private void DrawColourwheel(float x, float y, float w, float h, float t)
{
float hue = MathF.Sin(t * 0.12f);
_nvg.Save();
float cx = x + w * 0.5f;
float cy = y + h * 0.5f;
float r1 = (w < h ? w : h) * 0.5f - 5.0f;
float r0 = r1 - 20.0f;
float aeps = 0.5f / r1;
Paint paint;
float ax, ay, bx, by;
for (int i = 0; i < 6; i++)
{
float a0 = (float)i / 6.0f * MathF.PI * 2.0f - aeps;
float a1 = (float)(i + 1.0f) / 6.0f * MathF.PI * 2.0f + aeps;
_nvg.BeginPath();
_nvg.Arc(cx, cy, r0, a0, a1, Winding.Cw);
_nvg.Arc(cx, cy, r1, a1, a0, Winding.Ccw);
_nvg.ClosePath();
ax = cx + MathF.Cos(a0) * (r0 + 1) * 0.5f;
ay = cy + MathF.Sin(a0) * (r0 + 1) * 0.5f;
bx = cx + MathF.Cos(a1) * (r0 + 1) * 0.5f;
by = cy + MathF.Sin(a1) * (r0 + 1) * 0.5f;
paint = _nvg.LinearGradient(ax, ay, bx, by, _nvg.Hsla(a0 / (MathF.PI * 2), 1.0f, 0.55f, 255), _nvg.Hsla(a1 / (MathF.PI * 2), 1.0f, 0.55f, 255));
_nvg.FillPaint(paint);
_nvg.Fill();
}
_nvg.BeginPath();
_nvg.Circle(cx, cy, r0 - 0.5f);
_nvg.Circle(cx, cy, r1 + 0.5f);
_nvg.StrokeColour(new Colour(0, 0, 0, 64));
_nvg.StrokeWidth(1.0f);
_nvg.Stroke();
_nvg.Save();
_nvg.Translate(cx, cy);
_nvg.Rotate(hue * MathF.PI * 2);
_nvg.StrokeWidth(2.0f);
_nvg.BeginPath();
_nvg.Rect(r0 - 1, -3, r1 - r0 + 2, 6);
_nvg.StrokeColour(new Colour(255, 255, 255, 255));
_nvg.Stroke();
paint = _nvg.BoxGradient(r0 - 3, -5, r1 - r0 + 6, 10, 2, 4, new Colour(0, 0, 0, 128), new Colour(0, 0, 0, 0));
_nvg.BeginPath();
_nvg.Rect(r0 - 2 - 10, -4 - 10, r1 - r0 + 4 + 20, 8 + 20);
_nvg.Rect(r0 - 2, -4, r1 - r0 + 4, 8);
_nvg.PathWinding(Solidity.Hole);
_nvg.FillPaint(paint);
_nvg.Fill();
float r = r0 - 6;
ax = MathF.Cos(120.0f / 180.0f * MathF.PI) * r;
ay = MathF.Sin(120.0f / 180.0f * MathF.PI) * r;
bx = MathF.Cos(-120.0f / 180.0f * MathF.PI) * r;
by = MathF.Sin(-120.0f / 180.0f * MathF.PI) * r;
_nvg.BeginPath();
_nvg.MoveTo(r, 0);
_nvg.LineTo(ax, ay);
_nvg.LineTo(bx, by);
_nvg.ClosePath();
paint = _nvg.LinearGradient(r, 0, ax, ay, _nvg.Hsla(hue, 1.0f, 0.5f, 255), _nvg.Rgba(255, 255, 255, 255));
_nvg.FillPaint(paint);
_nvg.Fill();
paint = _nvg.LinearGradient((r + ax) * 0.5f, (0 + ay) * 0.5f, bx, by, new Colour(0, 0, 0, 0), new Colour(0, 0, 0, 255));
_nvg.FillPaint(paint);
_nvg.Fill();
_nvg.StrokeColour(new Colour(0, 0, 0, 64));
_nvg.Stroke();
ax = MathF.Cos(120.0f / 180.0f * MathF.PI) * r * 0.3f;
ay = MathF.Sin(120.0f / 180.0f * MathF.PI) * r * 0.4f;
_nvg.StrokeWidth(2.0f);
_nvg.BeginPath();
_nvg.Circle(ax, ay, 5);
_nvg.StrokeColour(new Colour(255, 255, 255, 192));
_nvg.Stroke();
paint = _nvg.RadialGradient(ax, ay, 7, 9, new Colour(0, 0, 0, 64), new Colour(0, 0, 0, 0));
_nvg.BeginPath();
_nvg.Rect(ax - 20, ay - 20, 40, 40);
_nvg.Circle(ax, ay, 7);
_nvg.PathWinding(Solidity.Hole);
_nvg.FillPaint(paint);
_nvg.Fill();
_nvg.Restore();
_nvg.Restore();
}