126 lines
3.1 KiB
Go
126 lines
3.1 KiB
Go
package screen
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import (
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"fmt"
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"image"
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"image/color"
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)
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/*
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See:
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https://mrob.com/pub/xapple2/colors.html
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https://archive.org/details/IIgs_2523063_Master_Color_Values
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*/
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var ntscColorMap = [16]color.Color{
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color.RGBA{0, 0, 0, 255}, // Black
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color.RGBA{227, 30, 96, 255}, // Magenta
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color.RGBA{96, 78, 189, 255}, // Dark Blue
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color.RGBA{255, 68, 253, 255}, // Purple
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color.RGBA{0, 163, 96, 255}, // Dark Green
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color.RGBA{156, 156, 156, 255}, // Grey 1
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color.RGBA{20, 207, 253, 255}, // Medium Blue
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color.RGBA{208, 195, 255, 255}, // Light Blue
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color.RGBA{96, 114, 3, 255}, // Brown
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color.RGBA{255, 106, 60, 255}, // Orange
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color.RGBA{156, 156, 156, 255}, // Grey 2
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color.RGBA{255, 160, 208, 255}, // Pink
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color.RGBA{20, 245, 60, 255}, // Green
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color.RGBA{208, 221, 141, 255}, // Yellow
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color.RGBA{114, 255, 208, 255}, // Aquamarine
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color.RGBA{255, 255, 255, 255}, // White
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}
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var attenuatedColorMap = buildAttenuatedColorMap(ntscColorMap)
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func buildAttenuatedColorMap(colorMap [16]color.Color) [16]color.Color {
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colors := [16]color.Color{}
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for i := 0; i < len(colorMap); i++ {
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r, g, b, _ := colorMap[i].RGBA()
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colors[i] = color.RGBA64{
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uint16(r / 2), uint16(g / 2), uint16(b / 2),
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65535,
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}
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}
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return colors
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}
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/*
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var rgbColorMap = [16]color.Color{
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color.RGBA{0, 0, 0, 255}, // Black
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color.RGBA{221, 0, 51, 255}, // Magenta
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color.RGBA{0, 0, 153, 255}, // Dark Blue
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color.RGBA{221, 34, 221, 255}, // Purple
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color.RGBA{0, 119, 34, 255}, // Dark Green
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color.RGBA{85, 85, 85, 255}, // Grey 1
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color.RGBA{34, 34, 255, 255}, // Medium Blue
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color.RGBA{102, 170, 255, 255}, // Light Blue
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color.RGBA{136, 85, 0, 255}, // Brown
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color.RGBA{255, 102, 0, 255}, // Orange
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color.RGBA{170, 170, 170, 255}, // Grey 2
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color.RGBA{255, 153, 136, 255}, // Pink
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color.RGBA{17, 221, 0, 255}, // Green
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color.RGBA{255, 255, 0, 255}, // Yellow
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color.RGBA{68, 255, 153, 255}, // Aquamarine
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color.RGBA{255, 255, 255, 255}, // White
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}
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*/
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func filterNTSCColor(in *image.RGBA, mask *image.Alpha, screenMode int) *image.RGBA {
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colorMap := ntscColorMap // or rgbColorMap
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colorMapLow := ntscColorMap
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if screenMode == ScreenModeNTSC {
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colorMapLow = attenuatedColorMap
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}
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b := in.Bounds()
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width := b.Dx()
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height := b.Dy()
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size := image.Rect(0, 0, width+4, height)
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out := image.NewRGBA(size)
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if width < 2*hiResWidth {
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panic(fmt.Sprintf("The image has width %v. We can't apply the NTSC filter.", width))
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}
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for y := 0; y < height; y++ {
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// We store the last four bits. We start with 0000
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v := 0
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for x := 0; x < width; x++ {
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cIn := in.At(x, y)
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r, _, _, _ := cIn.RGBA()
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pos := 1 << uint(x%4)
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if r != 0 {
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v |= pos
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} else {
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v &^= pos
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}
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var cOut color.Color
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if r != 0 {
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cOut = colorMap[v]
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} else {
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cOut = colorMapLow[v]
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}
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if mask != nil {
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// RGB mode7
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_, _, _, a := mask.At(x, y).RGBA()
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if a > 0 {
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cOut = cIn
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}
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}
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out.Set(x, y, cOut)
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}
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// We fade for the last three positions
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for x := width; x < width+4; x++ {
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v >>= 1
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cOut := colorMap[v]
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out.Set(x, y, cOut)
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}
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}
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return out
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}
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