particles

particle.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"math"
+	"math/rand"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+type particle struct {
+	pos, speed rl.Vector2
+}
+
+type particleSpawner struct {
+	particles []particle
+}
+
+func (p *particle) update(g *game) {
+	p.pos = rl.Vector2Add(p.pos, rl.Vector2Scale(p.speed, rl.GetFrameTime()*g.gameSpeed))
+	p.pos.Y = float32(math.Mod(float64(p.pos.Y), float64(g.arenaHeight)))
+	rl.DrawPixelV(p.pos, rl.White)
+}
+
+func (s *particleSpawner) update(g *game) {
+	for i := range s.particles {
+		(&s.particles[i]).update(g)
+	}
+}
+
+func starsBackground(g *game) *particleSpawner {
+	s := new(particleSpawner)
+	n := 2000
+	s.particles = make([]particle, n)
+	for i := range n {
+		rWidth := float32(rand.Int31n(g.arenaWidth))
+		rHeight := float32(rand.Int31n(g.arenaHeight))
+		s.particles[i] = particle{
+			pos:   rl.Vector2{X: rWidth, Y: rHeight},
+			speed: rl.Vector2{X: 0, Y: rand.Float32()*123 + 87},
+		}
+
+	}
+	return s
+}