fixed grid lines performance problem

src/play.go

@@ -52,7 +52,7 @@ type ScenePlay struct {
 	Generations   int64         // Stats
 	TicksElapsed  int           // tick counter for game speed
 	Camera        Camera        // for zoom+move
-	World, Cache, GridImage *ebiten.Image // actual image we render to
+	World, Cache  *ebiten.Image // actual image we render to
 	WheelTurned   bool          // when user turns wheel multiple times, zoom faster
 	Dragging      bool          // middle mouse is pressed, move canvas
 	LastCursorPos []float64     // used to check if the user is dragging
@@ -505,13 +505,6 @@ func (scene *ScenePlay) Draw(screen *ebiten.Image) {
 		}
 	}
 
-	if scene.Config.ShowGrid {
-		// draw the pre-drawn grid onto the world
-		op.GeoM.Reset()
-		op.GeoM.Translate(0, 0)
-		scene.World.DrawImage(scene.GridImage, op)
-	}
-
 	scene.DrawMark(scene.World)
 
 	scene.Camera.Render(scene.World, screen)
@@ -610,22 +603,19 @@ func (scene *ScenePlay) InitPattern() {
 
 // pre-render offscreen cache image
 func (scene *ScenePlay) InitCache() {
-	op := &ebiten.DrawImageOptions{}
+	// setup theme
+	scene.Theme.SetGrid(scene.Config.ShowGrid)
 
-	if scene.Config.ShowGrid {
-		scene.Cache.Fill(scene.Theme.Color(ColGrid))
-	} else {
+	if !scene.Config.ShowGrid {
 		scene.Cache.Fill(scene.Theme.Color(ColDead))
+		return
 	}
 
-	for y := 0; y < scene.Config.Height; y++ {
-		// horizontal grid line
-		vector.StrokeLine(scene.GridImage,
-			float32(0), float32(y*scene.Config.Cellsize),
-			float32(scene.Config.Width*scene.Config.Cellsize), float32(y*scene.Config.Cellsize),
-			1, scene.Theme.Color(ColGrid), false,
-		)
+	op := &ebiten.DrawImageOptions{}
 
+	scene.Cache.Fill(scene.Theme.Color(ColGrid))
+
+	for y := 0; y < scene.Config.Height; y++ {
 		for x := 0; x < scene.Config.Width; x++ {
 			op.GeoM.Reset()
 			op.GeoM.Translate(
@@ -634,13 +624,6 @@ func (scene *ScenePlay) InitCache() {
 			)
 
 			scene.Cache.DrawImage(scene.Theme.Tile(ColDead), op)
-
-			// vertical grid line
-			vector.StrokeLine(scene.GridImage,
-				float32(x*scene.Config.Cellsize), float32(0),
-				float32(x*scene.Config.Cellsize), float32(scene.Config.Height*scene.Config.Cellsize),
-				1, scene.Theme.Color(ColGrid), false,
-			)
 		}
 	}
 }
@@ -687,11 +670,6 @@ func (scene *ScenePlay) Init() {
 		scene.Config.Height*scene.Config.Cellsize,
 	)
 
-	scene.GridImage = ebiten.NewImage(
-		scene.Config.Width*scene.Config.Cellsize,
-		scene.Config.Height*scene.Config.Cellsize,
-	)
-
 	scene.Theme = scene.Config.ThemeManager.GetCurrentTheme()
 	scene.InitCache()
 

src/theme.go

@@ -26,8 +26,10 @@ const (
 // readily available from play.go
 type Theme struct {
 	Tiles     map[int]*ebiten.Image
+	GridTiles map[int]*ebiten.Image
 	Colors    map[int]color.RGBA
 	Name      string
+	ShowGrid  bool
 }
 
 type ThemeDef struct {
@@ -84,10 +86,14 @@ func NewTheme(def ThemeDef, cellsize int, name string) Theme {
 	}
 
 	theme.Tiles = make(map[int]*ebiten.Image, 6)
+	theme.GridTiles = make(map[int]*ebiten.Image, 6)
 
 	for cid, col := range theme.Colors {
 		theme.Tiles[cid] = ebiten.NewImage(cellsize, cellsize)
-		FillCell(theme.Tiles[cid], cellsize, col)
+		FillCell(theme.Tiles[cid], cellsize, col, 0)
+
+		theme.GridTiles[cid] = ebiten.NewImage(cellsize, cellsize)
+		FillCell(theme.GridTiles[cid], cellsize, col, 1)
 	}
 
 	return theme
@@ -97,6 +103,10 @@ func NewTheme(def ThemeDef, cellsize int, name string) Theme {
 // unknown type is being used, which is ok, since the code is the only
 // user anyway
 func (theme *Theme) Tile(col int) *ebiten.Image {
+	if theme.ShowGrid {
+		return theme.GridTiles[col]
+	}
+
 	return theme.Tiles[col]
 }
 
@@ -104,6 +114,10 @@ func (theme *Theme) Color(col int) color.RGBA {
 	return theme.Colors[col]
 }
 
+func (theme *Theme) SetGrid(showgrid bool) {
+	theme.ShowGrid = showgrid
+}
+
 type ThemeManager struct {
 	Theme  string
 	Themes map[string]Theme
@@ -152,11 +166,11 @@ func (manager *ThemeManager) SetCurrentTheme(theme string) {
 //
 // So we don't draw a grid, we just left a grid behind, which saves us
 // from a lot of drawing operations.
-func FillCell(tile *ebiten.Image, cellsize int, col color.RGBA) {
+func FillCell(tile *ebiten.Image, cellsize int, col color.RGBA, x int) {
 	vector.DrawFilledRect(
 		tile,
-		float32(0),
-		float32(0),
+		float32(x),
+		float32(x),
 		float32(cellsize),
 		float32(cellsize),
 		col, false,