public void Render(Graphics g, BezierSpline spline, float t)
{
// The basics: spline, control points, bounding polygon
if (OptionDrawSpline)
{
g.DrawBezier(SplinePen, spline.EntryPoint, spline.Control1, spline.Control2, spline.ExitPoint);
}
if (OptionDrawEntryPoint)
{
DrawPoint(g, spline.EntryPoint);
}
if (OptionDrawControlPoint1)
{
DrawPoint(g, spline.Control1);
}
if (OptionDrawControlPoint2)
{
DrawPoint(g, spline.Control2);
}
if (OptionDrawExitPoint)
{
DrawPoint(g, spline.ExitPoint);
}
if (OptionDrawBoundingPoly)
{
g.DrawLine(BoundingPolyPen, spline.EntryPoint, spline.Control1);
g.DrawLine(BoundingPolyPen, spline.Control1, spline.Control2);
g.DrawLine(BoundingPolyPen, spline.Control2, spline.ExitPoint);
g.DrawLine(BoundingPolyPen, spline.EntryPoint, spline.ExitPoint);
}
// Sample point
PointF sample = spline.EvalBezier(t);
if (OptionDrawSamplePoint)
{
g.FillEllipse(SamplePointBrush, sample.X - 2, sample.Y - 2, 4, 4);
}
// Tangent line
if (OptionDrawTangent)
{
PointF diff = spline.EvalBezierDiff(t);
if (diff.X == 0.0f)
{
g.DrawLine(TangentPen, sample.X, 0, sample.X, g.ClipBounds.Height);
}
else
{
float slope = diff.Y / diff.X;
float offset = sample.Y - (slope * sample.X);
g.DrawLine(TangentPen, 0, offset, g.ClipBounds.Width, ((float)g.ClipBounds.Width * slope) + offset);
}
}
// Normal vector
if (OptionDrawNormal)
{
PointF rawdiff = spline.EvalBezierDiff(t);
PointF diff = new PointF(-rawdiff.Y, rawdiff.X);
float length = (float)Math.Sqrt(diff.X * diff.X + diff.Y * diff.Y);
diff.X /= length;
diff.Y /= length;
diff.X *= 20.0f;
diff.Y *= 20.0f;
g.DrawLine(NormalPen, sample.X, sample.Y, sample.X - diff.X, sample.Y - diff.Y);
}
// Acceleration vector
if (OptionDrawAcceleration)
{
PointF diff2 = spline.EvalBezierSecondDiff(t);
float length = (float)Math.Sqrt(diff2.X * diff2.X + diff2.Y * diff2.Y);
diff2.X /= length;
diff2.Y /= length;
diff2.X *= 20.0f;
diff2.Y *= 20.0f;
g.DrawLine(AccelVecPen, sample.X, sample.Y, sample.X + diff2.X, sample.Y + diff2.Y);
}
}