affine: Refactoring

internal/affine/affine.go

@@ -14,44 +14,30 @@
 
 package affine
 
-type affine interface {
-	dim() int
-	element(i, j int) float64
-	SetElement(i, j int, element float64)
-}
-
 // add is deprecated
-func add(lhs, rhs, result affine) {
+func add(lhs, rhs []float64, dim int) []float64 {
-	dim := lhs.dim()
+	result := make([]float64, len(lhs))
-	if dim != rhs.dim() {
-		panic("ebiten: different-sized matrices can't be multiplied")
-	}
-
 	for i := 0; i < dim-1; i++ {
 		for j := 0; j < dim; j++ {
-			v := lhs.element(i, j) + rhs.element(i, j)
+			result[i*dim+j] = lhs[i*dim+j] + rhs[i*dim+j]
-			result.SetElement(i, j, v)
 		}
 	}
+	return result
 }
 
-func mul(lhs, rhs, result affine) {
+func mul(lhs, rhs []float64, dim int) []float64 {
-	dim := lhs.dim()
+	result := make([]float64, len(lhs))
-	if dim != rhs.dim() {
-		panic("ebiten: different-sized matrices can't be multiplied")
-	}
-
 	for i := 0; i < dim-1; i++ {
 		for j := 0; j < dim; j++ {
-			element := float64(0)
+			e := 0.0
 			for k := 0; k < dim-1; k++ {
-				element += lhs.element(i, k) *
+				e += lhs[i*dim+k] * rhs[k*dim+j]
-					rhs.element(k, j)
 			}
 			if j == dim-1 {
-				element += lhs.element(i, j)
+				e += lhs[i*dim+j]
 			}
-			result.SetElement(i, j, element)
+			result[i*dim+j] = e
 		}
 	}
+	return result
 }

internal/affine/colorm.go

@@ -44,10 +44,6 @@ type ColorM struct {
 	elements []float64
 }
 
-func (c *ColorM) dim() int {
-	return ColorMDim
-}
-
 func (c *ColorM) UnsafeElements() []float64 {
 	if c.elements == nil {
 		c.elements = colorMIdentityElements
@@ -55,13 +51,6 @@ func (c *ColorM) UnsafeElements() []float64 {
 	return c.elements
 }
 
-func (c *ColorM) element(i, j int) float64 {
-	if c.elements == nil {
-		c.elements = colorMIdentityElements
-	}
-	return c.elements[i*ColorMDim+j]
-}
-
 // SetElement sets an element at (i, j).
 func (c *ColorM) SetElement(i, j int, element float64) {
 	if c.elements == nil {
@@ -94,16 +83,24 @@ func (c *ColorM) Equals(other *ColorM) bool {
 // Concat multiplies a color matrix with the other color matrix.
 // This is same as muptiplying the matrix other and the matrix c in this order.
 func (c *ColorM) Concat(other ColorM) {
-	result := ColorM{}
+	if c.elements == nil {
-	mul(&other, c, &result)
+		c.elements = colorMIdentityElements
-	*c = result
+	}
+	if other.elements == nil {
+		other.elements = colorMIdentityElements
+	}
+	c.elements = mul(other.elements, c.elements, ColorMDim)
 }
 
 // Add is deprecated.
 func (c *ColorM) Add(other ColorM) {
-	result := ColorM{}
+	if c.elements == nil {
-	add(&other, c, &result)
+		c.elements = colorMIdentityElements
-	*c = result
+	}
+	if other.elements == nil {
+		other.elements = colorMIdentityElements
+	}
+	c.elements = add(other.elements, c.elements, ColorMDim)
 }
 
 // Scale scales the matrix by (r, g, b, a).

internal/affine/geom.go

@@ -37,10 +37,6 @@ type GeoM struct {
 	elements []float64
 }
 
-func (g *GeoM) dim() int {
-	return GeoMDim
-}
-
 func (g *GeoM) UnsafeElements() []float64 {
 	if g.elements == nil {
 		g.elements = geoMIdentityElements
@@ -48,13 +44,6 @@ func (g *GeoM) UnsafeElements() []float64 {
 	return g.elements
 }
 
-func (g *GeoM) element(i, j int) float64 {
-	if g.elements == nil {
-		g.elements = geoMIdentityElements
-	}
-	return g.elements[i*GeoMDim+j]
-}
-
 // SetElement sets an element at (i, j).
 func (g *GeoM) SetElement(i, j int, element float64) {
 	if g.elements == nil {
@@ -69,16 +58,24 @@ func (g *GeoM) SetElement(i, j int, element float64) {
 // Concat multiplies a geometry matrix with the other geometry matrix.
 // This is same as muptiplying the matrix other and the matrix g in this order.
 func (g *GeoM) Concat(other GeoM) {
-	result := GeoM{}
+	if g.elements == nil {
-	mul(&other, g, &result)
+		g.elements = geoMIdentityElements
-	*g = result
+	}
+	if other.elements == nil {
+		other.elements = geoMIdentityElements
+	}
+	g.elements = mul(other.elements, g.elements, GeoMDim)
 }
 
 // Add is deprecated.
 func (g *GeoM) Add(other GeoM) {
-	result := GeoM{}
+	if g.elements == nil {
-	add(&other, g, &result)
+		g.elements = geoMIdentityElements
-	*g = result
+	}
+	if other.elements == nil {
+		other.elements = geoMIdentityElements
+	}
+	g.elements = add(other.elements, g.elements, GeoMDim)
 }
 
 // Scale scales the matrix by (x, y).