static void DrawColorWheel(NanoVGContext vg, float x, float y, float w, float h, float t)
{
int i;
float r0, r1, ax, ay, bx, by, cx, cy, aeps, r;
float hue = (float)Math.Sin(t * 0.12f);
NVGPaint paint;
NVG.Save(vg);
cx = x + w * 0.5f;
cy = y + h * 0.5f;
r1 = (w < h ? w : h) * 0.5f - 5.0f;
r0 = r1 - 20.0f;
aeps = 0.5f / r1; // half a pixel arc length in radians (2pi cancels out).
for (i = 0; i < 6; i++)
{
float a0 = (float)i / 6.0f * (float)Math.PI * 2.0f - aeps;
float a1 = (float)(i + 1.0f) / 6.0f * (float)Math.PI * 2.0f + aeps;
NVG.BeginPath(vg);
NVG.Arc(vg, cx, cy, r0, a0, a1, NVGWinding.NVG_CW);
NVG.Arc(vg, cx, cy, r1, a1, a0, NVGWinding.NVG_CCW);
NVG.ClosePath(vg);
ax = cx + (float)Math.Cos(a0) * (r0 + r1) * 0.5f;
ay = cy + (float)Math.Sin(a0) * (r0 + r1) * 0.5f;
bx = cx + (float)Math.Cos(a1) * (r0 + r1) * 0.5f;
by = cy + (float)Math.Sin(a1) * (r0 + r1) * 0.5f;
paint = NVG.LinearGradient(vg, ax, ay, bx, by, NVG.HSLA(a0 / ((float)Math.PI * 2), 1.0f, 0.55f, 255), NVG.HSLA(a1 / ((float)Math.PI * 2), 1.0f, 0.55f, 255));
NVG.FillPaint(vg, paint);
NVG.Fill(vg);
}
NVG.BeginPath(vg);
NVG.Circle(vg, cx, cy, r0 - 0.5f);
NVG.Circle(vg, cx, cy, r1 + 0.5f);
NVG.StrokeColor(vg, NVG.RGBA(0, 0, 0, 64));
NVG.StrokeWidth(vg, 1.0f);
NVG.Stroke(vg);
// Selector
NVG.Save(vg);
NVG.Translate(vg, cx, cy);
NVG.Rotate(vg, hue * (float)Math.PI * 2);
// Marker on
NVG.StrokeWidth(vg, 2.0f);
NVG.BeginPath(vg);
NVG.Rect(vg, r0 - 1, -3, r1 - r0 + 2, 6);
NVG.StrokeColor(vg, NVG.RGBA(255, 255, 255, 192));
NVG.Stroke(vg);
paint = NVG.BoxGradient(vg, r0 - 3, -5, r1 - r0 + 6, 10, 2, 4, NVG.RGBA(0, 0, 0, 128), NVG.RGBA(0, 0, 0, 0));
NVG.BeginPath(vg);
NVG.Rect(vg, r0 - 2 - 10, -4 - 10, r1 - r0 + 4 + 20, 8 + 20);
NVG.Rect(vg, r0 - 2, -4, r1 - r0 + 4, 8);
NVG.PathWinding(vg, NVGSolidity.NVG_HOLE);
NVG.FillPaint(vg, paint);
NVG.Fill(vg);
// Center triangle
r = r0 - 6;
ax = (float)Math.Cos(120.0f / 180.0f * (float)Math.PI) * r;
ay = (float)Math.Sin(120.0f / 180.0f * (float)Math.PI) * r;
bx = (float)Math.Cos(-120.0f / 180.0f * (float)Math.PI) * r;
by = (float)Math.Sin(-120.0f / 180.0f * (float)Math.PI) * r;
NVG.BeginPath(vg);
NVG.MoveTo(vg, r, 0);
NVG.LineTo(vg, ax, ay);
NVG.LineTo(vg, bx, by);
NVG.ClosePath(vg);
paint = NVG.LinearGradient(vg, r, 0, ax, ay, NVG.HSLA(hue, 1.0f, 0.5f, 255), NVG.RGBA(255, 255, 255, 255));
NVG.FillPaint(vg, paint);
NVG.Fill(vg);
paint = NVG.LinearGradient(vg, (r + ax) * 0.5f, (0 + ay) * 0.5f, bx, by, NVG.RGBA(0, 0, 0, 0), NVG.RGBA(0, 0, 0, 255));
NVG.FillPaint(vg, paint);
NVG.Fill(vg);
NVG.StrokeColor(vg, NVG.RGBA(0, 0, 0, 64));
NVG.Stroke(vg);
// Select circle on triangle
ax = (float)Math.Cos(120.0f / 180.0f * (float)Math.PI) * r * 0.3f;
ay = (float)Math.Sin(120.0f / 180.0f * (float)Math.PI) * r * 0.4f;
NVG.StrokeWidth(vg, 2.0f);
NVG.BeginPath(vg);
NVG.Circle(vg, ax, ay, 5);
NVG.StrokeColor(vg, NVG.RGBA(255, 255, 255, 192));
NVG.Stroke(vg);
paint = NVG.RadialGradient(vg, ax, ay, 7, 9, NVG.RGBA(0, 0, 0, 64), NVG.RGBA(0, 0, 0, 0));
NVG.BeginPath(vg);
NVG.Rect(vg, ax - 20, ay - 20, 40, 40);
NVG.Circle(vg, ax, ay, 7);
NVG.PathWinding(vg, NVGSolidity.NVG_HOLE);
NVG.FillPaint(vg, paint);
NVG.Fill(vg);
NVG.Restore(vg);
NVG.Restore(vg);
}