LEDController/internal/patterns/plasma.go

package patterns

import (
	"math"
)

type RGBcolor = [3]byte

func floatColorToIntColor(val float64) byte {
	return byte(val*256 - 0.5)
}

func plasmaRGBFromVal(val byte) (byte, byte, byte) {
	var r byte
	var g byte
	var b byte
	if val < 85 {
		r = val * 3
		g = 255 - r
		b = 0
	} else if val < 170 {
		b = (val - 85) * 3
		r = 255 - b
		g = 0
	} else {
		g = (val - 170) * 3
		b = 255 - g
		r = 0
	}
	return r, g, b
}

func LinearPlasma(l int) []byte {
	line := make([]byte, l*3)
	for i := 0; i < l*3; i += 3 {
		val := byte(i % 256)
		r, g, b := plasmaRGBFromVal(val)
		line[i] = r
		line[i+1] = g
		line[i+2] = b
	}
	return line
}

func linearFromVal(val byte) (byte, byte, byte) {
	var r byte = val
	var g byte = 0
	var b byte = 0
	return r, g, b
}

func positiveModF(val float64) float64 {
	_, val = math.Modf(val)
	if val < 0 {
		return val + 1.0
	}
	return val
}

func colorPlasmaFromFloatVal(val float64) (byte, byte, byte) {
	var r byte
	var g byte
	var b byte
	val = positiveModF(val) * 3.0
	if val < 1.0 {
		r = floatColorToIntColor(val)
		g = floatColorToIntColor(1.0 - val)
		b = 0
	} else if val < 2.0 {
		b = floatColorToIntColor(val - 1.0)
		r = floatColorToIntColor(1.0 - (val - 1.0))
		g = 0.0
	} else {
		g = floatColorToIntColor(val - 2.0)
		b = floatColorToIntColor(1.0 - (val - 2.0))
		r = 0.0
	}
	return r, g, b
}

var palletteOffset float64 = 0.0

func PlasmaPanel(w int, h int, speed uint16) [][]RGBcolor {
	grid := make([][]RGBcolor, w)
	for i := 0; i < w; i++ {
		grid[i] = make([]RGBcolor, h)
	}

	// pbrook didn't say what DT is for... so it resolves to 0.05
	palletteOffset -= 0.05 / 1.0
	if palletteOffset < 0 {
		palletteOffset += 1.0
	}

	offset := 0.5 // center offset
	scaleW := math.Pi * 2.0 / float64(w)
	scaleH := math.Pi * 2.0 / float64(h)

	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			u := math.Cos((float64(x) + offset) * scaleW)
			v := math.Cos((float64(y) + offset) * scaleH)
			j := math.Cos(offset * scaleW) // 2D - No Z
			e := (u + v + j + 3.0) / 6.0
			r, g, b := colorPlasmaFromFloatVal(palletteOffset + e)
			var rgb [3]byte
			rgb[0] = r
			rgb[1] = g
			rgb[2] = b
			grid[x][y] = rgb
		}
	}
	return grid
}