diff --git a/field.go b/field.go
index 1277f4d..a6b6bef 100644
--- a/field.go
+++ b/field.go
@@ -19,16 +19,16 @@ type ScaleField struct {
 }
 
 func (f *ScaleField) Get(x, y float32) float32 {
-	return f.field.Get(x / f.scale, y / f.scale)
+	return f.field.Get(x/f.scale, y/f.scale)
 }
 
 type TranslateField struct {
 	field Field
-	x, y float32
+	x, y  float32
 }
 
 func (f *TranslateField) Get(x, y float32) float32 {
-	return f.field.Get(x + f.x, y + f.y)
+	return f.field.Get(x+f.x, y+f.y)
 }
 
 // NOISE FIELDS
@@ -44,13 +44,13 @@ func (f *SimplexNoiseField) Get(x, y float32) float32 {
 // IMAGE FIELDS
 
 type ImageField struct {
-	image *rl.Image
-	pixels ImagePixels
+	image            *rl.Image
+	pixels           ImagePixels
 	offsetX, offsetY float32
 }
 
 type ImagePixels struct {
-	w, h int
+	w, h   int
 	colors []rl.Color
 }
 
@@ -61,22 +61,22 @@ func (p *ImagePixels) Get(x, y int) rl.Color {
 	if y < 0 || y >= p.h {
 		return rl.Black
 	}
-	return p.colors[x + y * p.w]
+	return p.colors[x+y*p.w]
 }
 
 func NewImageField(path string) ImageField {
 	image := rl.LoadImage(path)
 	colors := rl.LoadImageColors(image)
-	pixels := ImagePixels {
-		w: int(image.Width),
-		h: int(image.Height),
+	pixels := ImagePixels{
+		w:      int(image.Width),
+		h:      int(image.Height),
 		colors: colors,
 	}
 	offsetX := float32(image.Width / 2)
 	offsetY := float32(image.Height / 2)
-	return ImageField {
-		image: image,
-		pixels: pixels,
+	return ImageField{
+		image:   image,
+		pixels:  pixels,
 		offsetX: offsetX,
 		offsetY: offsetY,
 	}
@@ -84,6 +84,6 @@ func NewImageField(path string) ImageField {
 
 func (f *ImageField) Get(x, y float32) float32 {
 	// todo : blend colors
-	c := f.pixels.Get(int(x+f.offsetX), int(y + f.offsetY))
+	c := f.pixels.Get(int(x+f.offsetX), int(y+f.offsetY))
 	return Brightness(c)
 }
diff --git a/main.go b/main.go
index bfd6cc2..77a84e0 100644
--- a/main.go
+++ b/main.go
@@ -13,12 +13,48 @@ import (
 )
 
 const (
-	screenWidth  = 3000
-	screenHeight = 2000
+	screenWidth  = 800
+	screenHeight = 600
+	sourceWidth  = 10000
+	sourceHeight = 10000
 	displayScale = 2
 	snapshotsDir = "snapshots"
 )
 
+func main3() {
+	rl.InitWindow(800, 600, "rt test")
+	defer rl.CloseWindow()
+
+	rt := rl.LoadRenderTexture(512, 512)
+	defer rl.UnloadRenderTexture(rt)
+
+	for !rl.WindowShouldClose() {
+		// draw into offscreen buffer
+		rl.BeginTextureMode(rt)
+		rl.ClearBackground(rl.Blank)
+		rl.DrawCircle(256, 256, 100, rl.Red)
+		rl.EndTextureMode()
+
+		// draw to screen
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.RayWhite)
+
+		src := rl.Rectangle{
+			X: 0, Y: 0,
+			Width:  float32(rt.Texture.Width),
+			Height: -float32(rt.Texture.Height),
+		}
+		dst := rl.Rectangle{
+			X: 0, Y: 0,
+			Width:  800,
+			Height: 600,
+		}
+
+		rl.DrawTexturePro(rt.Texture, src, dst, rl.Vector2{}, 0, rl.White)
+		rl.EndDrawing()
+	}
+}
+
 func main() {
 
 	os.MkdirAll(snapshotsDir, 0755)
@@ -47,32 +83,29 @@ func main() {
 	}
 
 	/*
-	field :=
-		ScaleField {
-			Scale: 50.0,
-			Field: &SimplexNoiseField {
-				Noise: opensimplex.NewNormalized32(0),
-			},
-		}
+			field :=
+				ScaleField {
+					Scale: 50.0,
+					Field: &SimplexNoiseField {
+						Noise: opensimplex.NewNormalized32(0),
+					},
+				}
+
+		imgf := NewImageField("/home/d/Dropbox/art/passage/data/david.png")
+
+		imageField :=
+			ScaleField{
+				field: &imgf,
+				scale: 0.5,
+			}
 	*/
 
-	imgf := NewImageField("/home/d/Dropbox/art/passage/data/david.png")
-	imageField :=
-		ScaleField {
-			field: &imgf,
-			scale: 0.5,
-		}
+	//rng := rand.New(rand.NewSource(0))
 
-	rng := rand.New(rand.NewSource(0))
+	//contourSketch := NewContourLayer(rng, &imageField)
 
-	contourSketch := NewContourLayer(rng, &imageField)
-
-	sketch := Sketch {
-		layers: []Layer {
-			&contourSketch,
-			//&FieldSketch { Field: &imageField },
-		},
-	}
+	sketch := NewSketch()
+	sketch.CreateLayer("testPattern", &TestPattern{}, sourceWidth, sourceHeight)
 
 	rl.SetTargetFPS(60)
 
@@ -90,30 +123,33 @@ func main() {
 		updateCamera(&camera)
 
 		// begin drawing
-		rl.BeginDrawing()
-		//rl.ClearBackground(rl.Black)
-		rl.BeginMode2D(camera)
-		rl.BeginBlendMode(rl.BlendAdditive)
 		t := time.Since(t0).Seconds()
 
 		// set up RenderCtx
 		renderCtx := &RenderCtx{
-			Width:  int32(w),
-			Height: int32(h),
-			Time:   t,
-			Ports:  ports.Eval(t),
-			Cam:    camera,
+			TargetWidth:  int32(w),
+			TargetHeight: int32(h),
+			SourceWidth:  int32(sourceWidth),
+			SourceHeight: int32(sourceHeight),
+			Time:         t,
+			Ports:        ports.Eval(t),
+			Cam:          camera,
 		}
 
 		/**
 		MAIN DRAWING
 		 **/
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.Blank)
 
-		rl.PushMatrix()
+		//rl.PushMatrix()
 		sketch.Draw(renderCtx)
-		rl.PopMatrix()
 
-		rl.DrawCircle(0, 0, 10, rl.Green)
+		rl.DrawText("Mouse right button drag to move, mouse wheel to zoom", 10, 10, 20, rl.White)
+		//rl.PopMatrix()
+
+		rl.EndDrawing()
+		//rl.DrawCircle(0, 0, 10, rl.Green)
 
 		if rl.IsKeyDown(rl.KeySpace) {
 			if _, err := storage.Save(); err != nil {
@@ -121,12 +157,9 @@ func main() {
 			}
 		}
 
-		rl.EndBlendMode()
-		rl.EndMode2D()
+		//rl.EndMode2D()
 
 		// HUD
-		rl.DrawText("Mouse right button drag to move, mouse wheel to zoom", 10, 10, 20, rl.Black)
-		rl.EndDrawing()
 	}
 
 	rl.CloseWindow()
@@ -138,9 +171,9 @@ type FieldSketch struct {
 
 func (s *FieldSketch) Draw(ctx *RenderCtx) {
 	fmt.Printf("drawing field")
-	for x := range ctx.Width {
-		for y := range ctx.Height {
-			screen := rl.Vector2 { X: float32(x), Y: float32(y) }
+	for x := range ctx.TargetWidth {
+		for y := range ctx.TargetHeight {
+			screen := rl.Vector2{X: float32(x), Y: float32(y)}
 			world := rl.GetScreenToWorld2D(screen, ctx.Cam)
 			v := s.Field.Get(world.X, world.Y)
 			clr := GrayCurve(v, 1.0)
@@ -150,7 +183,7 @@ func (s *FieldSketch) Draw(ctx *RenderCtx) {
 }
 
 type ContourLayer struct {
-	field Field
+	field  Field
 	actors []*Actor
 }
 
@@ -158,16 +191,16 @@ func NewContourLayer(rng *rand.Rand, field Field) ContourLayer {
 
 	actors := make([]*Actor, 20000)
 	for i := range len(actors) {
-		actors[i] = 
-			&Actor {
+		actors[i] =
+			&Actor{
 				position: RandRadialVec(rng, 0, 500, 0, 360),
-				field: field,
+				field:    field,
 				stepSize: 1,
-				color: rl.NewColor(11, 35, 176, 100),
+				color:    rl.NewColor(11, 35, 176, 100),
 			}
 	}
 
-	return ContourLayer {
+	return ContourLayer{
 		actors: actors,
 	}
 }
@@ -178,29 +211,27 @@ func (s *ContourLayer) Draw(ctx *RenderCtx) {
 	}
 }
 
-
 type Actor struct {
 	position rl.Vector2
-	field Field
+	field    Field
 	stepSize float32
-	color rl.Color
+	color    rl.Color
 }
 
 func (a *Actor) Draw() {
 	v := a.field.Get(a.position.X, a.position.Y)
-	rad := rl.Remap(v, 0, 1, 0, 3 * math.Pi)
-	nextPosition := rl.Vector2 { X: a.position.X + a.stepSize*float32(math.Cos(float64(rad))), Y: a.position.Y + a.stepSize*float32(math.Sin(float64(rad))) }
+	rad := rl.Remap(v, 0, 1, 0, 3*math.Pi)
+	nextPosition := rl.Vector2{X: a.position.X + a.stepSize*float32(math.Cos(float64(rad))), Y: a.position.Y + a.stepSize*float32(math.Sin(float64(rad)))}
 	rl.DrawLineV(a.position, nextPosition, a.color)
 	//fmt.Printf("position %v -> nextPosition %v \n", a.position, nextPosition)
 	a.position = nextPosition
 }
 
-
 func RandRadialVec(rng *rand.Rand, minRadius float32, maxRadius float32, loAngle float32, hiAngle float32) rl.Vector2 {
 	r := float64(rl.Remap(rng.Float32(), 0, 1, minRadius, maxRadius))
 	deg := float64(rl.Remap(rng.Float32(), 0, 1, loAngle, hiAngle))
 	rad := rl.Deg2rad * deg
-	return rl.Vector2 { X: float32(r * math.Cos(rad)), Y: float32(r * math.Sin(rad)) }
+	return rl.Vector2{X: float32(r * math.Cos(rad)), Y: float32(r * math.Sin(rad))}
 }
 
 func updateCamera(camera *rl.Camera2D) {
@@ -237,11 +268,11 @@ func updateCamera(camera *rl.Camera2D) {
 }
 
 type Worm struct {
-	position rl.Vector2
-	angles []float32
+	position   rl.Vector2
+	angles     []float32
 	angleIndex int
-	stepSize int
-	renderPct float32
+	stepSize   int
+	renderPct  float32
 }
 
 func (w *Worm) Draw(ctx *RenderCtx) {
@@ -256,7 +287,7 @@ func (w *Worm) Draw(ctx *RenderCtx) {
 		deltaAngle := angle - lastAngle
 		if !nudged {
 			rad := float64(deltaAngle * math.Pi / 180.0)
-			nudge := rl.Vector2 { X: float32(w.stepSize) * float32(math.Cos(rad)), Y: float32(w.stepSize) * float32(math.Sin(rad)) }
+			nudge := rl.Vector2{X: float32(w.stepSize) * float32(math.Cos(rad)), Y: float32(w.stepSize) * float32(math.Sin(rad))}
 			w.position = rl.Vector2Add(w.position, nudge)
 			nudged = true
 		}
diff --git a/sketch.go b/sketch.go
index 2d985f1..4423b67 100644
--- a/sketch.go
+++ b/sketch.go
@@ -5,21 +5,75 @@ import (
 )
 
 type Sketch struct {
-	layers []Layer
+	layerTools map[string]LayerTools
 }
 
-func (s *Sketch) Draw(ctx *RenderCtx) {
-	for _, layer := range s.layers {
-		layer.Draw(ctx)
+func NewSketch() Sketch {
+	return Sketch {
+		layerTools: make(map[string]LayerTools),
 	}
 }
 
+func (s *Sketch) CreateLayer(name string, layer Layer, sourceWidth int32, sourceHeight int32) {
+	texture := rl.LoadRenderTexture(sourceWidth, sourceHeight)
+	s.layerTools[name] = LayerTools {
+		name: name,
+		texture: &texture,
+		layer: layer,
+	}
+}
 
+func (s *Sketch) Draw(ctx *RenderCtx) {
+	// render onto all layer textures
+	for _, instance := range s.layerTools {
+		layer := instance.layer
+		rl.BeginTextureMode(*instance.texture)
+		layer.Draw(ctx)
+		rl.EndTextureMode()
+	}
+	// composite all layers to screen
+
+	src := rl.Rectangle {
+		X: 0, Y: 0,
+		Width: float32(ctx.SourceWidth),
+		Height: -float32(ctx.SourceHeight),
+	}
+	dst := rl.Rectangle {
+		X: 0, Y: 0,
+		Width: float32(ctx.TargetWidth),
+		Height: float32(ctx.TargetHeight),
+	}
+
+	for _, instance := range s.layerTools {
+		rl.DrawTexturePro(instance.texture.Texture, src, dst, rl.Vector2{}, 0, rl.White)
+	}
+	
+}
+
+type LayerTools struct {
+	name string
+	layer Layer
+	texture *rl.RenderTexture2D
+}
+
+
+/** Layer **/
 
 type Layer interface {
 	Draw(ctx *RenderCtx)
 }
 
+type TestPattern struct { }
+
+func (tp *TestPattern) Draw(ctx *RenderCtx) {
+	rl.DrawRectangle(0, 0, int32(ctx.SourceWidth), int32(ctx.SourceHeight), rl.Magenta)
+	rl.PushMatrix()
+	rl.Translatef(float32(ctx.SourceWidth)/2.0, float32(ctx.SourceHeight)/2.0, 0.0)
+	rl.DrawRectangle(-100, -100, 200, 200, rl.Green)
+	rl.PopMatrix()
+}
+
+
 /** Ports **/
 
 type Ports map[string]Signal
@@ -42,8 +96,10 @@ func (p Ports) Eval(t float64) map[string]float64 {
 /** RenderCtx **/
 
 type RenderCtx struct {
-	Width  int32
-	Height int32
+	TargetWidth  int32
+	TargetHeight int32
+	SourceWidth int32
+	SourceHeight int32
 	Time   float64
 	Ports  map[string]float64
 	Cam    rl.Camera2D
diff --git a/utils.go b/utils.go
index 6321248..ef2c340 100644
--- a/utils.go
+++ b/utils.go
@@ -1,8 +1,8 @@
 package main
 
 import (
-	"math"
 	"github.com/gen2brain/raylib-go/raylib"
+	"math"
 )
 
 func clamp01(v float32) float32 {
@@ -27,4 +27,3 @@ func Brightness(c rl.Color) float32 {
 	b := float32(c.B) / 255
 	return 0.2126*r + 0.7152*g + 0.0722*b
 }
-