init

world/world.go

@@ -0,0 +1,91 @@
+package world
+
+import (
+	"wh/config"
+	"wh/fixed"
+	"wh/rng"
+)
+
+// Ore identifies a raw material.
+type Ore int
+
+const (
+	Iron Ore = iota
+	Nickel
+	Ice
+	Platinum
+	NumOre
+)
+
+func (o Ore) String() string {
+	return [...]string{"iron", "nickel", "ice", "platinum"}[o]
+}
+
+type Asteroid struct {
+	ID    int64
+	Orbit Orbit
+	Ore   [NumOre]int64 // remaining kilograms of each ore
+}
+
+func (a *Asteroid) TotalOre() int64 {
+	var t int64
+	for _, v := range a.Ore {
+		t += v
+	}
+	return t
+}
+
+// Station is the dropoff point, on a circular orbit in the ecliptic plane.
+type Station struct {
+	Orbit Orbit
+}
+
+// Stream labels keep independent generation phases from sharing randomness.
+const (
+	labelBelt = iota + 1
+	labelStation
+)
+
+// Generate builds the asteroid field and station from the config seed.
+func Generate(cfg config.Config) ([]Asteroid, Station) {
+	r := rng.Derive(cfg.Seed, labelBelt)
+	asts := make([]Asteroid, cfg.AsteroidCount)
+	for i := range asts {
+		a := r.FixedRange(cfg.BeltInner, cfg.BeltOuter)
+		asts[i] = Asteroid{
+			ID: int64(i + 1),
+			Orbit: Orbit{
+				A:      a,
+				Period: PeriodFor(a, cfg.OrbitSpeed),
+				M0:     r.FixedRange(0, fixed.TwoPi),
+				Node:   r.FixedRange(0, fixed.TwoPi),
+				// Bias inclination low (squared uniform).
+				Inc: r.Fixed().Mul(r.Fixed()).Mul(cfg.MaxInclination),
+			},
+		}
+		// Each asteroid has a total mass and a random mix of ores.
+		total := int64(50_000) + int64(r.Intn(950_000))
+		var weights [NumOre]uint64
+		var wsum uint64
+		for o := range weights {
+			weights[o] = r.Intn(100) + 1
+			wsum += weights[o]
+		}
+		// Platinum is rare: only a fifth of asteroids carry much of it.
+		if r.Intn(5) != 0 {
+			wsum -= weights[Platinum]
+			weights[Platinum] = 0
+		}
+		for o := range weights {
+			asts[i].Ore[o] = total * int64(weights[o]) / int64(wsum)
+		}
+	}
+	sr := rng.Derive(cfg.Seed, labelStation)
+	a := (cfg.BeltInner + cfg.BeltOuter).DivInt(2)
+	st := Station{Orbit: Orbit{
+		A:      a,
+		Period: PeriodFor(a, cfg.OrbitSpeed),
+		M0:     sr.FixedRange(0, fixed.TwoPi),
+	}}
+	return asts, st
+}