public static Affine NewRotation(double angRad, double rotationCenterX, double rotationCenterY)
{
return(Affine.New(AffinePlan.Translate(-rotationCenterX, -rotationCenterY),
AffinePlan.Rotate(angRad),
AffinePlan.Translate(rotationCenterX, rotationCenterY)
));
}
public static Affine NewRotationDeg(double degree, double rotationCenterX, double rotationCenterY)
{
return(Affine.New(AffinePlan.Translate(-rotationCenterX, -rotationCenterY),
AffinePlan.RotateDeg(degree),
AffinePlan.Translate(rotationCenterX, rotationCenterY)
));
}
//--------------------------------------------------------------------
public void init(double x0, double y0,
double rx, double ry,
double angle,
bool large_arc_flag,
bool sweep_flag,
double x2, double y2)
{
m_radii_ok = true;
if (rx < 0.0)
{
rx = -rx;
}
if (ry < 0.0)
{
ry = -rx;
}
// Calculate the middle point between
// the current and the final points
//------------------------
double dx2 = (x0 - x2) / 2.0;
double dy2 = (y0 - y2) / 2.0;
double cos_a = Math.Cos(angle);
double sin_a = Math.Sin(angle);
// Calculate (x1, y1)
//------------------------
double x1 = cos_a * dx2 + sin_a * dy2;
double y1 = -sin_a * dx2 + cos_a * dy2;
// Ensure radii are large enough
//------------------------
double prx = rx * rx;
double pry = ry * ry;
double px1 = x1 * x1;
double py1 = y1 * y1;
// Check that radii are large enough
//------------------------
double radii_check = px1 / prx + py1 / pry;
if (radii_check > 1.0)
{
rx = Math.Sqrt(radii_check) * rx;
ry = Math.Sqrt(radii_check) * ry;
prx = rx * rx;
pry = ry * ry;
if (radii_check > 10.0)
{
m_radii_ok = false;
}
}
// Calculate (cx1, cy1)
//------------------------
double sign = (large_arc_flag == sweep_flag) ? -1.0 : 1.0;
double sq = (prx * pry - prx * py1 - pry * px1) / (prx * py1 + pry * px1);
double coef = sign * Math.Sqrt((sq < 0) ? 0 : sq);
double cx1 = coef * ((rx * y1) / ry);
double cy1 = coef * -((ry * x1) / rx);
//
// Calculate (cx, cy) from (cx1, cy1)
//------------------------
double sx2 = (x0 + x2) / 2.0;
double sy2 = (y0 + y2) / 2.0;
double cx = sx2 + (cos_a * cx1 - sin_a * cy1);
double cy = sy2 + (sin_a * cx1 + cos_a * cy1);
// Calculate the start_angle (angle1) and the sweep_angle (dangle)
//------------------------
double ux = (x1 - cx1) / rx;
double uy = (y1 - cy1) / ry;
double vx = (-x1 - cx1) / rx;
double vy = (-y1 - cy1) / ry;
double p, n;
// Calculate the angle start
//------------------------
n = Math.Sqrt(ux * ux + uy * uy);
p = ux; // (1 * ux) + (0 * uy)
sign = (uy < 0) ? -1.0 : 1.0;
double v = p / n;
if (v < -1.0)
{
v = -1.0;
}
if (v > 1.0)
{
v = 1.0;
}
double start_angle = sign * Math.Acos(v);
// Calculate the sweep angle
//------------------------
n = Math.Sqrt((ux * ux + uy * uy) * (vx * vx + vy * vy));
p = ux * vx + uy * vy;
sign = (ux * vy - uy * vx < 0) ? -1.0 : 1.0;
v = p / n;
if (v < -1.0)
{
v = -1.0;
}
if (v > 1.0)
{
v = 1.0;
}
double sweep_angle = sign * Math.Acos(v);
if (!sweep_flag && sweep_angle > 0)
{
sweep_angle -= Math.PI * 2.0;
}
else
if (sweep_flag && sweep_angle < 0)
{
sweep_angle += Math.PI * 2.0;
}
// We can now build and transform the resulting arc
//------------------------
m_arc.init(0.0, 0.0, rx, ry, start_angle, sweep_angle);
Affine mtx = Affine.New(
AffinePlan.Rotate(angle),
AffinePlan.Translate(cx, cy)
);
for (int i = 2; i < m_arc.m_num_vertices - 2; i += 2)
{
mtx.Transform(ref m_arc.m_vertices[i], ref m_arc.m_vertices[i + 1]);
}
// We must make sure that the starting and ending points
// exactly coincide with the initial (x0,y0) and (x2,y2)
m_arc.m_vertices[0] = x0;
m_arc.m_vertices[1] = y0;
if (m_arc.m_num_vertices > 2)
{
m_arc.m_vertices[m_arc.m_num_vertices - 2] = x2;
m_arc.m_vertices[m_arc.m_num_vertices - 1] = y2;
}
}
