branchless experiments (failed and reverted, see commented code)

src/play.go

@@ -133,9 +133,13 @@ func (scene *ScenePlay) UpdateCells() {
 			// 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
+			// 60FPS:
 			if state != nextstate {
 				scene.History.Data[y][x] = scene.Generations
 			}
+
+			// 10FPS:
+			//scene.History.Data[y][x] = (state ^ (1 ^ nextstate)) * (scene.Generations - scene.History.Data[y][x])
 		}
 	}
 
@@ -446,7 +450,8 @@ func (scene *ScenePlay) Draw(screen *ebiten.Image) {
 				float64(y*scene.Config.Cellsize),
 			)
 
-			age = scene.Generations - scene.History.Data[y][x]
+			//age = scene.Generations - scene.History.Data[y][x]
+			age = scene.History.Data[y][x]
 
 			switch scene.Grids[scene.Index].Data[y][x] {
 			case Alive:

various-tests/writepixel/main.go

@@ -252,6 +252,17 @@ func main() {
 	ym := y & (c - 1)
 
 	fmt.Println(xm & ym)
+
+	a := 1
+	b := 1
+	//gen := 100
+	hist := 0
+	for gen := 0; gen < 50; gen++ {
+		fmt.Println((a ^ (1 ^ b)) * (gen - hist))
+		if gen == 25 {
+			a = 0
+		}
+	}
 }
 
 func _main() {