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