From bf63d2310d18a33471a8f315731768a558ebd416 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 18 Mar 2023 10:17:13 +0900
Subject: [PATCH] ebitenutil: revert the implementation of Draw* functions

Using vector functions caused unexpected increase of draw calls.
Revert the Draw* functions to use regular DrawImage/DrawTriangles.

Closes #2605
---
 ebitenutil/shapes.go | 58 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/ebitenutil/shapes.go b/ebitenutil/shapes.go
index e2a86e7b5..5209bfbb6 100644
--- a/ebitenutil/shapes.go
+++ b/ebitenutil/shapes.go
@@ -15,35 +15,79 @@
 package ebitenutil
 
 import (
+	"image"
 	"image/color"
+	"math"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/vector"
 )
 
+var (
+	whiteImage    = ebiten.NewImage(3, 3)
+	whiteSubImage = whiteImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image)
+)
+
+func init() {
+	pix := make([]byte, 4*3*3)
+	for i := range pix {
+		pix[i] = 0xff
+	}
+	whiteImage.WritePixels(pix)
+}
+
 // DrawLine draws a line segment on the given destination dst.
 //
 // DrawLine is intended to be used mainly for debugging or prototyping purpose.
 //
-// Deprecated: as of v2.5. Use vector.StrokeLine instead.
+// Use vector.StrokeLine instead if you require rendering with higher quality.
 func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
-	vector.StrokeLine(dst, float32(x1), float32(y1), float32(x2), float32(y2), 1, clr)
+	length := math.Hypot(x2-x1, y2-y1)
+
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Scale(length, 1)
+	op.GeoM.Rotate(math.Atan2(y2-y1, x2-x1))
+	op.GeoM.Translate(x1, y1)
+	op.ColorM.ScaleWithColor(clr)
+	// Filter must be 'nearest' filter (default).
+	// Linear filtering would make edges blurred.
+	dst.DrawImage(whiteSubImage, op)
 }
 
 // DrawRect draws a rectangle on the given destination dst.
 //
 // DrawRect is intended to be used mainly for debugging or prototyping purpose.
 //
-// Deprecated: as of v2.5. Use vector.DrawFilledRect instead.
+// Use vector.DrawFilledRect instead if you require rendering with higher quality.
 func DrawRect(dst *ebiten.Image, x, y, width, height float64, clr color.Color) {
-	vector.DrawFilledRect(dst, float32(x), float32(y), float32(width), float32(height), clr)
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Scale(width, height)
+	op.GeoM.Translate(x, y)
+	op.ColorM.ScaleWithColor(clr)
+	// Filter must be 'nearest' filter (default).
+	// Linear filtering would make edges blurred.
+	dst.DrawImage(whiteImage.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 purpose.
+// DrawCircle is intended to be used mainly for debugging or prototyping puropose.
 //
-// Deprecated: as of v2.5. Use vector.DrawFilledCircle instead.
+// Use vector.DrawFilledCircle instead if you require rendering with higher quality.
 func DrawCircle(dst *ebiten.Image, cx, cy, r float64, clr color.Color) {
-	vector.DrawFilledCircle(dst, float32(cx), float32(cy), float32(r), clr)
+	var path vector.Path
+	rd, g, b, a := clr.RGBA()
+
+	path.Arc(float32(cx), float32(cy), float32(r), 0, 2*math.Pi, vector.Clockwise)
+
+	vertices, indices := path.AppendVerticesAndIndicesForFilling(nil, nil)
+	for i := range vertices {
+		vertices[i].SrcX = 1
+		vertices[i].SrcY = 1
+		vertices[i].ColorR = float32(rd) / 0xffff
+		vertices[i].ColorG = float32(g) / 0xffff
+		vertices[i].ColorB = float32(b) / 0xffff
+		vertices[i].ColorA = float32(a) / 0xffff
+	}
+	dst.DrawTriangles(vertices, indices, whiteSubImage, nil)
 }