ebiten/colormatrix.go

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/*
Copyright 2014 Hajime Hoshi
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
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package ebiten
import (
"math"
)
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// ColorMatrixDim is a dimension of a ColorMatrix.
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const ColorMatrixDim = 5
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// A ColorMatrix represents a matrix to transform coloring when rendering an image.
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type ColorMatrix struct {
Elements [ColorMatrixDim - 1][ColorMatrixDim]float64
}
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// ColorMatrixI returns an identity color matrix.
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func ColorMatrixI() ColorMatrix {
return ColorMatrix{
[ColorMatrixDim - 1][ColorMatrixDim]float64{
{1, 0, 0, 0, 0},
{0, 1, 0, 0, 0},
{0, 0, 1, 0, 0},
{0, 0, 0, 1, 0},
},
}
}
func (c *ColorMatrix) dim() int {
return ColorMatrixDim
}
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// Element returns a value of a matrix at (i, j).
func (c *ColorMatrix) Element(i, j int) float64 {
return c.Elements[i][j]
}
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// Concat multiplies a color matrix with the other color matrix.
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func (c *ColorMatrix) Concat(other ColorMatrix) {
result := ColorMatrix{}
mul(&other, c, &result)
*c = result
}
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// IsIdentity returns a boolean indicating whether the color matrix is an identity.
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func (c *ColorMatrix) IsIdentity() bool {
return isIdentity(c)
}
func (c *ColorMatrix) setElement(i, j int, element float64) {
c.Elements[i][j] = element
}
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// Monochrome returns a color matrix to make an image monochrome.
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func Monochrome() ColorMatrix {
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const r = 6968.0 / 32768.0
const g = 23434.0 / 32768.0
const b = 2366.0 / 32768.0
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return ColorMatrix{
[ColorMatrixDim - 1][ColorMatrixDim]float64{
{r, g, b, 0, 0},
{r, g, b, 0, 0},
{r, g, b, 0, 0},
{0, 0, 0, 1, 0},
},
}
}
// ScaleColor returns a color matrix that scales a color matrix by the given color (r, g, b, a).
func ScaleColor(r, g, b, a float64) ColorMatrix {
return ColorMatrix{
[ColorMatrixDim - 1][ColorMatrixDim]float64{
{r, 0, 0, 0, 0},
{0, g, 0, 0, 0},
{0, 0, b, 0, 0},
{0, 0, 0, a, 0},
},
}
}
// TranslateColor returns a color matrix that translates a color matrix by the given color (r, g, b, a).
func TranslateColor(r, g, b, a float64) ColorMatrix {
return ColorMatrix{
[ColorMatrixDim - 1][ColorMatrixDim]float64{
{1, 0, 0, 0, r},
{0, 1, 0, 0, g},
{0, 0, 1, 0, b},
{0, 0, 0, 1, a},
},
}
}
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// RotateHue returns a color matrix to rotate the hue
func RotateHue(theta float64) ColorMatrix {
sin, cos := math.Sincos(theta)
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v1 := cos + (1.0-cos)/3.0
v2 := (1.0/3.0)*(1.0-cos) - math.Sqrt(1.0/3.0)*sin
v3 := (1.0/3.0)*(1.0-cos) + math.Sqrt(1.0/3.0)*sin
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return ColorMatrix{
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[ColorMatrixDim - 1][ColorMatrixDim]float64{
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{v1, v2, v3, 0, 0},
{v3, v1, v2, 0, 0},
{v2, v3, v1, 0, 0},
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{0, 0, 0, 1, 0},
},
}
}
func rgba(r, g, b, a uint8) (float64, float64, float64, float64) {
const max = math.MaxUint8
rf := float64(r) / max
gf := float64(g) / max
bf := float64(b) / max
af := float64(a) / max
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return rf, gf, bf, af
}