Guntis Smaukstelis
48 lines
1.7 KiB
TypeScript
48 lines
1.7 KiB
TypeScript
import { ColorEntry } from '../harmonie/draw/constants'
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type RGBu8 = [number, number, number]
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type RGBAu8 = [number, number, number, number]
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export function interpolateColors(value: number, a: RGBu8, b: RGBu8): RGBAu8 {
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const color = a.slice(0).map((from, i) => {
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const to = b[i]
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const delta = (to - from) * (value/255)
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return from + delta
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})
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return [...color, 255] as RGBAu8
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}
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export function valueToColorThreshold(value: number, colorArr: ColorEntry[]): [number, number, number, number] {
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const entries = colorArr.filter(t => t.value <= value)
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return entries.length === 0 ? colorArr[colorArr.length-1].color : entries[0].color
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}
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export function valueToColorInterpolated(value: number, colorArr: ColorEntry[]): [number, number, number, number] {
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const minIdx = colorArr.length-1
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if (value >= colorArr[0].value) return colorArr[0].color
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if (value <= colorArr[minIdx].value) return colorArr[minIdx].color
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let closeMax: ColorEntry = colorArr[0]
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let closeMin: ColorEntry = colorArr[minIdx]
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for (let i=0; i<colorArr.length; i++) {
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const currentDeg = colorArr[i].value
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if (currentDeg >= value && currentDeg < closeMax.value) {
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closeMax = colorArr[i]
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}
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if (currentDeg <= value && currentDeg > closeMin.value) {
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closeMin = colorArr[i]
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}
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}
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const maxDeg = closeMax.color.slice(0, 3) as [number, number, number]
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const minDeg = closeMin.color.slice(0, 3) as [number, number, number]
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const scale = Math.abs(closeMax.value - closeMin.value)
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const delta = 255*(value - closeMin.value)/scale
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const rgba = interpolateColors(delta, minDeg, maxDeg)
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return rgba
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}
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