Refactoring: matrix initialization

colorm.go

@@ -21,16 +21,6 @@ import (
 // ColorMDim is a dimension of a ColorM.
 const ColorMDim = 5
 
-var colorMI = ColorM{
-	initialized: true,
-	es: [ColorMDim - 1][ColorMDim]float64{
-		{1, 0, 0, 0, 0},
-		{0, 1, 0, 0, 0},
-		{0, 0, 1, 0, 0},
-		{0, 0, 0, 1, 0},
-	},
-}
-
 // A ColorM represents a matrix to transform coloring when rendering an image.
 //
 // A ColorM is applied to the source alpha color
@@ -48,6 +38,14 @@ func (c *ColorM) dim() int {
 	return ColorMDim
 }
 
+func (c *ColorM) initialize() {
+	c.initialized = true
+	c.es[0][0] = 1
+	c.es[1][1] = 1
+	c.es[2][2] = 1
+	c.es[3][3] = 1
+}
+
 // Element returns a value of a matrix at (i, j).
 func (c *ColorM) Element(i, j int) float64 {
 	if !c.initialized {
@@ -62,7 +60,7 @@ func (c *ColorM) Element(i, j int) float64 {
 // Concat multiplies a color matrix with the other color matrix.
 func (c *ColorM) Concat(other ColorM) {
 	if !c.initialized {
-		*c = colorMI
+		c.initialize()
 	}
 	result := ColorM{}
 	mul(&other, c, &result)
@@ -72,7 +70,7 @@ func (c *ColorM) Concat(other ColorM) {
 // Add adds a color matrix with the other color matrix.
 func (c *ColorM) Add(other ColorM) {
 	if !c.initialized {
-		*c = colorMI
+		c.initialize()
 	}
 	result := ColorM{}
 	add(&other, c, &result)
@@ -81,7 +79,7 @@ func (c *ColorM) Add(other ColorM) {
 
 func (c *ColorM) Scale(r, g, b, a float64) {
 	if !c.initialized {
-		*c = colorMI
+		c.initialize()
 	}
 	for i := 0; i < ColorMDim; i++ {
 		c.es[0][i] *= r
@@ -93,7 +91,7 @@ func (c *ColorM) Scale(r, g, b, a float64) {
 
 func (c *ColorM) Translate(r, g, b, a float64) {
 	if !c.initialized {
-		*c = colorMI
+		c.initialize()
 	}
 	c.es[0][4] += r
 	c.es[1][4] += g
@@ -104,7 +102,7 @@ func (c *ColorM) Translate(r, g, b, a float64) {
 // SetElement sets an element at (i, j).
 func (c *ColorM) SetElement(i, j int, element float64) {
 	if !c.initialized {
-		*c = colorMI
+		c.initialize()
 	}
 	c.es[i][j] = element
 }

example/blocks/blocks/gamescene.go

@@ -109,22 +109,24 @@ func (s *GameScene) drawBackground(r *ebiten.Image) error {
 	}
 
 	w, h := imageGameBG.Size()
-	geo := ebiten.TranslateGeo(-float64(w)/2, -float64(h)/2)
+	var geo ebiten.GeoM
+	geo.Translate(-float64(w)/2, -float64(h)/2)
 	scaleW := ScreenWidth / float64(w)
 	scaleH := ScreenHeight / float64(h)
 	scale := scaleW
 	if scale < scaleH {
 		scale = scaleH
 	}
-	geo.Concat(ebiten.ScaleGeo(scale, scale))
+	geo.Scale(scale, scale)
-	geo.Concat(ebiten.TranslateGeo(ScreenWidth/2, ScreenHeight/2))
+	geo.Translate(ScreenWidth/2, ScreenHeight/2)
 
 	a := 0.7
 	m := ebiten.Monochrome()
-	m.Concat(ebiten.ScaleColor(a, a, a, a))
+	m.Scale(a, a, a, a)
-	clr := ebiten.ScaleColor(1-a, 1-a, 1-a, 1-a)
+	var clr ebiten.ColorM
+	clr.Scale(1-a, 1-a, 1-a, 1-a)
 	clr.Add(m)
-	clr.Concat(ebiten.TranslateColor(0.3, 0.3, 0.3, 0))
+	clr.Translate(0.3, 0.3, 0.3, 0)
 	return r.DrawImage(imageGameBG, &ebiten.DrawImageOptions{
 		GeoM:   geo,
 		ColorM: clr,

geom.go

@@ -21,14 +21,6 @@ import (
 // GeoMDim is a dimension of a GeoM.
 const GeoMDim = 3
 
-var geoMI = GeoM{
-	initialized: true,
-	es: [2][3]float64{
-		{1, 0, 0},
-		{0, 1, 0},
-	},
-}
-
 // A GeoM represents a matrix to transform geometry when rendering an image.
 //
 // The initial value is identity.
@@ -41,6 +33,12 @@ func (g *GeoM) dim() int {
 	return GeoMDim
 }
 
+func (g *GeoM) initialize() {
+	g.initialized = true
+	g.es[0][0] = 1
+	g.es[1][1] = 1
+}
+
 // Element returns a value of a matrix at (i, j).
 func (g *GeoM) Element(i, j int) float64 {
 	if !g.initialized {
@@ -55,7 +53,7 @@ func (g *GeoM) Element(i, j int) float64 {
 // Concat multiplies a geometry matrix with the other geometry matrix.
 func (g *GeoM) Concat(other GeoM) {
 	if !g.initialized {
-		*g = geoMI
+		g.initialize()
 	}
 	result := GeoM{}
 	mul(&other, g, &result)
@@ -65,7 +63,7 @@ func (g *GeoM) Concat(other GeoM) {
 // Add adds a geometry matrix with the other geometry matrix.
 func (g *GeoM) Add(other GeoM) {
 	if !g.initialized {
-		*g = geoMI
+		g.initialize()
 	}
 	result := GeoM{}
 	add(&other, g, &result)
@@ -74,7 +72,7 @@ func (g *GeoM) Add(other GeoM) {
 
 func (g *GeoM) Scale(x, y float64) {
 	if !g.initialized {
-		*g = geoMI
+		g.initialize()
 	}
 	for i := 0; i < GeoMDim; i++ {
 		g.es[0][i] *= x
@@ -84,7 +82,7 @@ func (g *GeoM) Scale(x, y float64) {
 
 func (g *GeoM) Translate(tx, ty float64) {
 	if !g.initialized {
-		*g = geoMI
+		g.initialize()
 	}
 	g.es[0][2] += tx
 	g.es[1][2] += ty
@@ -93,7 +91,7 @@ func (g *GeoM) Translate(tx, ty float64) {
 // SetElement sets an element at (i, j).
 func (g *GeoM) SetElement(i, j int, element float64) {
 	if !g.initialized {
-		*g = geoMI
+		g.initialize()
 	}
 	g.es[i][j] = element
 }