Added particles on splash.

cmd/krampus19/animations.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"math"
+	"math/rand"
 	"time"
 
 	"opslag.de/schobers/geom"
@@ -50,3 +52,77 @@ func (a *sinkAnimation) Animate(start, now time.Duration) bool {
 	a.e.scr.z = progress * 80
 	return true
 }
+
+type splashAnimation struct {
+	particles []splashParticle
+}
+
+func newSplashAnimation(pos geom.Point) *splashAnimation {
+	pos32 := pos.ToF32()
+	a := &splashAnimation{}
+	n := rand.Intn(20) + 4
+	for i := 0; i < n; i++ {
+		angle := rand.Float32() * math.Pi * 2
+		a.particles = append(a.particles, splashParticle{
+			angle:  angle,
+			origin: pos32.Add2D(.45*geom.Cos32(angle), .45*geom.Sin32(angle)), // [-0.45 .. 0.45]
+			speed:  .5*math.Pi + 2*math.Pi*rand.Float32(),                     // [0.5*Pi .. 2.5*Pi)
+			height: .2 + .8*rand.Float32(),                                    // [0.2 .. 1.0)
+			dist:   .5 + .5*rand.Float32(),                                    // [0.5 .. 1.0)
+		})
+	}
+	return a
+}
+
+func (a *splashAnimation) Animate(start, now time.Duration) bool {
+	const duration = 1670 * time.Millisecond
+
+	progress := float32((now-start)*1000/duration) * .001
+	var opaq float32 = 1
+	if progress > .6 {
+		if progress > 1 {
+			opaq = 0
+		} else {
+			opaq = 2.5 - 2.5*progress
+		}
+	}
+	for i, p := range a.particles {
+		progress := geom.Min32(math.Pi, progress*p.speed) / math.Pi
+		a.particles[i].part = particle{
+			opaq: opaq,
+			pos:  p.origin.Add2D(progress*p.dist*geom.Cos32(p.angle), progress*p.dist*geom.Sin32(p.angle)),
+			z:    20 + p.height*-100*geom.Sin32(progress*math.Pi),
+		}
+	}
+	if progress > 1 {
+		return false
+	}
+	return true
+}
+
+type particle struct {
+	pos  geom.PointF32
+	z    float32
+	opaq float32
+}
+
+func splitParticles(y float32, particles []particle) (behind []particle, front []particle) {
+	for _, p := range particles {
+		if p.pos.Y > y {
+			front = append(front, p)
+		} else {
+			behind = append(behind, p)
+		}
+	}
+	return
+}
+
+type splashParticle struct {
+	origin geom.PointF32
+	angle  float32
+	speed  float32
+	height float32
+	dist   float32
+
+	part particle
+}

cmd/krampus19/game.go

@@ -156,7 +156,8 @@ func (g *game) loadAssets() error {
 		"tile_lava_brick.png": "lava_brick",
 		"tile_magma.png":      "magma",
 
-		"ui.png": "ui",
+		"particles.png": "particles",
+		"ui.png":        "ui",
 	})
 	if err != nil {
 		return err
@@ -178,7 +179,7 @@ func (g *game) loadAssets() error {
 	log.Printf("Loaded %d fonts.\n", g.ui.Fonts().Len())
 
 	log.Println("Loading sprites")
-	err = g.loadSprites("brick", "dragon", "lava_brick", "magma", "ui", "villain")
+	err = g.loadSprites("brick", "dragon", "lava_brick", "magma", "particles", "ui", "villain")
 	if err != nil {
 		return err
 	}

cmd/krampus19/playlevel.go

@@ -178,8 +178,21 @@ func (l *playLevel) drawSprite(name, partName string, pos entityLoc) {
 	l.ctx.SpriteDrawer.Draw(name, partName, l.posToScreenF32(pos.pos, pos.z), DrawSpriteOptions{Scale: l.scale})
 }
 
+func (l *playLevel) drawSpriteAlpha(name, partName string, pos entityLoc, alpha float32) {
+	a := byte(alpha * 255)
+	c := allg5.NewColorAlpha(a, a, a, a)
+	l.ctx.SpriteDrawer.Draw(name, partName, l.posToScreenF32(pos.pos, pos.z), DrawSpriteOptions{Scale: l.scale, Tint: &c})
+}
+
 func (l *playLevel) Render(ctx *alui.Context, bounds geom.RectangleF32) {
 	level := l.state.level
+
+	drawParticles := func(particles []particle) {
+		for _, p := range particles {
+			l.drawSpriteAlpha("particles", "splash", entityLoc{p.pos, p.z}, p.opaq)
+		}
+	}
+
 	for i, t := range level.tiles {
 		pos := geom.Pt(i%level.width, i/level.width)
 		scr := entityLoc{pos.ToF32(), 0}
@@ -194,8 +207,11 @@ func (l *playLevel) Render(ctx *alui.Context, bounds geom.RectangleF32) {
 			l.drawSprite("magma", "magma", scr)
 			brick := l.state.FindSunkenBrick(pos)
 			if brick != nil {
+				behind, front := splitParticles(scr.pos.Y, l.state.Particles(pos))
+				drawParticles(behind)
 				l.drawSprite("brick", "brick", brick.scr)
 				l.drawSprite("magma", "sunken_overlay", scr)
+				drawParticles(front)
 			}
 		}
 	}

cmd/krampus19/playlevelstate.go

@@ -18,6 +18,7 @@ type playLevelState struct {
 	villain *entity
 	bricks  entityList
 	sunken  entityList
+	splash  map[geom.Point]*splashAnimation
 
 	steps      int
 	complete   bool
@@ -33,6 +34,20 @@ func (s *playLevelState) Entities() entityList {
 	return entities.Add(s.player).Add(s.villain).AddList(s.bricks)
 }
 
+func (s *playLevelState) Particles(at geom.Point) []particle {
+	var particles []particle
+	for pos, ani := range s.splash {
+		if pos != at {
+			continue
+		}
+		log.Println("Found particles at", at)
+		for _, p := range ani.particles {
+			particles = append(particles, p.part)
+		}
+	}
+	return particles
+}
+
 func (s *playLevelState) FindSunkenBrick(pos geom.Point) *entity {
 	return s.sunken.FindEntity(pos)
 }
@@ -50,6 +65,7 @@ func (s *playLevelState) Init(ctx *Context, pack, level string, onComplete func(
 	s.level = s.pack.levels[level]
 	s.bricks = nil
 	s.sunken = nil
+	s.splash = map[geom.Point]*splashAnimation{}
 	for i, e := range s.level.entities {
 		switch e {
 		case entityTypeBrick:
@@ -116,6 +132,12 @@ func (s *playLevelState) TryPlayerMove(dir geom.Point, key allg5.Key) {
 				s.bricks = s.bricks.Remove(brickTo)
 				s.sunken = s.sunken.Add(brick)
 				s.ani.Start(s.ctx.Tick, newSinkAnimation(brick))
+
+				splash := newSplashAnimation(brickTo)
+				s.splash[brickTo] = splash
+				s.ani.StartFn(s.ctx.Tick, splash, func() {
+					delete(s.splash, brickTo)
+				})
 			}
 		})
 	}

cmd/krampus19/res/sprites/particles.txt

@@ -0,0 +1,11 @@
+sprite:
+texture: particles
+
+part:
+name: splash
+sub_texture: 0,0,96,96
+anchor: 48,48
+scale: 6
+:part
+
+:sprite