public static int stbtt__solve_cubic(float a, float b, float c, float *r)
{
float s = -a / 3;
float p = b - a * a / 3;
float q = a * (2 * a * a - 9 * b) / 27 + c;
float p3 = p * p * p;
float d = q * q + 4 * p3 / 27;
if ((d) >= (0))
{
float z = (float)(CRuntime.Sqrt(d));
float u = (-q + z) / 2;
float v = (-q - z) / 2;
u = stbtt__cuberoot(u);
v = stbtt__cuberoot(v);
r[0] = s + u + v;
return(1);
}
else
{
float u = (float)(CRuntime.Sqrt(-p / 3));
float v = (float)(CRuntime.Acos(-CRuntime.Sqrt(-27 / p3) * q / 2)) / 3;
float m = (float)(CRuntime.Cos(v));
float n = (float)(CRuntime.Cos(v - 3.141592 / 2)) * 1.732050808f;
r[0] = s + u * 2 * m;
r[1] = s - u * (m + n);
r[2] = s - u * (m - n);
return(3);
}
}
public static void stbtt__tesselate_cubic(stbtt__point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3, float objspace_flatness_squared, int n)
{
float dx0 = x1 - x0;
float dy0 = y1 - y0;
float dx1 = x2 - x1;
float dy1 = y2 - y1;
float dx2 = x3 - x2;
float dy2 = y3 - y2;
float dx = x3 - x0;
float dy = y3 - y0;
float longlen = (float)(CRuntime.Sqrt(dx0 * dx0 + dy0 * dy0) + CRuntime.Sqrt(dx1 * dx1 + dy1 * dy1) + CRuntime.Sqrt(dx2 * dx2 + dy2 * dy2));
float shortlen = (float)(CRuntime.Sqrt(dx * dx + dy * dy));
float flatness_squared = longlen * longlen - shortlen * shortlen;
if ((n) > (16))
{
return;
}
if ((flatness_squared) > (objspace_flatness_squared))
{
float x01 = (x0 + x1) / 2;
float y01 = (y0 + y1) / 2;
float x12 = (x1 + x2) / 2;
float y12 = (y1 + y2) / 2;
float x23 = (x2 + x3) / 2;
float y23 = (y2 + y3) / 2;
float xa = (x01 + x12) / 2;
float ya = (y01 + y12) / 2;
float xb = (x12 + x23) / 2;
float yb = (y12 + y23) / 2;
float mx = (xa + xb) / 2;
float my = (ya + yb) / 2;
stbtt__tesselate_cubic(points, num_points, x0, y0, x01, y01, xa, ya, mx, my, objspace_flatness_squared, n + 1);
stbtt__tesselate_cubic(points, num_points, mx, my, xb, yb, x23, y23, x3, y3, objspace_flatness_squared, n + 1);
}
else
{
stbtt__add_point(points, *num_points, x3, y3);
*num_points = *num_points + 1;
}
}
public static int stbtt__ray_intersect_bezier(float *orig, float *ray, float *q0, float *q1, float *q2, float *hits)
{
float q0perp = q0[1] * ray[0] - q0[0] * ray[1];
float q1perp = q1[1] * ray[0] - q1[0] * ray[1];
float q2perp = q2[1] * ray[0] - q2[0] * ray[1];
float roperp = orig[1] * ray[0] - orig[0] * ray[1];
float a = q0perp - 2 * q1perp + q2perp;
float b = q1perp - q0perp;
float c = q0perp - roperp;
float s0 = 0;
float s1 = 0;
int num_s = 0;
if (a != 0.0)
{
float discr = b * b - a * c;
if ((discr) > (0.0))
{
float rcpna = -1 / a;
float d = (float)(CRuntime.Sqrt(discr));
s0 = (b + d) * rcpna;
s1 = (b - d) * rcpna;
if (((s0) >= (0.0)) && (s0 <= 1.0))
{
num_s = 1;
}
if ((((d) > (0.0)) && ((s1) >= (0.0))) && (s1 <= 1.0))
{
if ((num_s) == (0))
{
s0 = s1;
}
++num_s;
}
}
}
else
{
s0 = c / (-2 * b);
if (((s0) >= (0.0)) && (s0 <= 1.0))
{
num_s = 1;
}
}
if ((num_s) == (0))
{
return(0);
}
else
{
float rcp_len2 = 1 / (ray[0] * ray[0] + ray[1] * ray[1]);
float rayn_x = ray[0] * rcp_len2;
float rayn_y = ray[1] * rcp_len2;
float q0d = q0[0] * rayn_x + q0[1] * rayn_y;
float q1d = q1[0] * rayn_x + q1[1] * rayn_y;
float q2d = q2[0] * rayn_x + q2[1] * rayn_y;
float rod = orig[0] * rayn_x + orig[1] * rayn_y;
float q10d = q1d - q0d;
float q20d = q2d - q0d;
float q0rd = q0d - rod;
hits[0] = q0rd + s0 * (2.0f - 2.0f * s0) * q10d + s0 * s0 * q20d;
hits[1] = a * s0 + b;
if ((num_s) > (1))
{
hits[2] = q0rd + s1 * (2.0f - 2.0f * s1) * q10d + s1 * s1 * q20d;
hits[3] = a * s1 + b;
return(2);
}
else
{
return(1);
}
}
}
