reorganized source, added test cases for tuning

Makefile

@@ -1,97 +1,4 @@
-# Copyright © 2024 Thomas von Dein
+.PHONY: all
-
+all:
-# This program is free software: you can redistribute it and/or modify
+	make -C src
-# it under the terms of the GNU General Public License as published by
+	mv src/golsky .
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-
-# You should have received a copy of the GNU General Public License
-# along with this program. If not, see <http://www.gnu.org/licenses/>.
-
-
-#
-# no need to modify anything below
-tool      = golsky
-VERSION   = $(shell grep VERSION main.go | head -1 | cut -d '"' -f2)
-archs     = darwin freebsd linux windows
-PREFIX    = /usr/local
-UID       = root
-GID       = 0
-HAVE_POD := $(shell pod2text -h 2>/dev/null)
-#TAGS      = -tags=ebitenginedebug
-
-all: buildlocal
-
-
-buildlocal:
-	go build $(TAGS) -o $(tool)
-
-install: buildlocal
-	install -d -o $(UID) -g $(GID) $(PREFIX)/bin
-	install -d -o $(UID) -g $(GID) $(PREFIX)/man/man1
-	install -o $(UID) -g $(GID) -m 555 $(tool)  $(PREFIX)/sbin/
-	install -o $(UID) -g $(GID) -m 444 $(tool).1 $(PREFIX)/man/man1/
-
-clean:
-	rm -rf $(tool) coverage.out testdata t/out
-
-test: clean
-	mkdir -p t/out
-	go test ./... $(ARGS)
-
-testlint: test lint
-
-lint:
-	golangci-lint run
-
-lint-full:
-	golangci-lint run --enable-all --exclude-use-default --disable exhaustivestruct,exhaustruct,depguard,interfacer,deadcode,golint,structcheck,scopelint,varcheck,ifshort,maligned,nosnakecase,godot,funlen,gofumpt,cyclop,noctx,gochecknoglobals,paralleltest
-
-testfuzzy: clean
-	go test -fuzz ./... $(ARGS)
-
-singletest:
-	@echo "Call like this: make singletest TEST=TestPrepareColumns ARGS=-v"
-	go test -run $(TEST) $(ARGS)
-
-cover-report:
-	go test ./... -cover -coverprofile=coverage.out
-	go tool cover -html=coverage.out
-
-goupdate:
-	go get -t -u=patch ./...
-
-buildall:
-	./mkrel.sh $(tool) $(VERSION)
-
-release: buildall
-	gh release create $(VERSION) --generate-notes releases/*
-
-show-versions: buildlocal
-	@echo "### golsky version:"
-	@./golsky -V
-
-	@echo
-	@echo "### go module versions:"
-	@go list -m all
-
-	@echo
-	@echo "### go version used for building:"
-	@grep -m 1 go go.mod
-
-# lint:
-# 	golangci-lint run -p bugs -p unused
-
-buildwasm:
-	env GOOS=js GOARCH=wasm go build -o $(tool).wasm $(LDFLAGS) .
-
-zipwasm:
-	zip -r openquell-$(SHORTVERSION).zip index.html $(tool).wasm wasm_exec.js
-
-wasm: buildwasm zipwasm
-	@ls -l $(tool)-$(SHORTVERSION).zip

src/Makefile

@@ -0,0 +1,97 @@
+# Copyright © 2024 Thomas von Dein
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+#
+# no need to modify anything below
+tool      = golsky
+VERSION   = $(shell grep VERSION main.go | head -1 | cut -d '"' -f2)
+archs     = darwin freebsd linux windows
+PREFIX    = /usr/local
+UID       = root
+GID       = 0
+HAVE_POD := $(shell pod2text -h 2>/dev/null)
+#TAGS      = -tags=ebitenginedebug
+
+all: buildlocal
+
+
+buildlocal:
+	go build $(TAGS) -o $(tool)
+
+install: buildlocal
+	install -d -o $(UID) -g $(GID) $(PREFIX)/bin
+	install -d -o $(UID) -g $(GID) $(PREFIX)/man/man1
+	install -o $(UID) -g $(GID) -m 555 $(tool)  $(PREFIX)/sbin/
+	install -o $(UID) -g $(GID) -m 444 $(tool).1 $(PREFIX)/man/man1/
+
+clean:
+	rm -rf $(tool) coverage.out testdata t/out
+
+test: clean
+	mkdir -p t/out
+	go test ./... $(ARGS)
+
+testlint: test lint
+
+lint:
+	golangci-lint run
+
+lint-full:
+	golangci-lint run --enable-all --exclude-use-default --disable exhaustivestruct,exhaustruct,depguard,interfacer,deadcode,golint,structcheck,scopelint,varcheck,ifshort,maligned,nosnakecase,godot,funlen,gofumpt,cyclop,noctx,gochecknoglobals,paralleltest
+
+testfuzzy: clean
+	go test -fuzz ./... $(ARGS)
+
+singletest:
+	@echo "Call like this: make singletest TEST=TestPrepareColumns ARGS=-v"
+	go test -run $(TEST) $(ARGS)
+
+cover-report:
+	go test ./... -cover -coverprofile=coverage.out
+	go tool cover -html=coverage.out
+
+goupdate:
+	go get -t -u=patch ./...
+
+buildall:
+	./mkrel.sh $(tool) $(VERSION)
+
+release: buildall
+	gh release create $(VERSION) --generate-notes releases/*
+
+show-versions: buildlocal
+	@echo "### golsky version:"
+	@./golsky -V
+
+	@echo
+	@echo "### go module versions:"
+	@go list -m all
+
+	@echo
+	@echo "### go version used for building:"
+	@grep -m 1 go go.mod
+
+# lint:
+# 	golangci-lint run -p bugs -p unused
+
+buildwasm:
+	env GOOS=js GOARCH=wasm go build -o $(tool).wasm $(LDFLAGS) .
+
+zipwasm:
+	zip -r openquell-$(SHORTVERSION).zip index.html $(tool).wasm wasm_exec.js
+
+wasm: buildwasm zipwasm
+	@ls -l $(tool)-$(SHORTVERSION).zip

various-tests/drawtriangles/go.mod

@@ -0,0 +1,13 @@
+module drawminimal
+
+go 1.22
+
+require (
+	github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895 // indirect
+	github.com/ebitengine/hideconsole v1.0.0 // indirect
+	github.com/ebitengine/purego v0.7.0 // indirect
+	github.com/hajimehoshi/ebiten/v2 v2.7.4 // indirect
+	github.com/jezek/xgb v1.1.1 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.20.0 // indirect
+)

various-tests/drawtriangles/go.sum

@@ -0,0 +1,14 @@
+github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895 h1:48bCqKTuD7Z0UovDfvpCn7wZ0GUZ+yosIteNDthn3FU=
+github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895/go.mod h1:XZdLv05c5hOZm3fM2NlJ92FyEZjnslcMcNRrhxs8+8M=
+github.com/ebitengine/hideconsole v1.0.0 h1:5J4U0kXF+pv/DhiXt5/lTz0eO5ogJ1iXb8Yj1yReDqE=
+github.com/ebitengine/hideconsole v1.0.0/go.mod h1:hTTBTvVYWKBuxPr7peweneWdkUwEuHuB3C1R/ielR1A=
+github.com/ebitengine/purego v0.7.0 h1:HPZpl61edMGCEW6XK2nsR6+7AnJ3unUxpTZBkkIXnMc=
+github.com/ebitengine/purego v0.7.0/go.mod h1:ah1In8AOtksoNK6yk5z1HTJeUkC1Ez4Wk2idgGslMwQ=
+github.com/hajimehoshi/ebiten/v2 v2.7.4 h1:X+heODRQ3Ie9F9QFjm24gEZqQd5FSfR9XuT2XfHwgf8=
+github.com/hajimehoshi/ebiten/v2 v2.7.4/go.mod h1:H2pHVgq29rfm5yeQ7jzWOM3VHsjo7/AyucODNLOhsVY=
+github.com/jezek/xgb v1.1.1 h1:bE/r8ZZtSv7l9gk6nU0mYx51aXrvnyb44892TwSaqS4=
+github.com/jezek/xgb v1.1.1/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFlk=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
+golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

various-tests/drawtriangles/main.go

@@ -0,0 +1,362 @@
+package main
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"log"
+	"math/rand"
+	"os"
+	"runtime/pprof"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+	"github.com/hajimehoshi/ebiten/v2/vector"
+)
+
+var (
+	blackImage    = ebiten.NewImage(3, 3)
+	blackSubImage = blackImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image)
+)
+
+type Images struct {
+	Black, White *ebiten.Image
+}
+
+type Grid struct {
+	Data                   [][]int64
+	Width, Height, Density int
+}
+
+// Create new empty grid and allocate Data according to provided dimensions
+func NewGrid(width, height, density int) *Grid {
+	grid := &Grid{
+		Height:  height,
+		Width:   width,
+		Density: density,
+		Data:    make([][]int64, height),
+	}
+
+	for y := 0; y < height; y++ {
+		grid.Data[y] = make([]int64, width)
+	}
+
+	return grid
+}
+
+// live console output of the grid
+func (grid *Grid) Dump() {
+	/*
+		cmd := exec.Command("clear")
+		cmd.Stdout = os.Stdout
+		cmd.Run()
+
+		for y := 0; y < grid.Height; y++ {
+			for x := 0; x < grid.Width; x++ {
+				if grid.Data[y][x] == 1 {
+					fmt.Print("XX")
+				} else {
+					fmt.Print("  ")
+				}
+			}
+			fmt.Println()
+		}
+	*/
+	fmt.Printf("FPS: %0.2f\n", ebiten.ActualTPS())
+}
+
+type Game struct {
+	Width, Height, Cellsize, Density int
+	ScreenWidth, ScreenHeight        int
+	Grids                            []*Grid
+	Index                            int
+	Black, White, Grey               color.RGBA
+	Tiles                            Images
+	Cache                            *ebiten.Image
+	Elapsed                          int64
+	TPG                              int64 // adjust game speed independently of TPS
+	Vertices                         []ebiten.Vertex
+	Indices                          []uint16
+	Pause, Debug                     bool
+}
+
+// fill a cell
+func FillCell(tile *ebiten.Image, cellsize int, col color.RGBA) {
+	vector.DrawFilledRect(
+		tile,
+		float32(1),
+		float32(1),
+		float32(cellsize-1),
+		float32(cellsize-1),
+		col, false,
+	)
+}
+
+func (game *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return game.ScreenWidth, game.ScreenHeight
+}
+
+func (game *Game) Init() {
+	// setup two grids, one for display, one for next state
+	grida := NewGrid(game.Width, game.Height, game.Density)
+	gridb := NewGrid(game.Width, game.Height, game.Density)
+
+	for y := 0; y < game.Height; y++ {
+		for x := 0; x < game.Width; x++ {
+			if rand.Intn(game.Density) == 1 {
+				grida.Data[y][x] = 1
+			}
+		}
+
+	}
+
+	game.Grids = []*Grid{
+		grida,
+		gridb,
+	}
+
+	// setup colors
+	game.Grey = color.RGBA{128, 128, 128, 0xff}
+	game.Black = color.RGBA{0, 0, 0, 0xff}
+	game.White = color.RGBA{200, 200, 200, 0xff}
+
+	game.Tiles.White = ebiten.NewImage(game.Cellsize, game.Cellsize)
+	game.Cache = ebiten.NewImage(game.ScreenWidth, game.ScreenHeight)
+
+	FillCell(game.Tiles.White, game.Cellsize, game.White)
+	game.Cache.Fill(game.Grey)
+
+	// draw the offscreen image
+	op := &ebiten.DrawImageOptions{}
+	for y := 0; y < game.Height; y++ {
+		for x := 0; x < game.Width; x++ {
+			op.GeoM.Reset()
+			op.GeoM.Translate(float64(x*game.Cellsize), float64(y*game.Cellsize))
+			game.Cache.DrawImage(game.Tiles.White, op)
+		}
+	}
+
+	blackSubImage.Fill(game.Black)
+
+	lenvertices := game.ScreenHeight * game.ScreenWidth
+	game.Vertices = make([]ebiten.Vertex, lenvertices)
+	game.Indices = make([]uint16, lenvertices+(lenvertices/2))
+}
+
+// count the living neighbors of a cell
+func (game *Game) CountNeighbors(x, y int) int64 {
+	var sum int64
+
+	for nbgX := -1; nbgX < 2; nbgX++ {
+		for nbgY := -1; nbgY < 2; nbgY++ {
+			var col, row int
+
+			// Wrap  mode we look  at all the 8  neighbors surrounding
+			//  us.  In  case we  are  on an  edge we'll  look at  the
+			// neighbor on  the other side of the  grid, thus wrapping
+			// lookahead around using the mod() function.
+			col = (x + nbgX + game.Width) % game.Width
+			row = (y + nbgY + game.Height) % game.Height
+
+			sum += game.Grids[game.Index].Data[row][col]
+		}
+	}
+
+	// don't count ourselfes though
+	sum -= game.Grids[game.Index].Data[y][x]
+
+	return sum
+}
+
+// the heart of the game
+func (game *Game) CheckRule(state int64, neighbors int64) int64 {
+	var nextstate int64
+
+	if state == 0 && neighbors == 3 {
+		nextstate = 1
+	} else if state == 1 && (neighbors == 2 || neighbors == 3) {
+		nextstate = 1
+	} else {
+		nextstate = 0
+	}
+
+	return nextstate
+}
+
+// we only  update the cells if  we are not  in pause state or  if the
+// game timer (TPG) is elapsed.
+func (game *Game) UpdateCells() {
+	if game.Pause {
+		return
+	}
+
+	if game.Elapsed < game.TPG {
+		game.Elapsed++
+		return
+	}
+
+	// next grid index. we only have to, so we just xor it
+	next := game.Index ^ 1
+
+	// reset vertices
+	// FIXME: fails!
+	game.ClearVertices()
+
+	// calculate cell life state, this is the actual game of life
+	for y := 0; y < game.Height; y++ {
+		for x := 0; x < game.Width; x++ {
+			state := game.Grids[game.Index].Data[y][x] // 0|1 == dead or alive
+			neighbors := game.CountNeighbors(x, y)     // alive neighbor count
+
+			// actually apply the current rules
+			nextstate := game.CheckRule(state, neighbors)
+
+			// change state of current cell in next grid
+			game.Grids[next].Data[y][x] = nextstate
+		}
+	}
+
+	// calculate triangles for rendering
+	game.UpdateTriangles()
+
+	// switch grid for rendering
+	game.Index ^= 1
+
+	game.Elapsed = 0
+
+	if game.Debug {
+		game.Grids[next].Dump()
+	}
+}
+
+func (game *Game) Update() error {
+	game.UpdateCells()
+
+	if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
+		game.Pause = !game.Pause
+	}
+
+	return nil
+}
+
+func (game *Game) ClearVertices() {
+	// FIXME: fails
+	for i := 0; i < len(game.Vertices); i++ {
+		game.Vertices[i] = ebiten.Vertex{}
+		// game.Vertices[i].DstX = 0
+		// game.Vertices[i].DstY = 1
+	}
+
+	game.Indices = game.Indices[:len(game.Indices)]
+}
+
+// create the triangles needed for rendering. Actual rendering doesn't
+// happen here but in Draw()
+func (game *Game) UpdateTriangles() {
+	var base uint16 = 0
+	var index uint16 = 0
+
+	idx := 0
+
+	// iterate over every cell
+	for celly := 0; celly < game.Height; celly++ {
+		for cellx := 0; cellx < game.Width; cellx++ {
+
+			// if the cell is alife
+			if game.Grids[game.Index].Data[celly][cellx] == 1 {
+
+				/* iterate over the cell's corners:
+				0   1
+
+				2   3
+				*/
+				for i := 0; i < 2; i++ {
+					for j := 0; j < 2; j++ {
+
+						// calculate the corner position
+						x := (cellx * game.Cellsize) + (i * game.Cellsize) + 1
+						y := (celly * game.Cellsize) + (j * game.Cellsize) + 1
+
+						if i == 1 {
+							x -= 1
+						}
+						if j == 1 {
+							y -= 1
+						}
+
+						// setup the vertex
+						game.Vertices[idx].DstX = float32(x)
+						game.Vertices[idx].DstY = float32(y)
+						game.Vertices[idx].SrcX = 1
+						game.Vertices[idx].SrcY = 1
+						game.Vertices[idx].ColorR = float32(game.Black.R)
+						game.Vertices[idx].ColorG = float32(game.Black.G)
+						game.Vertices[idx].ColorB = float32(game.Black.B)
+						game.Vertices[idx].ColorA = 1
+
+						idx++
+					}
+				}
+			}
+
+			// indices for first triangle
+			game.Indices[index] = base
+			game.Indices[index+1] = base + 1
+			game.Indices[index+2] = base + 3
+
+			// for the second one
+			game.Indices[index+3] = base
+			game.Indices[index+4] = base + 2
+			game.Indices[index+5] = base + 3
+
+			index += 6 // 3 indicies per triangle
+
+			base += 4 // 4 vertices per cell
+		}
+	}
+}
+
+func (game *Game) Draw(screen *ebiten.Image) {
+	op := &ebiten.DrawImageOptions{}
+
+	op.GeoM.Translate(0, 0)
+	screen.DrawImage(game.Cache, op)
+
+	triop := &ebiten.DrawTrianglesOptions{}
+	screen.DrawTriangles(game.Vertices, game.Indices, blackSubImage, triop)
+}
+
+func main() {
+	size := 200
+
+	game := &Game{
+		Width:    size,
+		Height:   size,
+		Cellsize: 4,
+		Density:  5,
+		TPG:      5,
+		Debug:    true,
+	}
+
+	game.ScreenWidth = game.Width * game.Cellsize
+	game.ScreenHeight = game.Height * game.Cellsize
+
+	game.Init()
+
+	ebiten.SetWindowSize(game.ScreenWidth, game.ScreenHeight)
+	ebiten.SetWindowTitle("triangle conway's game of life")
+	ebiten.SetWindowResizingMode(ebiten.WindowResizingModeEnabled)
+
+	fd, err := os.Create("cpu.profile")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer fd.Close()
+
+	pprof.StartCPUProfile(fd)
+	defer pprof.StopCPUProfile()
+
+	if err := ebiten.RunGame(game); err != nil {
+		log.Fatal(err)
+	}
+}

various-tests/writepixel/go.mod

@@ -0,0 +1,13 @@
+module testgol
+
+go 1.22
+
+require (
+	github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895 // indirect
+	github.com/ebitengine/hideconsole v1.0.0 // indirect
+	github.com/ebitengine/purego v0.7.0 // indirect
+	github.com/hajimehoshi/ebiten/v2 v2.7.4 // indirect
+	github.com/jezek/xgb v1.1.1 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	golang.org/x/sys v0.20.0 // indirect
+)

various-tests/writepixel/go.sum

@@ -0,0 +1,14 @@
+github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895 h1:48bCqKTuD7Z0UovDfvpCn7wZ0GUZ+yosIteNDthn3FU=
+github.com/ebitengine/gomobile v0.0.0-20240518074828-e86332849895/go.mod h1:XZdLv05c5hOZm3fM2NlJ92FyEZjnslcMcNRrhxs8+8M=
+github.com/ebitengine/hideconsole v1.0.0 h1:5J4U0kXF+pv/DhiXt5/lTz0eO5ogJ1iXb8Yj1yReDqE=
+github.com/ebitengine/hideconsole v1.0.0/go.mod h1:hTTBTvVYWKBuxPr7peweneWdkUwEuHuB3C1R/ielR1A=
+github.com/ebitengine/purego v0.7.0 h1:HPZpl61edMGCEW6XK2nsR6+7AnJ3unUxpTZBkkIXnMc=
+github.com/ebitengine/purego v0.7.0/go.mod h1:ah1In8AOtksoNK6yk5z1HTJeUkC1Ez4Wk2idgGslMwQ=
+github.com/hajimehoshi/ebiten/v2 v2.7.4 h1:X+heODRQ3Ie9F9QFjm24gEZqQd5FSfR9XuT2XfHwgf8=
+github.com/hajimehoshi/ebiten/v2 v2.7.4/go.mod h1:H2pHVgq29rfm5yeQ7jzWOM3VHsjo7/AyucODNLOhsVY=
+github.com/jezek/xgb v1.1.1 h1:bE/r8ZZtSv7l9gk6nU0mYx51aXrvnyb44892TwSaqS4=
+github.com/jezek/xgb v1.1.1/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFlk=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
+golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

various-tests/writepixel/main.go

@@ -0,0 +1,294 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"os"
+	"os/exec"
+	"runtime/pprof"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+type Images struct {
+	Black, White *ebiten.Image
+}
+
+type Grid struct {
+	Data                   [][]int64
+	Width, Height, Density int
+}
+
+// Create new empty grid and allocate Data according to provided dimensions
+func NewGrid(width, height, density int) *Grid {
+	grid := &Grid{
+		Height:  height,
+		Width:   width,
+		Density: density,
+		Data:    make([][]int64, height),
+	}
+
+	for y := 0; y < height; y++ {
+		grid.Data[y] = make([]int64, width)
+	}
+
+	return grid
+}
+
+type Game struct {
+	Width, Height, Cellsize, Density int
+	ScreenWidth, ScreenHeight        int
+	Grids                            []*Grid
+	Index                            int
+	Elapsed                          int64
+	TPG                              int64 // adjust game speed independently of TPS
+	Pause, Debug, Profile, Gridlines bool
+	Pixels                           []byte
+	OffScreen                        *ebiten.Image
+}
+
+func (game *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return game.ScreenWidth, game.ScreenHeight
+}
+
+// live console output of the grid
+func (game *Game) DebugDump() {
+	cmd := exec.Command("clear")
+	cmd.Stdout = os.Stdout
+	cmd.Run()
+
+	if game.Debug {
+		for y := 0; y < game.Height; y++ {
+			for x := 0; x < game.Width; x++ {
+				if game.Grids[game.Index].Data[y][x] == 1 {
+					fmt.Print("XX")
+				} else {
+					fmt.Print("  ")
+				}
+			}
+			fmt.Println()
+		}
+	}
+	fmt.Printf("FPS: %0.2f\n", ebiten.ActualTPS())
+}
+
+func (game *Game) Init() {
+	// setup two grids, one for display, one for next state
+	grida := NewGrid(game.Width, game.Height, game.Density)
+	gridb := NewGrid(game.Width, game.Height, game.Density)
+
+	for y := 0; y < game.Height; y++ {
+		for x := 0; x < game.Width; x++ {
+			if rand.Intn(game.Density) == 1 {
+				grida.Data[y][x] = 1
+			}
+		}
+
+	}
+
+	game.Grids = []*Grid{
+		grida,
+		gridb,
+	}
+
+	game.Pixels = make([]byte, game.ScreenWidth*game.ScreenHeight*4)
+
+	game.OffScreen = ebiten.NewImage(game.ScreenWidth, game.ScreenHeight)
+}
+
+// count the living neighbors of a cell
+func (game *Game) CountNeighbors(x, y int) int64 {
+	var sum int64
+
+	for nbgX := -1; nbgX < 2; nbgX++ {
+		for nbgY := -1; nbgY < 2; nbgY++ {
+			var col, row int
+
+			// Wrap  mode we look  at all the 8  neighbors surrounding
+			//  us.  In  case we  are  on an  edge we'll  look at  the
+			// neighbor on  the other side of the  grid, thus wrapping
+			// lookahead around using the mod() function.
+			col = (x + nbgX + game.Width) % game.Width
+			row = (y + nbgY + game.Height) % game.Height
+
+			sum += game.Grids[game.Index].Data[row][col]
+		}
+	}
+
+	// don't count ourselfes though
+	sum -= game.Grids[game.Index].Data[y][x]
+
+	return sum
+}
+
+// the heart of the game
+func (game *Game) CheckRule(state int64, neighbors int64) int64 {
+	var nextstate int64
+
+	if state == 0 && neighbors == 3 {
+		nextstate = 1
+	} else if state == 1 && (neighbors == 2 || neighbors == 3) {
+		nextstate = 1
+	} else {
+		nextstate = 0
+	}
+
+	return nextstate
+}
+
+// we only  update the cells if  we are not  in pause state or  if the
+// game timer (TPG) is elapsed.
+func (game *Game) UpdateCells() {
+	if game.Pause {
+		return
+	}
+
+	if game.Elapsed < game.TPG {
+		game.Elapsed++
+		return
+	}
+
+	// next grid index. we only have to, so we just xor it
+	next := game.Index ^ 1
+
+	// calculate cell life state, this is the actual game of life
+	for y := 0; y < game.Height; y++ {
+		for x := 0; x < game.Width; x++ {
+			state := game.Grids[game.Index].Data[y][x] // 0|1 == dead or alive
+			neighbors := game.CountNeighbors(x, y)     // alive neighbor count
+
+			// actually apply the current rules
+			nextstate := game.CheckRule(state, neighbors)
+
+			// change state of current cell in next grid
+			game.Grids[next].Data[y][x] = nextstate
+		}
+	}
+
+	// switch grid for rendering
+	game.Index ^= 1
+
+	game.Elapsed = 0
+
+	game.UpdatePixels()
+}
+
+func (game *Game) Update() error {
+	game.UpdateCells()
+
+	if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
+		game.Pause = !game.Pause
+	}
+
+	return nil
+}
+
+/*
+*
+r, g, b := color(it)
+
+	78             p := 4 * (i + j*screenWidth)
+	79             gm.offscreenPix[p] = r
+	80             gm.offscreenPix[p+1] = g
+	81             gm.offscreenPix[p+2] = b
+	82             gm.offscreenPix[p+3] = 0xff
+*/
+func (game *Game) UpdatePixels() {
+	var col byte
+
+	gridx := 0
+	gridy := 0
+	idx := 0
+
+	for y := 0; y < game.ScreenHeight; y++ {
+		for x := 0; x < game.ScreenWidth; x++ {
+			gridx = x / game.Cellsize
+			gridy = y / game.Cellsize
+
+			col = 0xff
+			if game.Grids[game.Index].Data[gridy][gridx] == 1 {
+				col = 0x0
+			}
+
+			if game.Gridlines {
+				if x%game.Cellsize == 0 || y%game.Cellsize == 0 {
+					col = 128
+				}
+			}
+
+			idx = 4 * (x + y*game.ScreenWidth)
+
+			game.Pixels[idx] = col
+			game.Pixels[idx+1] = col
+			game.Pixels[idx+2] = col
+			game.Pixels[idx+3] = 0xff
+
+			idx++
+		}
+	}
+
+	game.OffScreen.WritePixels(game.Pixels)
+}
+
+func (game *Game) Draw(screen *ebiten.Image) {
+	screen.DrawImage(game.OffScreen, nil)
+	game.DebugDump()
+}
+
+func main() {
+	//x := 1
+	//y := 0
+	col := 1 >> 0xff
+
+	fmt.Printf("col: %d\n", col)
+
+	x := 1
+	y := 2
+	c := 4
+
+	xm := x & (c - 1)
+	ym := y & (c - 1)
+
+	fmt.Println(xm & ym)
+}
+
+func _main() {
+	size := 800
+
+	game := &Game{
+		Width:     size,
+		Height:    size,
+		Cellsize:  4,
+		Density:   8,
+		TPG:       10,
+		Debug:     false,
+		Profile:   false,
+		Gridlines: false,
+	}
+
+	game.ScreenWidth = game.Width * game.Cellsize
+	game.ScreenHeight = game.Height * game.Cellsize
+
+	game.Init()
+
+	ebiten.SetWindowSize(game.ScreenWidth, game.ScreenHeight)
+	ebiten.SetWindowTitle("triangle conway's game of life")
+	ebiten.SetWindowResizingMode(ebiten.WindowResizingModeEnabled)
+
+	if game.Profile {
+		fd, err := os.Create("cpu.profile")
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer fd.Close()
+
+		pprof.StartCPUProfile(fd)
+		defer pprof.StopCPUProfile()
+	}
+
+	if err := ebiten.RunGame(game); err != nil {
+		log.Fatal(err)
+	}
+}