diff --git a/edt/edt.go b/edt/edt.go
new file mode 100644
index 0000000..db2460b
--- /dev/null
+++ b/edt/edt.go
@@ -0,0 +1,293 @@
+package edt
+
+import "math"
+
+type Bounds struct {
+	X int
+	Y int
+}
+
+type Coordinate struct {
+	X int
+	Y int
+}
+
+/*
+Represents a Euclidean Distance Transform of dimensions Dimensions with the transform
+stored in D and a lookup in L. The lookup represents the nearest occupied coordinate (x, y)
+relative to the current coordinate.
+*/
+type EDT struct {
+	Dimensions Bounds       //spatial dimensions
+	D          []float64    //distance transform
+	L          []Coordinate //transform lookup
+	gx         []float64    //buffer for our vector function, per row
+	gy         []float64    //buffer for our vector function, per column
+}
+
+func NewEDT(dimensions Bounds) *EDT {
+	edt := &EDT{
+		Dimensions: dimensions,
+	}
+
+	edt.InitializeD()
+	return edt
+}
+
+func (edt *EDT) InitializeD() {
+
+	n := edt.Dimensions.X * edt.Dimensions.Y
+	if n <= 0 {
+		return
+	}
+
+	edt.D = make([]float64, n)
+	edt.L = make([]Coordinate, n)
+	edt.gx = make([]float64, edt.Dimensions.X)
+	edt.gy = make([]float64, edt.Dimensions.Y)
+
+	for i := range n {
+		edt.D[i] = math.Inf(+1)
+	}
+}
+
+/*
+Reinitializes EDT using occupancy values. Occupancy dimensions must match EDT.
+*/
+func (edt *EDT) AssignOccupancy(occupancy []bool) {
+
+	n := edt.Dimensions.X * edt.Dimensions.Y
+	if len(occupancy) != n {
+		return
+	}
+
+	//assign occupancy values
+	for i := range n {
+		if occupancy[i] {
+			edt.D[i] = 0
+		} else {
+			edt.D[i] = math.Inf(+1)
+		}
+	}
+}
+
+/*
+EDT must already have been initialized with occupancy assigned
+*/
+func (edt *EDT) ComputeDistanceTransform() {
+	if len(edt.D) == 0 {
+		return
+	}
+	//compute edt for each row
+	for j := range edt.Dimensions.Y {
+		//prepare our row vector
+		edt.ConstructGx(j)
+
+		//compute distance transform for this row
+		//rowD, rowL := edt.DistanceTransform1D(edt.gx)
+		rowD, rowL := edt1D_with_labels(edt.gx)
+
+		//update corresponding row
+		edt.UpdateRow(j, rowD, rowL)
+	}
+
+	//compute edt for each column
+	for i := range edt.Dimensions.X {
+		//prepare our column vector
+		edt.ConstructGy(i)
+
+		//compute distance transform for this column
+		//colD, colL := edt.DistanceTransform1D(edt.gy)
+		colD, colL := edt1D_with_labels(edt.gy)
+
+		//update corresponding column
+		edt.UpdateCol(i, colD, colL)
+	}
+}
+
+/*Computes EDT and assigns lookup coordinates for given vector g*/
+func (edt *EDT) DistanceTransform1D(g []float64) (d []float64, l []int) {
+	//perform 1d distance transform
+	n := len(g)
+	d = make([]float64, n)
+	l = make([]int, n)
+
+	v := make([]int, n)
+	// envelope sites (seed indices)
+	z := make([]float64, n+1) // changeover abscissae
+	k := 0
+
+	// top
+	v[0] = 0
+	z[0] = math.Inf(-1)
+	z[1] = math.Inf(+1)
+
+	// initialize first valid seed
+	k = -1
+	for q := 0; q < n; q++ {
+		if g[q] == math.Inf(+1) {
+			continue
+		}
+
+		// push q: pop while it starts before current segment
+		var s float64
+		for {
+			if k < 0 {
+				k = 0
+				v[0] = q
+				z[0] = math.Inf(-1)
+				z[1] = math.Inf(+1)
+				break
+			}
+			i := v[k]
+			// intersection s(i,q)
+			s = ((float64(q*q) + g[q]) - (float64(i*i) + g[i])) / float64(2*(q-i))
+			if s <= z[k] {
+				k--
+				if k < 0 {
+					continue
+				} // force a push with -inf
+			} else {
+				k++
+				v[k] = q
+				z[k] = s
+				z[k+1] = math.Inf(+1)
+				break
+			}
+		}
+	}
+
+	// evaluate
+	k = 0
+	for x := 0; x < n; x++ {
+		for z[k+1] <= float64(x) {
+			k++
+		}
+		i := v[k]
+		l[x] = i
+		dx := float64(x - i)
+		d[x] = dx*dx + g[i]
+	}
+
+	return d, l
+}
+
+func edt1D_with_labels(g []float64) ([]float64, []int) {
+	n := len(g)
+	d := make([]float64, n)
+	l := make([]int, n)
+
+	// --- 1. Gather valid seeds ---
+	type site struct {
+		i  int
+		gi float64
+	}
+	seeds := make([]site, 0, n)
+	for i := 0; i < n; i++ {
+		if !math.IsInf(g[i], +1) { // it's a seed
+			seeds = append(seeds, site{i, g[i]})
+		}
+	}
+
+	// --- 2. Handle empty case directly ---
+	if len(seeds) == 0 {
+		for i := 0; i < n; i++ {
+			d[i] = math.Inf(+1)
+			l[i] = -1
+		}
+		return d, l
+	}
+
+	// --- 3. Lower-envelope construction (Felzenszwalb–Huttenlocher) ---
+	v := make([]int, len(seeds))
+	z := make([]float64, len(seeds)+1)
+	k := 0
+	v[0] = seeds[0].i
+	z[0] = math.Inf(-1)
+	z[1] = math.Inf(+1)
+
+	for q := 1; q < len(seeds); q++ {
+		i := seeds[q].i
+		gi := seeds[q].gi
+		for {
+			j := v[k]
+			gj := g[j]
+			s := ((float64(i*i) + gi) - (float64(j*j) + gj)) / float64(2*(i-j))
+			if s <= z[k] {
+				k--
+				if k < 0 {
+					k = 0
+					break
+				}
+				continue
+			}
+			k++
+			v[k] = i
+			z[k] = s
+			z[k+1] = math.Inf(+1)
+			break
+		}
+	}
+
+	// --- 4. Evaluate ---
+	k = 0
+	for x := 0; x < n; x++ {
+		for z[k+1] <= float64(x) {
+			k++
+		}
+		i := v[k]
+		l[x] = i
+		dx := float64(x - i)
+		d[x] = dx*dx + g[i]
+	}
+
+	return d, l
+}
+
+/*
+Prepares row vector (gx) from specified column in D
+*/
+func (edt *EDT) ConstructGx(col int) {
+	if col < edt.Dimensions.Y {
+		//we can be very efficient due to slice referencing
+		startIdx := col * edt.Dimensions.Y
+		edt.gx = edt.D[startIdx : startIdx+edt.Dimensions.X]
+	}
+}
+
+/*
+Prepares column vector (gy) from specified row in D
+*/
+func (edt *EDT) ConstructGy(row int) {
+	if row < edt.Dimensions.X {
+		for j := range edt.Dimensions.Y {
+			edt.gy[j] = edt.D[j*edt.Dimensions.X+row]
+		}
+	}
+}
+
+/*
+Writes data and lookup values into EDT row specified by rowidx
+*/
+func (edt *EDT) UpdateRow(rowidx int, data []float64, lookup []int) {
+	if rowidx < edt.Dimensions.Y {
+		startidx := rowidx * edt.Dimensions.X
+		for i := range edt.Dimensions.X {
+			edt.D[startidx+i] = data[i]
+			edt.L[startidx+i].X = lookup[i]
+		}
+	}
+}
+
+/*
+Writes data and lookup values into EDT column specified by colidx
+*/
+func (edt *EDT) UpdateCol(colidx int, data []float64, lookup []int) {
+	if colidx < edt.Dimensions.X {
+		for j := range edt.Dimensions.Y {
+			edt.D[j*edt.Dimensions.X+colidx] = data[j]
+			edt.L[j*edt.Dimensions.X+colidx].X = edt.L[lookup[j]*edt.Dimensions.X+colidx].X
+			edt.L[j*edt.Dimensions.X+colidx].Y = lookup[j]
+		}
+	}
+}
diff --git a/elements/flaskRoundedBottom.go b/elements/flaskRoundedBottom.go
index 5a7f413..d335456 100644
--- a/elements/flaskRoundedBottom.go
+++ b/elements/flaskRoundedBottom.go
@@ -12,6 +12,8 @@ import (
 const (
 	RoundedBottomFlaskWidth           = 32  //pixels
 	RoundedBottomFlaskHeight          = 32  //pixels
+	RBFlaskMaskWidth                  = 46  //pixels
+	RBFlaskMaskHeight                 = 46  //pixels
 	RoundedBottomFlaskFluidRadius     = 9   //pixels: represents spherical portion of the flask where fluid will be contained
 	RoundedBottomFlaskFluidOriginX    = 16  //pixels: x origin of fluid area
 	RoundedBottomFlaskFluidOriginY    = 20  //pixels: y origin of fluid area
@@ -22,27 +24,38 @@ const (
 
 type RoundedBottomFlask struct {
 	MappedEntityBase
-	fluid          *fluid.Fluid    //our physical representation of the fluid
-	fluidbuff      *ebiten.Image   //predraw for the fluid
-	fluidcellbuff  *ebiten.Image   //persistent fluid sprite, we redraw this everywhere we want to represent fluid
-	flaskbase      *ebiten.Image   //flask background (container)
-	flaskhighlight *ebiten.Image   //flask foreground (glassware highlights)
-	fieldscale     gamedata.Vector //used for transforming from fluid-space to sprite-space
-	angle          float64
+	fluid             *fluid.Fluid    //our physical representation of the fluid
+	fluidbuffS        *ebiten.Image   //predraw for the fluid, static
+	fluidbuffD        *ebiten.Image   //predraw for the fluid, dynamic
+	fluidcellbuff     *ebiten.Image   //persistent fluid sprite, we redraw this everywhere we want to represent fluid
+	flaskbase         *ebiten.Image   //flask background (container)
+	flaskhighlight    *ebiten.Image   //flask foreground (glassware highlights)
+	flaskboundarymask *ebiten.Image   //flask boundary mask
+	fieldscaleStatic  gamedata.Vector //used for transforming from fluid-space to sprite-space: static
+	fieldscaleDyanmic gamedata.Vector //used for transforming from fluid-space to sprite-space: dynamic
+	angle             float64
 
 	//fluid color business
 	fluidcolor  color.RGBA //premultiplied fluid color, as set by external sources
 	fluidcolorF []float32  //for caching of individual color values, we compute rarely
+
+	//boundary
+	boundaryinitialized bool
+	container           *fluid.Boundary
 }
 
 func NewRoundedBottomFlask() *RoundedBottomFlask {
 	flask := &RoundedBottomFlask{
-		fluidbuff:      ebiten.NewImage(RoundedBottomFlaskFluidRadius*2, RoundedBottomFlaskFluidRadius*2),
-		fluidcellbuff:  ebiten.NewImage(1, 1),
-		flaskbase:      ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskBase]),
-		flaskhighlight: ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskHighlights]),
-		angle:          0,
-		fluidcolorF:    make([]float32, 4), //one field each for R,G,B,A
+		fluidbuffS:        ebiten.NewImage(RoundedBottomFlaskFluidRadius*2, RoundedBottomFlaskFluidRadius*2),
+		fluidbuffD:        ebiten.NewImage(RBFlaskMaskWidth, RBFlaskMaskHeight),
+		fluidcellbuff:     ebiten.NewImage(1, 1),
+		flaskbase:         ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskBase]),
+		flaskhighlight:    ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskHighlights]),
+		flaskboundarymask: ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskBoundaryMap46]),
+		//flaskboundarymask:   ebiten.NewImageFromImage(resources.ImageBank[resources.RoundedBottomFlaskBoundaryMap]),
+		angle:               0,
+		fluidcolorF:         make([]float32, 4), //one field each for R,G,B,A
+		boundaryinitialized: false,
 	}
 	flask.Initialize()
 	return flask
@@ -66,17 +79,23 @@ func (flask *RoundedBottomFlask) Initialize() {
 	flask.fluid.Initialize()
 	flask.fluid.Block = false //rounded flask, not a rect volume
 
-	//compute fieldscale using newly created fluid
-	flask.fieldscale = gamedata.Vector{
+	//compute fieldscales using newly created fluid
+	flask.fieldscaleStatic = gamedata.Vector{
 		X: RoundedBottomFlaskFluidRadius * 2 / float64(flask.fluid.Field.Nx-1),
 		Y: RoundedBottomFlaskFluidRadius * 2 / float64(flask.fluid.Field.Ny-1),
 	}
 
+	flask.fieldscaleDyanmic = gamedata.Vector{
+		X: RBFlaskMaskWidth / float64(flask.fluid.Field.Nx-2),
+		Y: RBFlaskMaskHeight / float64(flask.fluid.Field.Ny-2),
+	}
+
 	//setup default fluid color
 	flask.SetFluidColor(color.RGBA{R: 0x0, G: 0x0, B: 0xff, A: 0xff})
 }
 
 func (flask *RoundedBottomFlask) Update() {
+
 	if flask.paused {
 		return
 	}
@@ -91,7 +110,11 @@ func (flask *RoundedBottomFlask) Draw() {
 	flask.Sprite.DrawImage(flask.flaskbase, nil)
 
 	//render fluid
-	flask.RenderFluid()
+	if flask.boundaryinitialized {
+		flask.RenderFluidDynamic()
+	} else {
+		flask.RenderFluidStatic()
+	}
 
 	//render flask foreground
 	flask.Sprite.DrawImage(flask.flaskhighlight, nil)
@@ -107,8 +130,10 @@ func (flask *RoundedBottomFlask) GetAngle() float64 {
 	return flask.angle
 }
 
-func (flask *RoundedBottomFlask) RenderFluid() {
-	flask.fluidbuff.Clear()
+func (flask *RoundedBottomFlask) RenderFluidDynamic() {
+	flask.fluidbuffD.Clear()
+	//flask.fluidbuffD.Fill(color.White)
+	//vector.StrokeRect(flask.fluidbuffD, 0, 0, 46, 46, 1, color.White, true)
 
 	//construct fluid buffer from fluid simulation
 	for i := range flask.fluid.Field.Nx {
@@ -125,17 +150,56 @@ func (flask *RoundedBottomFlask) RenderFluid() {
 				celldensity = 1
 			}*/
 
-			ox := float64(i) * flask.fieldscale.X
-			oy := float64(j) * flask.fieldscale.Y
+			ox := float64(i) * flask.fieldscaleDyanmic.X
+			oy := float64(j) * flask.fieldscaleDyanmic.Y
 			op := &ebiten.DrawImageOptions{}
 			op.GeoM.Translate(-.5, -.5)
-			op.GeoM.Scale(flask.fieldscale.X, flask.fieldscale.Y)
+			op.GeoM.Scale(flask.fieldscaleDyanmic.X, flask.fieldscaleDyanmic.Y)
 			op.GeoM.Translate(ox, oy)
 			op.ColorScale.ScaleAlpha(celldensity)
 			op.ColorScale.Scale(flask.fluidcolorF[0], flask.fluidcolorF[1], flask.fluidcolorF[2], flask.fluidcolorF[3])
-			//			op.ColorM.Scale(0, 0, 1, 1)
-			//flask.Sprite.DrawImage(flask.fluidcellbuff, op)
-			flask.fluidbuff.DrawImage(flask.fluidcellbuff, op)
+			flask.fluidbuffD.DrawImage(flask.fluidcellbuff, op)
+		}
+	}
+
+	//transform buffer for our flask space
+
+	s := float64(RoundedBottomFlaskWidth) / RBFlaskMaskWidth * 67. / 104
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Translate(-RBFlaskMaskWidth/2, -RBFlaskMaskHeight/2)
+	op.GeoM.Scale(s, -s*1.15)
+	op.GeoM.Translate(RoundedBottomFlaskWidth/2, RoundedBottomFlaskHeight/2+2)
+	//op.GeoM.Translate(RoundedBottomFlaskFluidOriginX, RoundedBottomFlaskFluidOriginY)
+	flask.Sprite.DrawImage(flask.fluidbuffD, op)
+}
+
+func (flask *RoundedBottomFlask) RenderFluidStatic() {
+	flask.fluidbuffS.Clear()
+
+	//construct fluid buffer from fluid simulation
+	for i := range flask.fluid.Field.Nx {
+		for j := range flask.fluid.Field.Ny {
+
+			idx := i*flask.fluid.Field.Ny + j
+
+			if flask.fluid.Field.CellType[idx] != fluid.CellTypeFluid {
+				continue
+			}
+
+			celldensity := flask.fluid.ParticleDensity[idx] / flask.fluid.ParticleRestDensity
+			/*if celldensity > 0.8 {
+				celldensity = 1
+			}*/
+
+			ox := float64(i) * flask.fieldscaleStatic.X
+			oy := float64(j) * flask.fieldscaleStatic.Y
+			op := &ebiten.DrawImageOptions{}
+			op.GeoM.Translate(-.5, -.5)
+			op.GeoM.Scale(flask.fieldscaleStatic.X, flask.fieldscaleStatic.Y)
+			op.GeoM.Translate(ox, oy)
+			op.ColorScale.ScaleAlpha(celldensity)
+			op.ColorScale.Scale(flask.fluidcolorF[0], flask.fluidcolorF[1], flask.fluidcolorF[2], flask.fluidcolorF[3])
+			flask.fluidbuffS.DrawImage(flask.fluidcellbuff, op)
 		}
 	}
 
@@ -145,7 +209,7 @@ func (flask *RoundedBottomFlask) RenderFluid() {
 	op.GeoM.Translate(-RoundedBottomFlaskFluidRadius, -RoundedBottomFlaskFluidRadius)
 	op.GeoM.Scale(1, -1)
 	op.GeoM.Translate(RoundedBottomFlaskFluidOriginX, RoundedBottomFlaskFluidOriginY)
-	flask.Sprite.DrawImage(flask.fluidbuff, op)
+	flask.Sprite.DrawImage(flask.fluidbuffS, op)
 }
 
 func (flask *RoundedBottomFlask) SetFluidColor(c color.RGBA) {
@@ -155,3 +219,47 @@ func (flask *RoundedBottomFlask) SetFluidColor(c color.RGBA) {
 	flask.fluidcolorF[2] = float32(flask.fluidcolor.B) / float32(flask.fluidcolor.A)
 	flask.fluidcolorF[3] = float32(flask.fluidcolor.A) / 0xff
 }
+
+func (flask *RoundedBottomFlask) InitializeBoundary() {
+
+	//prepare the dimensions of our boundary map
+	dimensions := fluid.BoundaryDimensions{
+		X: RBFlaskMaskWidth,
+		Y: RBFlaskMaskHeight,
+	}
+
+	//instantiate the boundary structure
+	flask.container = fluid.NewBoundary(dimensions)
+
+	//load pixel data from boundary
+	var pixels []byte = make([]byte, dimensions.X*dimensions.Y*4)
+	flask.flaskboundarymask.ReadPixels(pixels)
+
+	//populate our boundary map based on the pixel data
+	for i := 0; i < len(pixels); i += 4 {
+		cellidx := i / 4
+		boundary := pixels[i] == 0
+		flask.container.Cells[cellidx] = !boundary
+	}
+
+	//apply to fluid simulation
+	flask.fluid.SetBoundary(flask.container)
+	flask.boundaryinitialized = true
+}
+
+// set new boundary mask and reinitialize associated data, including computing and
+// passing that into the associated fluid simulation
+func (flask *RoundedBottomFlask) SetBoundaryMap(img *ebiten.Image) {
+	flask.flaskboundarymask = img
+	flask.InitializeBoundary()
+}
+
+func (flask *RoundedBottomFlask) ToggleBoundaryMask() {
+	if flask.boundaryinitialized {
+		flask.fluid.SetBoundary(nil)
+		flask.boundaryinitialized = false
+	} else {
+		flask.InitializeBoundary()
+		flask.boundaryinitialized = true
+	}
+}
diff --git a/fluid/boundary.go b/fluid/boundary.go
new file mode 100644
index 0000000..0d4269f
--- /dev/null
+++ b/fluid/boundary.go
@@ -0,0 +1,19 @@
+package fluid
+
+type BoundaryDimensions struct {
+	X int
+	Y int
+}
+
+type Boundary struct {
+	Dimensions BoundaryDimensions
+	Cells      []bool
+}
+
+func NewBoundary(dimensions BoundaryDimensions) *Boundary {
+	b := &Boundary{
+		Dimensions: dimensions,
+		Cells:      make([]bool, dimensions.X*dimensions.Y),
+	}
+	return b
+}
diff --git a/fluid/fluid.go b/fluid/fluid.go
index 9fd1179..ebe8d22 100644
--- a/fluid/fluid.go
+++ b/fluid/fluid.go
@@ -4,6 +4,7 @@
 package fluid
 
 import (
+	"fluids/edt"
 	"fluids/utils"
 	"math"
 )
@@ -41,6 +42,9 @@ type Fluid struct {
 	flipPicRatio        float32
 	numSubSteps         int  //number of simulation substeps
 	Block               bool //rectangular or circular field container
+
+	//for arbitrary boundaries
+	edt *edt.EDT
 }
 
 func NewFluid(dimensions FieldVector, spacing float32) *Fluid {
@@ -52,6 +56,7 @@ func NewFluid(dimensions FieldVector, spacing float32) *Fluid {
 		flipPicRatio:        FluidDefaultFlipPicRatio,
 		numSubSteps:         FluidDefaultSubSteps,
 		Block:               true,
+		edt:                 nil,
 	}
 
 	f.Initialize()
@@ -268,6 +273,11 @@ func (f *Fluid) HandleParticleCollisions() {
 		minDist2 := minDist * minDist
 	*/
 
+	if f.edt != nil {
+		f.HandleBoundaryCollisions()
+		return
+	}
+
 	if f.Block {
 		minX := f.Field.H + f.particleRadius
 		maxX := float32(f.Field.Nx-1)*f.Field.H - f.particleRadius
@@ -651,3 +661,53 @@ func (f *Fluid) SolveIncompressibility() {
 func (f *Fluid) ToggleShape() {
 	f.Block = !f.Block
 }
+
+func (f *Fluid) SetBoundary(b *Boundary) {
+
+	if b != nil {
+		dim := edt.Bounds{
+			X: b.Dimensions.X,
+			Y: b.Dimensions.Y,
+		}
+
+		f.edt = edt.NewEDT(dim)
+		f.edt.AssignOccupancy(b.Cells)
+		f.edt.ComputeDistanceTransform()
+	} else {
+		f.edt = nil
+	}
+}
+
+// we perform our boundary resolution on particles according to our defined fluid boundary
+func (f *Fluid) HandleBoundaryCollisions() {
+
+	//grid spacing within our distance field
+	dx := f.Field.Dimensions.X / float32(f.edt.Dimensions.X)
+	dy := f.Field.Dimensions.Y / float32(f.edt.Dimensions.Y)
+
+	//find cell of distance field for which particles belong, check if it's in bounds
+	for i := range f.Particles {
+		p := &f.Particles[i]
+
+		xi := utils.Clamp(int(math.Floor(float64(p.Position.X/dx))), 0, f.edt.Dimensions.X-1)
+		yi := utils.Clamp(int(math.Floor(float64(p.Position.Y/dy))), 0, f.edt.Dimensions.Y-1)
+
+		cellidx := xi + yi*f.edt.Dimensions.X
+
+		//if our current cell isn't a boundary, then we skip
+		if f.edt.D[cellidx] == 0 {
+			continue
+		}
+
+		//find where the particle actually belongs
+		pos := f.edt.L[cellidx]
+		newx := (float32(pos.X-xi) + f.particleRadius) * dx
+		newy := (float32(pos.Y-yi) + f.particleRadius) * dy
+		p.Position.X += newx
+		p.Position.Y += newy
+		p.Velocity.X = 0
+		p.Velocity.Y = 0
+
+	}
+
+}
diff --git a/game/game.go b/game/game.go
index 99f767f..9c30096 100644
--- a/game/game.go
+++ b/game/game.go
@@ -335,6 +335,10 @@ func (g *Game) ManageFlaskInputs() {
 
 		g.mfangle = g.mfangle + (angle - g.mdangle)
 	}
+
+	if inpututil.IsKeyJustPressed(ebiten.KeyM) {
+		g.flask.ToggleBoundaryMask()
+	}
 }
 
 func (g *Game) UpdateFlask() {
diff --git a/resources/images.go b/resources/images.go
index 1f712f9..cb8259a 100644
--- a/resources/images.go
+++ b/resources/images.go
@@ -13,8 +13,10 @@ import (
 type ImageName string
 
 const (
-	RoundedBottomFlaskBase       ImageName = "RoundedBottomFlaskBase"
-	RoundedBottomFlaskHighlights ImageName = "RoundedBottomFlaskHighlights"
+	RoundedBottomFlaskBase          ImageName = "RoundedBottomFlaskBase"
+	RoundedBottomFlaskHighlights    ImageName = "RoundedBottomFlaskHighlights"
+	RoundedBottomFlaskBoundaryMap   ImageName = "RoundedBottomFlaskBoundaryMap"
+	RoundedBottomFlaskBoundaryMap46 ImageName = "RoundedBottomFlaskBoundaryMap46"
 )
 
 var (
@@ -23,13 +25,19 @@ var (
 	//go:embed rounded_bottom_flask_base.png
 	rounded_bottom_flask_base []byte
 	//go:embed rounded_bottom_flask_highlights.png
-	rounded_bottom_flask_highlitsh []byte
+	rounded_bottom_flask_highlight []byte
+	//go:embed rounded_bottom_flask_boundary_map.png
+	rounded_bottom_flask_boundary_map []byte
+	//go:embed rounded_bottom_flask_boundary_map_46.png
+	rounded_bottom_flask_boundary_map_46 []byte
 )
 
 func LoadImages() {
 	ImageBank = make(map[ImageName]*ebiten.Image)
 	ImageBank[RoundedBottomFlaskBase] = LoadImagesFatal(rounded_bottom_flask_base)
-	ImageBank[RoundedBottomFlaskHighlights] = LoadImagesFatal(rounded_bottom_flask_highlitsh)
+	ImageBank[RoundedBottomFlaskHighlights] = LoadImagesFatal(rounded_bottom_flask_highlight)
+	ImageBank[RoundedBottomFlaskBoundaryMap] = LoadImagesFatal(rounded_bottom_flask_boundary_map)
+	ImageBank[RoundedBottomFlaskBoundaryMap46] = LoadImagesFatal(rounded_bottom_flask_boundary_map_46)
 }
 
 func LoadImagesFatal(b []byte) *ebiten.Image {
diff --git a/resources/rounded_bottom_flask_boundary_map.png b/resources/rounded_bottom_flask_boundary_map.png
new file mode 100644
index 0000000..862c6eb
Binary files /dev/null and b/resources/rounded_bottom_flask_boundary_map.png differ
diff --git a/resources/rounded_bottom_flask_boundary_map_46.png b/resources/rounded_bottom_flask_boundary_map_46.png
new file mode 100644
index 0000000..4af5d1b
Binary files /dev/null and b/resources/rounded_bottom_flask_boundary_map_46.png differ