/
color.go
112 lines (95 loc) · 2.59 KB
/
color.go
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// Copyright 2019 Cogent Core. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package math32
import "image/color"
// official correct ones:
// SRGBFromLinear converts a color with linear gamma correction to SRGB standard 2.4 gamma
// with offsets.
func SRGBFromLinear(lin float32) float32 {
if lin <= 0.0031308 {
return lin * 12.92
}
return Pow(lin, 1.0/2.4)*1.055 - 0.055
}
// SRGBToLinear converts a color with SRGB gamma correction to SRGB standard 2.4 gamma
// with offsets
func SRGBToLinear(sr float32) float32 {
if sr <= 0.04045 {
return sr / 12.92
}
return Pow((sr+0.055)/1.055, 2.4)
}
/*
// rough-and-ready approx used in many cases:
func SRGBFromLinear(lin float32) float32 {
return Pow(lin, 1.0/2.2)
}
func SRGBToLinear(sr float32) float32 {
return Pow(sr, 2.2)
}
*/
// NewVector3Color returns a Vector3 from Go standard color.Color
// (R,G,B components only)
func NewVector3Color(clr color.Color) Vector3 {
v3 := Vector3{}
v3.SetColor(clr)
return v3
}
// SetColor sets from Go standard color.Color
// (R,G,B components only)
func (v *Vector3) SetColor(clr color.Color) {
r, g, b, _ := clr.RGBA()
v.X = float32(r) / 0xffff
v.Y = float32(g) / 0xffff
v.Z = float32(b) / 0xffff
}
// NewVector4Color returns a Vector4 from Go standard color.Color
// (full R,G,B,A components)
func NewVector4Color(clr color.Color) Vector4 {
v4 := Vector4{}
v4.SetColor(clr)
return v4
}
// SetColor sets a Vector4 from Go standard color.Color
func (v *Vector4) SetColor(clr color.Color) {
r, g, b, a := clr.RGBA()
v.X = float32(r) / 0xffff
v.Y = float32(g) / 0xffff
v.Z = float32(b) / 0xffff
v.W = float32(a) / 0xffff
}
// SRGBFromLinear returns an SRGB color space value from a linear source
func (v Vector3) SRGBFromLinear() Vector3 {
nv := Vector3{}
nv.X = SRGBFromLinear(v.X)
nv.Y = SRGBFromLinear(v.Y)
nv.Z = SRGBFromLinear(v.Z)
return nv
}
// SRGBToLinear returns a linear color space value from a SRGB source
func (v Vector3) SRGBToLinear() Vector3 {
nv := Vector3{}
nv.X = SRGBToLinear(v.X)
nv.Y = SRGBToLinear(v.Y)
nv.Z = SRGBToLinear(v.Z)
return nv
}
// SRGBFromLinear returns an SRGB color space value from a linear source
func (v Vector4) SRGBFromLinear() Vector4 {
nv := Vector4{}
nv.X = SRGBFromLinear(v.X)
nv.Y = SRGBFromLinear(v.Y)
nv.Z = SRGBFromLinear(v.Z)
nv.W = v.W
return nv
}
// SRGBToLinear returns a linear color space value from a SRGB source
func (v Vector4) SRGBToLinear() Vector4 {
nv := Vector4{}
nv.X = SRGBToLinear(v.X)
nv.Y = SRGBToLinear(v.Y)
nv.Z = SRGBToLinear(v.Z)
nv.W = v.W
return nv
}