tins2020/noisemap.go

package tins2020

import "opslag.de/schobers/geom/noise"

func clipNormalized(x float64) float64 {
	if x < 0 {
		return 0
	}
	if x > 1 {
		return 1
	}
	return x
}

type NoiseMap interface {
	Seed() int64
	Value(x, y int) float64
}

func NewNoiseMap(seed int64) NoiseMap {
	return &noiseMap{
		noise:     noise.NewPerlin(seed),
		alpha:     2,
		beta:      4,
		harmonics: 2,
	}
}

type noiseMap struct {
	noise       *noise.Perlin
	alpha, beta float64
	harmonics   int
}

// Value generates the noise value for an x/y pair.
func (m noiseMap) Value(x, y int) float64 {
	value := m.noise.Noise2D(float64(x)*.01, float64(y)*.01, m.alpha, m.beta, m.harmonics)*.565 + .5
	return clipNormalized(value)
}

func (m noiseMap) Seed() int64 { return m.noise.Seed }

func NewRandomNoiseMap(seed int64) NoiseMap {
	return &randomNoiseMap{noise.NewPerlin(seed)}
}

type randomNoiseMap struct {
	*noise.Perlin
}

// Value generates the noise value for an x/y pair.
func (m randomNoiseMap) Value(x, y int) float64 {
	value := m.Noise2D(float64(x)*.53, float64(y)*.53, 1.01, 2, 2)*.5 + .5
	return clipNormalized(value)
}

func (m randomNoiseMap) Seed() int64 { return m.Perlin.Seed }