updates

util/rng.go

@@ -0,0 +1,94 @@
+package util
+
+import (
+	"math"
+	"math/rand"
+	"time"
+)
+
+type RNG struct {
+	seed int64
+	rand *rand.Rand
+}
+
+func NewRNG() *RNG {
+	rng := RNG{}
+
+	// Set the seed to the current time. This can be updated later by the user.
+	rng.seed = time.Now().UTC().UnixNano()
+	rng.rand = rand.New(rand.NewSource(rng.seed))
+
+	return &rng
+}
+
+func (rng *RNG) GetSeed() int64 {
+	return rng.seed
+}
+
+func (rng *RNG) SetSeed(seed int64) {
+	rng.seed = seed
+}
+
+func (rng *RNG) Uniform() float64 {
+	return rng.rand.Float64()
+}
+
+func (rng *RNG) UniformRange(a, b float64) float64 {
+	return a + rng.Uniform() * (b - a)
+}
+
+func (rng *RNG) Normal(mean, stddev float64) float64 {
+
+	var r, x float64
+
+	for r >= 1 || r == 0 {
+		x = rng.UniformRange(-1.0, 1.0)
+		y := rng.UniformRange(-1.0, 1.0)
+		r = x*x + y*y
+	}
+
+	result := x * math.Sqrt(-2 * math.Log(r) / r)
+
+	return mean + stddev * result
+
+}
+
+func (rng *RNG) Percentage() int {
+	return rng.rand.Intn(100)
+}
+
+func (rng *RNG) Range(min, max int) int {
+	if min == max {
+		return min
+	} else {
+		return rng.rand.Intn(max - min) + min
+	}
+}
+
+func (rng *RNG) RangeNegative(min, max int) int {
+	if min == max {
+		return min
+	} else {
+		return rng.rand.Intn(max - min + 1) + min
+	}
+}
+
+func (rng *RNG) GetWeightedEntity(values map[int]int) int {
+	// First up, get the total weight value from the gamemap
+	totalWeight := 0
+	for weight := range values {
+		totalWeight += weight
+	}
+
+	// Next, get a random integer in the range of the total weight
+	r := rng.Range(0, totalWeight)
+
+	for weight, value := range values {
+		r -= value
+		if r <= 0 {
+			return weight
+		}
+	}
+
+	return -1
+}