m_vPoints.size() != 4)
std::abort();
// bake BAKEDPOINTS points for faster lookups
// T -> X ( / BAKEDPOINTS )
// Pre-bake curve
//
// We start baking at t=(i+1)/n not at t=0
// That means the first baked x can be > 0 if curve itself starts at x>0
for (int i = 0; i < BAKEDPOINTS; ++i) {
float const t = (i + 1) / sc<float>(BAKEDPOINTS);
// When i=0 -> t=1/255
const float t = (i + 1) * INVBAKEDPOINTS;
m_aPointsBaked[i] = Vector2D(getXForT(t), getYForT(t));
}
for (int j = 1; j < 10; ++j) {
float i = j / 10.0f;
getYForPoint(i);
}
}
float CBezierCurve::getXForT(float const& t) const {
@ -53,7 +48,7 @@ float CBezierCurve::getYForT(float const& t) const {
float t2 = t * t;
float t3 = t2 * t;
return ((1 - t) * (1 - t) * (1 - t) * m_vPoints[0].y) +(3 * t * (1 - t) * (1 - t) * m_vPoints[1].y) + (3 * t2 * (1 - t) * m_vPoints[2].y) + (t3 * m_vPoints[3].y);
return ((1 - t) * (1 - t) * (1 - t) * m_vPoints[0].y) + (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
@ -71,21 +66,40 @@ float CBezierCurve::getYForPoint(float const& x) const {
else
index -= step;
// Clamp to avoid index walking off
if (index < 0)
index = 0;
else if (index > BAKEDPOINTS - 1)
index = BAKEDPOINTS - 1;
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];
// Clamp final indices
if (lowerIndex < 0)
lowerIndex = 0;
else if (lowerIndex > BAKEDPOINTS - 2)
lowerIndex = BAKEDPOINTS - 2;
const auto PERCINDELTA = (x - LOWERPOINT->x) / (UPPERPOINT->x - LOWERPOINT->x);
// In the name of performance I shall make a hack
const auto& LOWERPOINT = m_aPointsBaked[lowerIndex];
const auto& UPPERPOINT = m_aPointsBaked[lowerIndex + 1];
if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA)) // can sometimes happen for VERY small x
return 0.f;
const float dx = (UPPERPOINT.x - LOWERPOINT.x);
// If two baked points have almost the same x
// just return the lower one
if (dx <= 1e-6f)
return LOWERPOINT.y;
return LOWERPOINT->y + ((UPPERPOINT->y - LOWERPOINT->y) * PERCINDELTA);
const auto PERCINDELTA = (x - LOWERPOINT.x) / dx;
// Can sometimes happen for VERY small x
if (std::isnan(PERCINDELTA) || std::isinf(PERCINDELTA))
return LOWERPOINT.y;
return LOWERPOINT.y + ((UPPERPOINT.y - LOWERPOINT.y) * PERCINDELTA);
}
const std::vector<Hyprutils::Math::Vector2D>& CBezierCurve::getControlPoints() const {