attemt to speed up using writepixels

src/play.go

@@ -48,6 +48,8 @@ type ScenePlay struct {
 	Mark, Point                                image.Point   // area to marks+save
 	RunOneStep                                 bool          // mutable flags from config
 	TPG                                        int
+	Pixels                                     []byte
+	PixelColor                                 []byte
 }
 
 func NewPlayScene(game *Game, config *Config) Scene {
@@ -130,6 +132,7 @@ func (scene *ScenePlay) UpdateCells() {
 			// change state of current cell in next grid
 			scene.Grids[next].Data[y][x] = nextstate
 
+			if scene.Config.ShowEvolution {
 				// set history  to current generation so we  can infer the
 				// age of the cell's state  during rendering and use it to
 				// deduce the color to use if evolution tracing is enabled
@@ -138,6 +141,7 @@ func (scene *ScenePlay) UpdateCells() {
 				}
 			}
 		}
+	}
 
 	// switch grid for rendering
 	scene.Index ^= 1
@@ -154,6 +158,75 @@ func (scene *ScenePlay) UpdateCells() {
 	scene.TicksElapsed = 0
 }
 
+// 2: works but still too slow
+func (scene *ScenePlay) UpdatePixels() {
+	var col byte
+	width := scene.World.Bounds().Dx()
+	idx := 0
+
+	for y := 0; y < scene.Config.Height; y++ {
+		for x := 0; x < scene.Config.Width; x++ {
+			col = scene.PixelColor[scene.Grids[scene.Index].Data[y][x]]
+
+			ypx := y * scene.Config.Cellsize
+			for Y := ypx; Y < ypx+scene.Config.Cellsize; Y++ {
+				xpx := x * scene.Config.Cellsize
+				for X := xpx; X < xpx+scene.Config.Cellsize; X++ {
+					idx = 4 * (X + Y*width)
+
+					scene.Pixels[idx] = col
+					scene.Pixels[idx+1] = col
+					scene.Pixels[idx+2] = col
+					scene.Pixels[idx+3] = 0xff
+
+					idx++
+				}
+			}
+		}
+	}
+
+	scene.Cache.WritePixels(scene.Pixels)
+}
+
+// 1: works, but a little slower than 2
+func (scene *ScenePlay) _UpdatePixels() {
+	var col byte
+
+	gridx := 0
+	gridy := 0
+	idx := 0
+
+	width := scene.World.Bounds().Dx()
+	height := scene.World.Bounds().Dy()
+
+	for y := 0; y < height; y++ {
+		gridy = y / scene.Config.Cellsize // compute once per row
+
+		for x := 0; x < width; x++ {
+			gridx = x / scene.Config.Cellsize
+
+			col = scene.PixelColor[scene.Grids[scene.Index].Data[gridy][gridx]]
+
+			if scene.Config.ShowGrid {
+				if x%scene.Config.Cellsize == 0 || y%scene.Config.Cellsize == 0 {
+					col = scene.PixelColor[2]
+				}
+			}
+
+			idx = 4 * (x + y*width)
+
+			scene.Pixels[idx] = col
+			scene.Pixels[idx+1] = col
+			scene.Pixels[idx+2] = col
+			scene.Pixels[idx+3] = 0xff
+
+			idx++
+		}
+	}
+
+	scene.Cache.WritePixels(scene.Pixels)
+}
+
 func (scene *ScenePlay) Reset() {
 	scene.Config.Paused = true
 	scene.InitGrid()
@@ -433,9 +506,12 @@ func (scene *ScenePlay) Draw(screen *ebiten.Image) {
 	// a nice grey grid with grid lines
 	op := &ebiten.DrawImageOptions{}
 
+	scene.UpdatePixels()
+
 	op.GeoM.Translate(0, 0)
 	scene.World.DrawImage(scene.Cache, op)
 
+	/*
 		var age int64
 
 		for y := 0; y < scene.Config.Height; y++ {
@@ -473,7 +549,7 @@ func (scene *ScenePlay) Draw(screen *ebiten.Image) {
 				}
 			}
 		}
-
+	*/
 	scene.DrawMark(scene.World)
 
 	scene.Camera.Render(scene.World, screen)
@@ -649,6 +725,8 @@ func (scene *ScenePlay) Init() {
 		scene.Config.Height*scene.Config.Cellsize,
 	)
 
+	scene.Pixels = make([]byte, scene.World.Bounds().Dx()*scene.World.Bounds().Dy()*scene.Config.Cellsize)
+
 	scene.InitTiles()
 	scene.InitCache()
 
@@ -672,6 +750,11 @@ func (scene *ScenePlay) Init() {
 	}
 
 	scene.Camera.Setup()
+
+	scene.PixelColor = make([]byte, 3)
+	scene.PixelColor[0] = 0xff
+	scene.PixelColor[1] = 0x00
+	scene.PixelColor[2] = 0xff
 }
 
 // count the living neighbors of a cell