gg: add draw_polygon_filled fn with rotation parameter (#14867)

vlib/gg/draw.c.v

@@ -521,36 +521,46 @@ pub fn (ctx &Context) draw_circle_empty(x f32, y f32, radius f32, c gx.Color) {
 // `radius` defines the radius of the circle.
 // `c` is the fill color.
 pub fn (ctx &Context) draw_circle_filled(x f32, y f32, radius f32, c gx.Color) {
-	ctx.draw_circle_with_segments(x, y, radius, radius_to_segments(radius), c)
+	ctx.draw_polygon_filled(x, y, radius, radius_to_segments(radius), 0, c)
 }
 
-// draw_circle_with_segments draws a filled circle with a specific number of segments.
-// `x`,`y` defines the center of the circle.
-// `radius` defines the radius of the circle.
-// `segments` affects how smooth/round the circle is.
+// draw_polygon_filled draws a filled polygon.
+// `x`,`y` defines the center of the polygon.
+// `size` defines the size of the polygon.
+// `edge` defines edge number of the polygon.
+// `rotation` defines rotation of the polygon.
 // `c` is the fill color.
-pub fn (ctx &Context) draw_circle_with_segments(x f32, y f32, radius f32, segments int, c gx.Color) {
+pub fn (ctx &Context) draw_polygon_filled(x f32, y f32, size f32, edge int, rotation f32, c gx.Color) {
 	if c.a != 255 {
 		sgl.load_pipeline(ctx.timage_pip)
 	}
 	sgl.c4b(c.r, c.g, c.b, c.a)
 	nx := x * ctx.scale
 	ny := y * ctx.scale
-	nr := radius * ctx.scale
+	nr := size * ctx.scale
 	mut theta := f32(0)
 	mut xx := f32(0)
 	mut yy := f32(0)
 	sgl.begin_triangle_strip()
-	for i := 0; i < segments + 1; i++ {
-		theta = 2.0 * f32(math.pi) * f32(i) / f32(segments)
-		xx = nr * math.cosf(theta)
-		yy = nr * math.sinf(theta)
+	for i := 0; i < edge + 1; i++ {
+		theta = 2.0 * f32(math.pi) * f32(i) / f32(edge)
+		xx = nr * math.cosf(theta + f32(math.radians(rotation)))
+		yy = nr * math.sinf(theta + f32(math.radians(rotation)))
 		sgl.v2f(xx + nx, yy + ny)
 		sgl.v2f(nx, ny)
 	}
 	sgl.end()
 }
 
+// draw_circle_with_segments draws a filled circle with a specific number of segments.
+// `x`,`y` defines the center of the circle.
+// `radius` defines the radius of the circle.
+// `segments` affects how smooth/round the circle is.
+// `c` is the fill color.
+pub fn (ctx &Context) draw_circle_with_segments(x f32, y f32, radius f32, segments int, c gx.Color) {
+	ctx.draw_polygon_filled(x, y, radius, segments, 0, c)
+}
+
 // draw_circle_line draws the outline of a circle with a specific number of segments.
 // `x`,`y` defines the center of the circle.
 // `radius` defines the radius of the circle.