static void
rsvg_path_arc_segment (RSVGParsePathCtx *ctx,
double xc, double yc,
double th0, double th1,
double rx, double ry, double x_axis_rotation)
{
double sin_th, cos_th;
double a00, a01, a10, a11;
double x1, y1, x2, y2, x3, y3;
double t;
double th_half;
sin_th = sin (x_axis_rotation * (M_PI / 180.0));
cos_th = cos (x_axis_rotation * (M_PI / 180.0));
/* inverse transform compared with rsvg_path_arc */
a00 = cos_th * rx;
a01 = -sin_th * ry;
a10 = sin_th * rx;
a11 = cos_th * ry;
th_half = 0.5 * (th1 - th0);
t = (8.0 / 3.0) * sin (th_half * 0.5) * sin (th_half * 0.5) / sin (th_half);
x1 = xc + cos (th0) - t * sin (th0);
y1 = yc + sin (th0) + t * cos (th0);
x3 = xc + cos (th1);
y3 = yc + sin (th1);
x2 = x3 + t * sin (th1);
y2 = y3 - t * cos (th1);
rsvg_bpath_def_curveto (ctx->bpath,
a00 * x1 + a01 * y1, a10 * x1 + a11 * y1,
a00 * x2 + a01 * y2, a10 * x2 + a11 * y2,
a00 * x3 + a01 * y3, a10 * x3 + a11 * y3);
}
static void
rsvg_path_arc_segment (RSVGParsePathCtx * ctx,
double xc, double yc,
double th0, double th1, double rx, double ry,
double x_axis_rotation)
{
double x1, y1, x2, y2, x3, y3;
double t;
double th_half;
double f, sinf, cosf;
f = x_axis_rotation * M_PI / 180.0;
sinf = sin(f);
cosf = cos(f);
th_half = 0.5 * (th1 - th0);
t = (8.0 / 3.0) * sin (th_half * 0.5) * sin (th_half * 0.5) / sin (th_half);
x1 = rx*(cos (th0) - t * sin (th0));
y1 = ry*(sin (th0) + t * cos (th0));
x3 = rx*cos (th1);
y3 = ry*sin (th1);
x2 = x3 + rx*(t * sin (th1));
y2 = y3 + ry*(-t * cos (th1));
rsvg_bpath_def_curveto (ctx->bpath,
xc + cosf*x1 - sinf*y1,
yc + sinf*x1 + cosf*y1,
xc + cosf*x2 - sinf*y2,
yc + sinf*x2 + cosf*y2,
xc + cosf*x3 - sinf*y3,
yc + sinf*x3 + cosf*y3);
}
