ebitenutil: add DrawCircle (hajimehoshi#2175)

Closes hajimehoshi#2163
brobits · Jul 3, 2022 · a249296 · a249296
1 parent c31cc4e
commit a249296
Showing 1 changed file with 22 additions and 0 deletions.
diff --git a/ebitenutil/shapes.go b/ebitenutil/shapes.go
@@ -20,6 +20,7 @@ import (
 	"math"
 
 	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/vector"
 )
 
 var (
@@ -59,3 +60,24 @@ func DrawRect(dst *ebiten.Image, x, y, width, height float64, clr color.Color) {
 	// Linear filtering would make edges blurred.
 	dst.DrawImage(emptyImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image), op)
 }
+
+// DrawCircle draws a circle on given destination dst.
+//
+// DrawCircle is intended to be used mainly for debugging or prototyping puropose.
+func DrawCircle(dst *ebiten.Image, cx, cy, r float64, clr color.Color) {
+	var path vector.Path
+	rd, g, b, a := clr.RGBA()
+
+	path.Arc(float32(cx), float32(cy), float32(r), 0, 2*math.Pi, vector.Clockwise)
+
+	verticles, indices := path.AppendVerticesAndIndicesForFilling(nil, nil)
+	for i := range verticles {
+		verticles[i].SrcX = 1
+		verticles[i].SrcY = 1
+		verticles[i].ColorR = float32(rd) / 0xffff
+		verticles[i].ColorG = float32(g) / 0xffff
+		verticles[i].ColorB = float32(b) / 0xffff
+		verticles[i].ColorA = float32(a) / 0xffff
+	}
+	dst.DrawTriangles(verticles, indices, emptySubImage, nil)
+}