58 lines
1.3 KiB
Go
58 lines
1.3 KiB
Go
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package poindexter
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import (
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"math"
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"math/rand"
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)
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// RampUp returns a linear ramp from 0 to 1 over the given duration.
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// The result is clamped to [0, 1].
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func RampUp(elapsed, duration float64) float64 {
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if duration <= 0 {
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return 1
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}
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return Clamp(elapsed/duration, 0, 1)
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}
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// SineWave returns a sine value with the given period and amplitude.
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// Output range is [-amplitude, amplitude].
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func SineWave(t, period, amplitude float64) float64 {
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if period == 0 {
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return 0
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}
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return math.Sin(t/period*2*math.Pi) * amplitude
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}
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// Oscillate modulates a base value with a sine wave.
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// Returns base * (1 + sin(t/period*2π) * amplitude).
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func Oscillate(base, t, period, amplitude float64) float64 {
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if period == 0 {
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return base
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}
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return base * (1 + math.Sin(t/period*2*math.Pi)*amplitude)
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}
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// Noise generates seeded pseudo-random values.
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type Noise struct {
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rng *rand.Rand
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}
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// NewNoise creates a seeded noise generator.
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func NewNoise(seed int64) *Noise {
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return &Noise{rng: rand.New(rand.NewSource(seed))}
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}
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// Float64 returns a random value in [-variance, variance].
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func (n *Noise) Float64(variance float64) float64 {
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return (n.rng.Float64() - 0.5) * 2 * variance
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}
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// Int returns a random integer in [0, max).
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// Returns 0 if max <= 0.
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func (n *Noise) Int(max int) int {
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if max <= 0 {
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return 0
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}
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return n.rng.Intn(max)
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}
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