diff --git a/examples/sprites/main.go b/examples/sprites/main.go
index e7b5472ad..83a89e20d 100644
--- a/examples/sprites/main.go
+++ b/examples/sprites/main.go
@@ -105,13 +105,13 @@ var sprites = &Sprites{make([]*Sprite, MaxSprites), 500}
 
 func update(screen *ebiten.Image) error {
 	if ebiten.IsKeyPressed(ebiten.KeyLeft) {
-		sprites.num -= 100
+		sprites.num -= 20
 		if sprites.num < MinSprites {
 			sprites.num = MinSprites
 		}
 	}
 	if ebiten.IsKeyPressed(ebiten.KeyRight) {
-		sprites.num += 100
+		sprites.num += 20
 		if MaxSprites < sprites.num {
 			sprites.num = MaxSprites
 		}
diff --git a/internal/graphics/command.go b/internal/graphics/command.go
index a5c603014..162724fe0 100644
--- a/internal/graphics/command.go
+++ b/internal/graphics/command.go
@@ -58,6 +58,9 @@ func (q *commandQueue) Enqueue(command command) {
 	q.commands = append(q.commands, command)
 }
 
+// commandGroups separates q.commands into some groups.
+// The number of quads of drawImageCommand in one groups must be equal to or less than
+// its limit (maxQuads).
 func (q *commandQueue) commandGroups() [][]command {
 	cs := make([]command, len(q.commands))
 	copy(cs, q.commands)