From 311e9d56d32cf631946406d50fbb3029198d1ed7 Mon Sep 17 00:00:00 2001
From: Louis Dalibard <ontake@ontake.dev>
Date: Tue, 19 Nov 2024 22:41:47 +0100
Subject: [PATCH] feat: particle tweaks

---
 config/config.go | 8 +++++---
 main.go          | 7 ++++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/config/config.go b/config/config.go
index e181509..f19f73f 100644
--- a/config/config.go
+++ b/config/config.go
@@ -35,6 +35,7 @@ type ConfigS struct {
 	ParticleMinSize                  float32
 	ParticleMaxSize                  float32
 	ParticleAcceleration             float32
+	ParticleDrag                     float32
 }
 
 var DefaultConfig = ConfigS{
@@ -54,11 +55,12 @@ var DefaultConfig = ConfigS{
 	LineThickness:                    3,
 	LineInvSqrtOpacityControl:        false,
 	Particles:                        true,
-	ParticleGenPerFrameEveryXSamples: 9600,
-	ParticleMaxCount:                 3000,
+	ParticleGenPerFrameEveryXSamples: 2000,
+	ParticleMaxCount:                 600,
 	ParticleMinSize:                  0.2,
 	ParticleMaxSize:                  2.0,
-	ParticleAcceleration:             0.01,
+	ParticleAcceleration:             0.015,
+	ParticleDrag:                     5.0,
 }
 
 var Config ConfigS
diff --git a/main.go b/main.go
index a78f8f9..7cf720e 100644
--- a/main.go
+++ b/main.go
@@ -61,7 +61,7 @@ func (g *Game) Draw(screen *ebiten.Image) {
 				}
 				particles.Particles = append(particles.Particles, particles.Particle{
 					X:    float32(AX) * config.Config.Gain,
-					Y:    float32(AY) * config.Config.Gain,
+					Y:    -float32(AY) * config.Config.Gain,
 					VX:   0,
 					VY:   0,
 					Size: rand.Float32()*(config.Config.ParticleMaxSize-config.Config.ParticleMinSize) + config.Config.ParticleMinSize,
@@ -78,8 +78,9 @@ func (g *Game) Draw(screen *ebiten.Image) {
 		norm := math32.Sqrt(particles.Particles[i].X*particles.Particles[i].X + particles.Particles[i].Y*particles.Particles[i].Y)
 		particles.Particles[i].X += particle.VX / float32(ebiten.ActualTPS())
 		particles.Particles[i].Y += particle.VY / float32(ebiten.ActualTPS())
-		particles.Particles[i].VX += config.Config.ParticleAcceleration * particle.X / norm * S / float32(ebiten.ActualTPS())
-		particles.Particles[i].VY += config.Config.ParticleAcceleration * particle.Y / norm * S / float32(ebiten.ActualTPS())
+		speed := math32.Sqrt(particle.VX*particle.VX + particle.VY*particle.VY)
+		particles.Particles[i].VX += (config.Config.ParticleAcceleration*S - speed*config.Config.ParticleDrag) * particle.X / norm / float32(ebiten.ActualTPS())
+		particles.Particles[i].VY += (config.Config.ParticleAcceleration*S - speed*config.Config.ParticleDrag) * particle.Y / norm / float32(ebiten.ActualTPS())
 	}
 
 	//audio.SampleRingBuffer.Reset()