float shadows_highlights (float input,
float shadowsX,
float shadowsY,
float highlightsX,
float highlightsY)
{
float x = input;
float a = shadowsX;
float b = shadowsY;
float c = highlightsX;
float d = highlightsY;
float y0a = 0.00; // initial y
float x0a = 0.00; // initial x
float y1a = b; // 1st influence y
float x1a = a; // 1st influence x
float y2a = d; // 2nd influence y
float x2a = c; // 2nd influence x
float y3a = 1.00; // final y
float x3a = 1.00; // final x
float A = x3a - 3*x2a + 3*x1a - x0a;
float B = 3*x2a - 6*x1a + 3*x0a;
float C = 3*x1a - 3*x0a;
float D = x0a;
float E = y3a - 3*y2a + 3*y1a - y0a;
float F = 3*y2a - 6*y1a + 3*y0a;
float G = 3*y1a - 3*y0a;
float H = y0a;
// Solve for t given x (using Newton-Raphson), then solve for y given t.
// Assume for the first guess that t = x.
float currentt = x;
int nRefinementIterations = 5;
for (int i = 0; i < nRefinementIterations; i++)
{
float currentx = xFromT(currentt, A, B, C, D);
float currentslope = slopeFromT(currentt, A, B, C);
currentt -= (currentx - x) * (currentslope);
currentt = min(max(currentt, float(0)), float(1));
}
float y = yFromT (currentt, E, F, G, H);
return y;
}
double Bezier::findSplit(QPointF p, double minDistance) const
{
double bestT = 0;
double lastDistance = std::numeric_limits<int>::max();
double blen = computeCubicCurveLength(1.0, 24);
double increment = 1.0 / blen;
double minDSqd = minDistance * minDistance;
for (double t = 0; t <= 1; t += increment) {
double x = xFromT(t);
double y = yFromT(t);
double d = GraphicsUtils::distanceSqd(p, QPointF(x, y));
if (d >= lastDistance) {
if (d > minDSqd) continue;
break;
}
bestT = t;
lastDistance = d;
}
return bestT;
}
