mirror of
https://github.com/hajimehoshi/ebiten.git
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274 lines
6.3 KiB
Go
274 lines
6.3 KiB
Go
// Copyright 2014 Hajime Hoshi
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package affine
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import (
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"image/color"
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"math"
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)
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// ColorMDim is a dimension of a ColorM.
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const ColorMDim = 5
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var (
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colorMIdentityBody = []float64{
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1, 0, 0, 0,
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0, 1, 0, 0,
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0, 0, 1, 0,
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0, 0, 0, 1,
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}
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colorMIdentityTranslate = []float64{
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0, 0, 0, 0,
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}
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)
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// A ColorM represents a matrix to transform coloring when rendering an image.
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//
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// A ColorM 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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//
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// The initial value is identity.
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type ColorM struct {
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// When elements is nil, this matrix is identity.
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// elements is immutable and a new array must be created when updating.
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body []float64 // TODO: Transpose this to pass this OpenGL easily
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translate []float64
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}
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func (c *ColorM) Reset() {
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c.body = nil
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c.translate = nil
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}
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func clamp(x float64) float64 {
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if x > 1 {
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return 1
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}
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if x < 0 {
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return 0
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}
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return x
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}
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func (c *ColorM) Apply(clr color.Color) color.Color {
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if c.body == nil {
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return clr
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}
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r, g, b, a := clr.RGBA()
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if a == 0 {
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return color.Transparent
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}
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// Unmultiply alpha
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rf := float64(r) / float64(a)
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gf := float64(g) / float64(a)
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bf := float64(b) / float64(a)
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af := float64(a) / 0xffff
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eb := c.body
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et := c.translate
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rf2 := eb[0]*rf + eb[1]*gf + eb[2]*bf + eb[3]*af + et[0]
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gf2 := eb[4]*rf + eb[5]*gf + eb[6]*bf + eb[7]*af + et[1]
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bf2 := eb[8]*rf + eb[9]*gf + eb[10]*bf + eb[11]*af + et[2]
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af2 := eb[12]*rf + eb[13]*gf + eb[14]*bf + eb[15]*af + et[3]
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rf2 = clamp(rf2)
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gf2 = clamp(gf2)
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bf2 = clamp(bf2)
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af2 = clamp(af2)
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return color.NRGBA64{
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R: uint16(rf2 * 0xffff),
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G: uint16(gf2 * 0xffff),
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B: uint16(bf2 * 0xffff),
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A: uint16(af2 * 0xffff),
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}
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}
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func (c *ColorM) UnsafeElements() ([]float64, []float64) {
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if c.body == nil {
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c.body = colorMIdentityBody
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c.translate = colorMIdentityTranslate
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}
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return c.body, c.translate
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}
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// SetElement sets an element at (i, j).
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func (c *ColorM) SetElement(i, j int, element float64) {
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if c.body == nil {
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c.body = colorMIdentityBody
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c.translate = colorMIdentityTranslate
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}
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if j < (ColorMDim - 1) {
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es := make([]float64, len(c.body))
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copy(es, c.body)
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es[i*(ColorMDim-1)+j] = element
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c.body = es
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} else {
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es := make([]float64, len(c.translate))
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copy(es, c.translate)
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es[i] = element
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c.translate = es
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}
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}
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func (c *ColorM) Equals(other *ColorM) bool {
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if c.body == nil {
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if other.body == nil {
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return true
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}
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c.body = colorMIdentityBody
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c.translate = colorMIdentityTranslate
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}
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if other.body == nil {
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other.body = colorMIdentityBody
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other.translate = colorMIdentityTranslate
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}
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for i := range c.body {
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if c.body[i] != other.body[i] {
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return false
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}
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}
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for i := range c.translate {
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if c.translate[i] != other.translate[i] {
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return false
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}
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}
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return true
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}
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// Concat multiplies a color matrix with the other color matrix.
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// This is same as muptiplying the matrix other and the matrix c in this order.
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func (c *ColorM) Concat(other *ColorM) {
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if c.body == nil {
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c.body = colorMIdentityBody
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c.translate = colorMIdentityTranslate
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}
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if other.body == nil {
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other.body = colorMIdentityBody
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other.translate = colorMIdentityTranslate
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}
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c.body = mulSquare(other.body, c.body, ColorMDim-1)
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lhsb := other.body
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lhst := other.translate
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rhst := c.translate
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c.translate = []float64{
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lhsb[0]*rhst[0] + lhsb[1]*rhst[1] + lhsb[2]*rhst[2] + lhsb[3]*rhst[3] + lhst[0],
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lhsb[4]*rhst[0] + lhsb[5]*rhst[1] + lhsb[6]*rhst[2] + lhsb[7]*rhst[3] + lhst[1],
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lhsb[8]*rhst[0] + lhsb[9]*rhst[1] + lhsb[10]*rhst[2] + lhsb[11]*rhst[3] + lhst[2],
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lhsb[12]*rhst[0] + lhsb[13]*rhst[1] + lhsb[14]*rhst[2] + lhsb[15]*rhst[3] + lhst[3],
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}
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}
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// Add is deprecated.
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func (c *ColorM) Add(other ColorM) {
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// Do nothing.
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}
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// Scale scales the matrix by (r, g, b, a).
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func (c *ColorM) Scale(r, g, b, a float64) {
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if c.body == nil {
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c.body = []float64{
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r, 0, 0, 0,
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0, g, 0, 0,
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0, 0, b, 0,
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0, 0, 0, a,
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}
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c.translate = colorMIdentityTranslate
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return
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}
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es := make([]float64, len(c.body))
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copy(es, c.body)
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for i := 0; i < ColorMDim-1; i++ {
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es[i] *= r
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es[i+(ColorMDim-1)] *= g
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es[i+(ColorMDim-1)*2] *= b
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es[i+(ColorMDim-1)*3] *= a
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}
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c.body = es
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c.translate = []float64{
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c.translate[0] * r,
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c.translate[1] * g,
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c.translate[2] * b,
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c.translate[3] * a,
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}
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}
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// Translate translates the matrix by (r, g, b, a).
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func (c *ColorM) Translate(r, g, b, a float64) {
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if c.body == nil {
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c.body = colorMIdentityBody
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c.translate = []float64{r, g, b, a}
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return
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}
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es := make([]float64, len(c.translate))
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copy(es, c.translate)
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es[0] += r
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es[1] += g
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es[2] += b
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es[3] += a
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c.translate = es
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}
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var (
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// The YCbCr value ranges are:
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// Y: [ 0 - 1 ]
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// Cb: [-0.5 - 0.5]
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// Cr: [-0.5 - 0.5]
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rgbToYCbCr = ColorM{
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body: []float64{
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0.2990, 0.5870, 0.1140, 0,
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-0.1687, -0.3313, 0.5000, 0,
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0.5000, -0.4187, -0.0813, 0,
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0, 0, 0, 1,
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},
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translate: []float64{0, 0, 0, 0},
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}
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yCbCrToRgb = ColorM{
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body: []float64{
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1, 0, 1.40200, 0,
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1, -0.34414, -0.71414, 0,
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1, 1.77200, 0, 0,
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0, 0, 0, 1,
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},
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translate: []float64{0, 0, 0, 0},
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}
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)
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// ChangeHSV changes HSV (Hue-Saturation-Value) elements.
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// hueTheta is a radian value to ratate hue.
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// saturationScale is a value to scale saturation.
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// valueScale is a value to scale value (a.k.a. brightness).
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//
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// This conversion uses RGB to/from YCrCb conversion.
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func (c *ColorM) ChangeHSV(hueTheta float64, saturationScale float64, valueScale float64) {
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sin, cos := math.Sincos(hueTheta)
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c.Concat(&rgbToYCbCr)
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c.Concat(&ColorM{
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body: []float64{
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1, 0, 0, 0,
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0, cos, -sin, 0,
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0, sin, cos, 0,
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0, 0, 0, 1,
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},
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translate: []float64{0, 0, 0, 0},
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})
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s := saturationScale
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v := valueScale
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c.Scale(v, s*v, s*v, 1)
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c.Concat(&yCbCrToRgb)
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}
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