Boundary fix, at small performance cost.

elements/alert.go

@@ -0,0 +1,49 @@
+package elements
+
+import (
+	"fluids/fonts"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/text/v2"
+)
+
+const (
+	AlertWidth  = 50
+	AlertHeight = 150
+)
+
+type Alert struct {
+	Sprite         *ebiten.Image
+	text           string
+	textfacesource *text.GoTextFaceSource
+}
+
+func NewAlert() *Alert {
+	a := &Alert{
+		Sprite:         ebiten.NewImage(AlertWidth, AlertHeight),
+		textfacesource: fonts.PixelFont,
+	}
+	return a
+}
+
+func (a *Alert) Draw() {
+	a.Sprite.Clear()
+
+	fnt := &text.GoTextFace{
+		Source: a.textfacesource,
+		Size:   20,
+	}
+
+	_, h := text.Measure(a.text, fnt, 0)
+	top := &text.DrawOptions{}
+	top.GeoM.Translate(0, h)
+	text.Draw(a.Sprite, a.text, fnt, top)
+}
+
+func (a *Alert) Update() {
+
+}
+
+func (a *Alert) SetText(t string) {
+	a.text = t
+}

fonts/fonts.go

@@ -0,0 +1,25 @@
+package fonts
+
+import (
+	"bytes"
+	_ "embed"
+	"log"
+
+	"github.com/hajimehoshi/ebiten/v2/text/v2"
+)
+
+const ()
+
+var (
+	PixelFont *text.GoTextFaceSource
+	//go:embed Rockboxcond12.ttf
+	pixel_fnt []byte
+)
+
+func init() {
+	s, err := text.NewGoTextFaceSource(bytes.NewReader(pixel_fnt))
+	if err != nil {
+		log.Fatal(err)
+	}
+	PixelFont = s
+}

game/game.go

@@ -15,14 +15,13 @@ import (
 )
 
 const (
-	GameWidth          = 640
-	GameHeight         = 360
-	GameParticleCount  = 2000
-	GameGravity        = 2
-	GameParticleRadius = 5
-	GameDamping        = .7
-	GameDeltaTimeStep  = 0.5
-
+	GameWidth           = 640
+	GameHeight          = 360
+	GameParticleCount   = 2000
+	GameGravity         = 2
+	GameParticleRadius  = 5
+	GameDamping         = .7
+	GameDeltaTimeStep   = 0.5
 	GameInfluenceRadius = 30
 )
 
@@ -38,6 +37,7 @@ type Game struct {
 	resolvecollisions bool
 	resolvers         []func(particle *elements.Particle)
 	resolveridx       int
+	alertbox          *elements.Alert
 }
 
 func NewGame() *Game {
@@ -47,6 +47,7 @@ func NewGame() *Game {
 		renderquads:       false,
 		resolvecollisions: false,
 		resolveridx:       0,
+		alertbox:          elements.NewAlert(),
 	}
 
 	g.particlebox = &gamedata.Vector{
@@ -104,6 +105,12 @@ func (g *Game) Draw(screen *ebiten.Image) {
 	if g.renderquads {
 		g.RenderQuadrants(screen)
 	}
+
+	if g.paused {
+		op := &ebiten.DrawImageOptions{}
+		op.GeoM.Translate(50, 50)
+		screen.DrawImage(g.alertbox.Sprite, op)
+	}
 }
 
 func (g *Game) Layout(x, y int) (int, int) {
@@ -230,8 +237,10 @@ func (g *Game) UpdateParticles() {
 		if g.resolvecollisions {
 			g.resolvers[g.resolveridx](particle)
 		}
+	}
 
-		g.BoundParticle(particle)
+	for _, p := range g.particles {
+		g.BoundParticle(p)
 	}
 
 }
@@ -279,22 +288,30 @@ func (g *Game) RenderQuadrants(img *ebiten.Image) {
 }
 
 func (g *Game) ParseInputs() {
+
+	//refresh particles
 	if inpututil.IsKeyJustPressed(ebiten.KeyR) {
 		g.InitializeParticles()
 	}
 
+	//pause simulation
 	if inpututil.IsKeyJustPressed(ebiten.KeyP) {
 		g.paused = !g.paused
+		g.alertbox.SetText("PAUSED")
+		g.alertbox.Draw()
 	}
 
+	//show quadtree quadrants
 	if inpututil.IsKeyJustPressed(ebiten.KeyQ) {
 		g.renderquads = !g.renderquads
 	}
 
+	//enable collision resolution
 	if inpututil.IsKeyJustPressed(ebiten.KeyC) {
 		g.resolvecollisions = !g.resolvecollisions
 	}
 
+	//switch between collision resolvers
 	if inpututil.IsKeyJustPressed(ebiten.KeyLeft) {
 		g.resolveridx = g.resolveridx - 1
 		if g.resolveridx < 0 {
@@ -305,7 +322,6 @@ func (g *Game) ParseInputs() {
 	if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
 		g.resolveridx = (g.resolveridx + 1) % len(g.resolvers)
 	}
-
 }
 
 func (g *Game) RebuildQuadtree() {

go.mod

@@ -8,7 +8,11 @@ require (
 	github.com/ebitengine/gomobile v0.0.0-20250923094054-ea854a63cce1 // indirect
 	github.com/ebitengine/hideconsole v1.0.0 // indirect
 	github.com/ebitengine/purego v0.9.0 // indirect
+	github.com/go-text/typesetting v0.3.0 // indirect
 	github.com/jezek/xgb v1.1.1 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	golang.org/x/image v0.31.0 // indirect
 	golang.org/x/sync v0.17.0 // indirect
 	golang.org/x/sys v0.36.0 // indirect
+	golang.org/x/text v0.29.0 // indirect
 )