34 lines
755 B
Go
34 lines
755 B
Go
package chart
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import "git.fireandbrimst.one/aw/go-chart/drawing"
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// Jet is a color map provider based on matlab's jet color map.
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func Jet(v, vmin, vmax float64) drawing.Color {
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c := drawing.Color{R: 0xff, G: 0xff, B: 0xff, A: 0xff} // white
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var dv float64
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if v < vmin {
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v = vmin
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}
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if v > vmax {
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v = vmax
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}
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dv = vmax - vmin
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if v < (vmin + 0.25*dv) {
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c.R = 0
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c.G = drawing.ColorChannelFromFloat(4 * (v - vmin) / dv)
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} else if v < (vmin + 0.5*dv) {
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c.R = 0
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c.B = drawing.ColorChannelFromFloat(1 + 4*(vmin+0.25*dv-v)/dv)
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} else if v < (vmin + 0.75*dv) {
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c.R = drawing.ColorChannelFromFloat(4 * (v - vmin - 0.5*dv) / dv)
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c.B = 0
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} else {
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c.G = drawing.ColorChannelFromFloat(1 + 4*(vmin+0.75*dv-v)/dv)
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c.B = 0
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}
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return c
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}
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