Avoid copying for performance

example/blocks/blocks/font.go

@@ -41,7 +41,7 @@ func textWidth(str string) int {
 }
 
 func drawText(rt *ebiten.Image, str string, ox, oy, scale int, c color.Color) error {
-	parts := []ebiten.ImagePart{}
+	parts := make([]ebiten.ImagePart, 0, len(str))
 
 	locationX, locationY := 0, 0
 	for _, c := range str {

example/blocks/blocks/piece.go

@@ -144,7 +144,16 @@ const fieldBlockNumX = 10
 const fieldBlockNumY = 20
 
 func drawBlocks(r *ebiten.Image, blocks [][]BlockType, x, y int, clr ebiten.ColorM) error {
-	parts := []ebiten.ImagePart{}
+	l := 0
+	for _, blockCol := range blocks {
+		for _, block := range blockCol {
+			if block == BlockTypeNone {
+				continue
+			}
+			l++
+		}
+	}
+	parts := make([]ebiten.ImagePart, 0, l)
 	for i, blockCol := range blocks {
 		for j, block := range blockCol {
 			if block == BlockTypeNone {

image.go

@@ -63,11 +63,9 @@ func (i *innerImage) drawImage(c *opengl.Context, img *innerImage, options *Draw
 			},
 		}
 	}
-	geo := options.GeoM
-	clr := options.ColorM
 	w, h := img.size()
 	quads := &textureQuads{parts, w, h}
-	return i.framebuffer.DrawTexture(c, img.texture, quads, &geo, &clr)
+	return i.framebuffer.DrawTexture(c, img.texture, quads, &options.GeoM, &options.ColorM)
 }
 
 func u(x float64, width int) float32 {

internal/graphics/framebuffer.go

@@ -20,13 +20,13 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 )
 
-func orthoProjectionMatrix(left, right, bottom, top int) [4][4]float64 {
+func orthoProjectionMatrix(left, right, bottom, top int) *[4][4]float64 {
 	e11 := float64(2) / float64(right-left)
 	e22 := float64(2) / float64(top-bottom)
 	e14 := -1 * float64(right+left) / float64(right-left)
 	e24 := -1 * float64(top+bottom) / float64(top-bottom)
 
-	return [4][4]float64{
+	return &[4][4]float64{
 		{e11, 0, 0, e14},
 		{0, e22, 0, e24},
 		{0, 0, 1, 0},
@@ -77,7 +77,7 @@ func (f *Framebuffer) setAsViewport(c *opengl.Context) error {
 	return c.SetViewport(f.native, width, height)
 }
 
-func (f *Framebuffer) projectionMatrix() [4][4]float64 {
+func (f *Framebuffer) projectionMatrix() *[4][4]float64 {
 	width := internal.NextPowerOf2Int(f.width)
 	height := internal.NextPowerOf2Int(f.height)
 	m := orthoProjectionMatrix(0, width, 0, height)

internal/graphics/internal/shader/drawtexture.go

@@ -18,7 +18,7 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 )
 
-func glMatrix(m [4][4]float64) [16]float32 {
+func glMatrix(m *[4][4]float64) [16]float32 {
 	result := [16]float32{}
 	for j := 0; j < 4; j++ {
 		for i := 0; i < 4; i++ {
@@ -43,7 +43,7 @@ var initialized = false
 // TODO: Use unsafe.SizeOf?
 const float32Size = 4
 
-func DrawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix [4][4]float64, quads TextureQuads, geo Matrix, color Matrix) error {
+func DrawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix *[4][4]float64, quads TextureQuads, geo Matrix, color Matrix) error {
 	// TODO: Check len(quads) and gl.MAX_ELEMENTS_INDICES?
 	const stride = 4 * 4
 	if !initialized {