big refactor

rng.go

@@ -0,0 +1,27 @@
+package main
+
+type PseudoRNG struct {
+	State uint32
+}
+
+func NewRNG(seed int64) *PseudoRNG {
+	return &PseudoRNG{State: uint32(seed)}
+}
+
+func (r *PseudoRNG) NextFloat() float64 {
+	calc := (uint64(r.State)*1664525 + 1013904223) % 4294967296
+	r.State = uint32(calc)
+	return float64(r.State) / 4294967296.0
+}
+
+func (r *PseudoRNG) NextRange(min, max float64) float64 {
+	return min + (r.NextFloat() * (max - min))
+}
+
+func (r *PseudoRNG) PickDef(defs []ObstacleDef) *ObstacleDef {
+	if len(defs) == 0 {
+		return nil
+	}
+	idx := int(r.NextRange(0, float64(len(defs))))
+	return &defs[idx]
+}