Change GeometryMatrix's methods to functions

ebitenutil/debugprint.go

@@ -55,7 +55,7 @@ func (d *debugPrintState) drawText(gr ebiten.GraphicsContext, str string, x, y i
 		locationX += assets.TextImageCharWidth
 	}
 	geom := ebiten.GeometryMatrixI()
-	geom.Translate(float64(x)+1, float64(y))
+	geom.Concat(ebiten.TranslateGeometry(float64(x)+1, float64(y)))
 	clrm := ebiten.ColorMatrixI()
 	clrm.Scale(clr)
 	gr.Texture(d.textTexture).Draw(parts, geom, clrm)

example/blocks/blocks/font.go

@@ -56,8 +56,8 @@ func drawText(context ebiten.GraphicsContext, textures *Textures, str string, x,
 	}
 
 	geoMat := ebiten.GeometryMatrixI()
-	geoMat.Scale(float64(scale), float64(scale))
-	geoMat.Translate(float64(x), float64(y))
+	geoMat.Concat(ebiten.ScaleGeometry(float64(scale), float64(scale)))
+	geoMat.Concat(ebiten.TranslateGeometry(float64(x), float64(y)))
 	clrMat := ebiten.ColorMatrixI()
 	clrMat.Scale(clr)
 	context.Texture(fontTextureId).Draw(parts, geoMat, clrMat)

example/blocks/blocks/gamescene.go

@@ -116,16 +116,14 @@ func (s *GameScene) Draw(context ebiten.GraphicsContext, textures *Textures) {
 
 	field := textures.GetTexture("empty")
 	geoMat := ebiten.GeometryMatrixI()
-	geoMat.Scale(
-		float64(fieldWidth)/float64(emptyWidth),
-		float64(fieldHeight)/float64(emptyHeight))
-	geoMat.Translate(20, 20) // magic number?
+	geoMat.Concat(ebiten.ScaleGeometry(float64(fieldWidth)/float64(emptyWidth), float64(fieldHeight)/float64(emptyHeight)))
+	geoMat.Concat(ebiten.TranslateGeometry(20, 20)) // TODO: magic number?
 	colorMat := ebiten.ColorMatrixI()
 	colorMat.Scale(color.RGBA{0, 0, 0, 0x80})
 	ebiten.DrawWhole(context.Texture(field), emptyWidth, emptyHeight, geoMat, colorMat)
 
 	geoMat = ebiten.GeometryMatrixI()
-	geoMat.Translate(20, 20)
+	geoMat.Concat(ebiten.TranslateGeometry(20, 20))
 	s.field.Draw(context, textures, geoMat)
 
 	if s.currentPiece != nil {

example/blocks/blocks/piece.go

@@ -234,7 +234,7 @@ func (p *Piece) Draw(context ebiten.GraphicsContext, textures *Textures, fieldX,
 	geoMat := ebiten.GeometryMatrixI()
 	x := fieldX + pieceX*blockWidth
 	y := fieldY + pieceY*blockHeight
-	geoMat.Translate(float64(x), float64(y))
+	geoMat.Concat(ebiten.TranslateGeometry(float64(x), float64(y)))
 
 	drawBlocks(context, textures, blocks, geoMat)
 }

example/blocks/blocks/titlescene.go

@@ -69,7 +69,7 @@ func drawTitleBackground(context ebiten.GraphicsContext, textures *Textures, c i
 	dx := (-c / 4) % textureWidth
 	dy := (c / 4) % textureHeight
 	geo := ebiten.GeometryMatrixI()
-	geo.Translate(float64(dx), float64(dy))
+	geo.Concat(ebiten.TranslateGeometry(float64(dx), float64(dy)))
 	clr := ebiten.ColorMatrixI()
 	context.Texture(backgroundTextureId).Draw(parts, geo, clr)
 }

example/paint/main.go

@@ -55,7 +55,7 @@ func (g *Game) Draw(gr ebiten.GraphicsContext) error {
 	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
 		gr.PushRenderTarget(g.canvasRenderTarget)
 		geo := ebiten.GeometryMatrixI()
-		geo.Translate(float64(mx), float64(my))
+		geo.Concat(ebiten.TranslateGeometry(float64(mx), float64(my)))
 		clr := ebiten.ColorMatrixI()
 		clr.Scale(color.RGBA{0xff, 0xff, 0x00, 0xff})
 		theta := 2.0 * math.Pi * float64(g.count%60) / 60.0

geometrymatrix.go

@@ -63,30 +63,33 @@ func (g *GeometryMatrix) setElement(i, j int, element float64) {
 	g.Elements[i][j] = element
 }
 
-// Translate translates the geometry matrix by (tx, ty).
-func (g *GeometryMatrix) Translate(tx, ty float64) {
-	g.Elements[0][2] += tx
-	g.Elements[1][2] += ty
+// ScaleGeometry returns a matrix that scales a geometry matrix by (x, y).
+func ScaleGeometry(x, y float64) GeometryMatrix {
+	return GeometryMatrix{
+		[2][3]float64{
+			{x, 0, 0},
+			{0, y, 0},
+		},
+	}
 }
 
-// Scale scales the geometry matrix by (x, y).
-func (g *GeometryMatrix) Scale(x, y float64) {
-	g.Elements[0][0] *= x
-	g.Elements[0][1] *= x
-	g.Elements[0][2] *= x
-	g.Elements[1][0] *= y
-	g.Elements[1][1] *= y
-	g.Elements[1][2] *= y
+// TranslateGeometry returns a matrix taht translates a geometry matrix by (tx, ty).
+func TranslateGeometry(tx, ty float64) GeometryMatrix {
+	return GeometryMatrix{
+		[2][3]float64{
+			{1, 0, tx},
+			{0, 1, ty},
+		},
+	}
 }
 
-// Rotate rotates the geometry matrix by theta.
-func (g *GeometryMatrix) Rotate(theta float64) {
+// RotateGeometry returns a matrix that rotates a geometry matrix by theta.
+func RotateGeometry(theta float64) GeometryMatrix {
 	sin, cos := math.Sincos(theta)
-	rotate := GeometryMatrix{
+	return GeometryMatrix{
 		[2][3]float64{
 			{cos, -sin, 0},
 			{sin, cos, 0},
 		},
 	}
-	g.Concat(rotate)
 }

graphicscontext.go

@@ -101,7 +101,7 @@ func (c *graphicsContext) postUpdate() {
 
 	scale := float64(c.screenScale)
 	geo := GeometryMatrixI()
-	geo.Scale(scale, scale)
+	geo.Concat(ScaleGeometry(scale, scale))
 	DrawWhole(c.RenderTarget(c.screenID), c.screenWidth, c.screenHeight, geo, ColorMatrixI())
 
 	gl.Flush()