mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
136 lines
3.5 KiB
Go
136 lines
3.5 KiB
Go
/*
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Copyright 2014 Hajime Hoshi
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package ebiten
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import (
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"math"
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)
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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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//
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// A ColorMatrix is applied to the source alpha color
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// while an Image's pixels' format is alpha premultiplied.
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// Before applying a matrix, a color is un-multiplied, and after applying the matrix,
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// the color is multiplied again.
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type ColorMatrix struct {
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Elements [ColorMatrixDim - 1][ColorMatrixDim]float64
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}
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// ColorMatrixI returns an identity color matrix.
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func ColorMatrixI() ColorMatrix {
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return ColorMatrix{
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[ColorMatrixDim - 1][ColorMatrixDim]float64{
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{1, 0, 0, 0, 0},
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{0, 1, 0, 0, 0},
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{0, 0, 1, 0, 0},
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{0, 0, 0, 1, 0},
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},
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}
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}
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func (c *ColorMatrix) dim() int {
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return ColorMatrixDim
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}
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// Element returns a value of a matrix at (i, j).
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func (c *ColorMatrix) Element(i, j int) float64 {
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return c.Elements[i][j]
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}
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// Concat multiplies a color matrix with the other color matrix.
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func (c *ColorMatrix) Concat(other ColorMatrix) {
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result := ColorMatrix{}
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mul(&other, c, &result)
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*c = result
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}
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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 {
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return isIdentity(c)
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}
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func (c *ColorMatrix) setElement(i, j int, element float64) {
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c.Elements[i][j] = element
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}
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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
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const g = 23434.0 / 32768.0
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const b = 2366.0 / 32768.0
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return ColorMatrix{
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[ColorMatrixDim - 1][ColorMatrixDim]float64{
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{r, g, b, 0, 0},
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{r, g, b, 0, 0},
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{r, g, b, 0, 0},
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{0, 0, 0, 1, 0},
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},
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}
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}
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// ScaleColor returns a color matrix that scales a color matrix by the given color (r, g, b, a).
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func ScaleColor(r, g, b, a float64) ColorMatrix {
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return ColorMatrix{
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[ColorMatrixDim - 1][ColorMatrixDim]float64{
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{r, 0, 0, 0, 0},
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{0, g, 0, 0, 0},
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{0, 0, b, 0, 0},
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{0, 0, 0, a, 0},
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},
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}
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}
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// TranslateColor returns a color matrix that translates a color matrix by the given color (r, g, b, a).
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func TranslateColor(r, g, b, a float64) ColorMatrix {
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return ColorMatrix{
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[ColorMatrixDim - 1][ColorMatrixDim]float64{
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{1, 0, 0, 0, r},
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{0, 1, 0, 0, g},
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{0, 0, 1, 0, b},
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{0, 0, 0, 1, a},
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},
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}
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}
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// RotateHue returns a color matrix to rotate the hue
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func RotateHue(theta float64) ColorMatrix {
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sin, cos := math.Sincos(theta)
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v1 := cos + (1.0-cos)/3.0
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v2 := (1.0/3.0)*(1.0-cos) - math.Sqrt(1.0/3.0)*sin
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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},
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{v3, v1, v2, 0, 0},
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{v2, v3, v1, 0, 0},
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{0, 0, 0, 1, 0},
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},
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}
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}
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func rgba(r, g, b, a uint8) (float64, float64, float64, float64) {
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const max = math.MaxUint8
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rf := float64(r) / max
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gf := float64(g) / max
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bf := float64(b) / max
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af := float64(a) / max
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return rf, gf, bf, af
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}
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