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 }