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pixel.go
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pixel.go
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package multirender
import (
"encoding/binary"
"image/color"
"github.com/xyproto/pf"
)
// Pixel draws a pixel to the pixel buffer
func Pixel(pixels []uint32, x, y int32, c color.RGBA, pitch int32) {
pixels[y*pitch+x] = binary.BigEndian.Uint32([]uint8{c.A, c.R, c.G, c.B})
}
// PixelRGB draws an opaque pixel to the pixel buffer, given red, green and blue
func PixelRGB(pixels []uint32, x, y int32, r, g, b uint8, pitch int32) {
pixels[y*pitch+x] = binary.BigEndian.Uint32([]uint8{0xff, r, g, b})
}
// FastPixel draws a pixel to the pixel buffer, given a uint32 ARGB value
func FastPixel(pixels []uint32, x, y int32, colorValue uint32, pitch int32) {
pixels[y*pitch+x] = colorValue
}
// RGBAToColorValue converts from four bytes to an ARGB uint32 color value
func RGBAToColorValue(r, g, b, a uint8) uint32 {
return binary.BigEndian.Uint32([]uint8{a, r, g, b})
}
// ColorValueToRGBA converts from an ARGB uint32 color value to four bytes
func ColorValueToRGBA(cv uint32) (uint8, uint8, uint8, uint8) {
bs := make([]uint8, 4)
binary.LittleEndian.PutUint32(bs, cv)
// r, g, b, a
return bs[2], bs[1], bs[0], bs[3]
}
// ColorToColorValue converts from color.RGBA to an ARGB uint32 color value
func ColorToColorValue(c color.RGBA) uint32 {
return binary.BigEndian.Uint32([]uint8{c.A, c.R, c.G, c.B})
}
// Extract the alpha component from a ARGB uint32 color value
func Alpha(cv uint32) uint8 {
return uint8((cv & 0xff000000) >> 24)
}
// Extract the red component from a ARGB uint32 color value
func Red(cv uint32) uint8 {
return uint8((cv & 0xff0000) >> 16)
}
// Extract the green component from a ARGB uint32 color value
func Green(cv uint32) uint8 {
return uint8((cv & 0xff00) >> 8)
}
// Extract the blue component from a ARGB uint32 color value
func Blue(cv uint32) uint8 {
return uint8(cv & 0xff)
}
// Extract the color value / intensity from a ARGB uint32 color value
func ValueWithAlpha(cv uint32) uint8 {
// TODO: This can be optimized
bs := make([]uint8, 4)
binary.LittleEndian.PutUint32(bs, cv)
grayscaleColor := float32(bs[2]+bs[1]+bs[0]) / float32(3)
alpha := float32(bs[3]) / float32(255)
return uint8(grayscaleColor * alpha)
}
// Extract the color value / intensity from a ARGB uint32 color value.
// Ignores alpha.
func Value(cv uint32) uint8 {
// TODO: This can be optimized
bs := make([]uint8, 4)
binary.LittleEndian.PutUint32(bs, cv)
grayscaleColor := float32(bs[2]+bs[1]+bs[0]) / float32(3)
return uint8(grayscaleColor)
}
// RemoveRed removes all red color.
func RemoveRed(cores int, pixels []uint32) {
pf.Map(cores, pf.RemoveRed, pixels)
}
// RemoveGreen removes all green color.
func RemoveGreen(cores int, pixels []uint32) {
pf.Map(cores, pf.RemoveGreen, pixels)
}
// RemoveBlue removes all blue color.
func RemoveBlue(cores int, pixels []uint32) {
pf.Map(cores, pf.RemoveBlue, pixels)
}
// Turn on all the red bits
func SetRedBits(cores int, pixels []uint32) {
pf.Map(cores, pf.SetRedBits, pixels)
}
// Turn on all the green bits
func SetGreenBits(cores int, pixels []uint32) {
pf.Map(cores, pf.SetGreenBits, pixels)
}
// Turn on all the blue bits
func SetBlueBits(cores int, pixels []uint32) {
pf.Map(cores, pf.SetBlueBits, pixels)
}
// Turn on all the alpha bits
func OrAlpha(cores int, pixels []uint32) {
pf.Map(cores, pf.OrAlpha, pixels)
}
// Return a pixel, with position wraparound instead of overflow
func GetXYWrap(pixels []uint32, x, y, w, h, pitch int32) uint32 {
if x >= w {
x -= w
} else if x < 0 {
x += w
}
if y >= h {
y -= h
} else if y < 0 {
y += h
}
return pixels[y*pitch+x]
}
// Set a pixel, with position wraparound instead of overflow
func SetXYWrap(pixels []uint32, x, y, w, h int32, colorValue uint32, pitch int32) {
if x >= w {
x -= w
} else if x < 0 {
x += w
}
if y >= h {
y -= h
} else if y < 0 {
y += h
}
pixels[y*pitch+x] = colorValue
}
// Return a pixel, with position wraparound instead of overflow
func GetWrap(pixels []uint32, pos, size int32) uint32 {
i := pos
if i >= size {
i -= size
}
if i < 0 {
i += size
}
return pixels[i]
}
// Set a pixel, with position wraparound instead of overflow
func SetWrap(pixels []uint32, pos, size int32, colorValue uint32) {
i := pos
if i >= size {
i -= size
}
if i < 0 {
i += size
}
pixels[i] = colorValue
}
// Blend blends two color values, based on the alpha value
func Blend(c1, c2 uint32) uint32 {
mf := float32(255.0)
a1 := float32(Alpha(c1)) / mf
a2 := float32(Alpha(c2)) / mf
// Weight the color values by alpha, then take the average
r := uint8((float32(Red(c1))*a1 + float32(Red(c2))*a2) / 2.0)
g := uint8((float32(Green(c1))*a1 + float32(Green(c2))*a2) / 2.0)
b := uint8((float32(Blue(c1))*a1 + float32(Blue(c2))*a2) / 2.0)
// Let the new alpha value be the product of the two given alpha values
//a := uint8(a1 * a2 * mf)
// Let the new alpha value be the average of the two given alpha values
a := uint8(((a1 + a2) / 2) * mf)
// Combine the new values to an uint32 (ARGB), and return that
return RGBAToColorValue(r, g, b, a)
}
// Add adds one color value on top of another.
// Only considers the alpha value of the second color value.
// Returns an opaque color.
func Add(c1, c2 uint32) uint32 {
mf := float32(255.0)
a2 := float32(Alpha(c2)) / mf
// Let the second color be affected by the alpha value, but not the first one
r := uint8((float32(Red(c1)) + float32(Red(c2))*a2) / 2.0)
g := uint8((float32(Green(c1)) + float32(Green(c2))*a2) / 2.0)
b := uint8((float32(Blue(c1)) + float32(Blue(c2))*a2) / 2.0)
// Combine the new values to an uint32 (ARGB), and return that
return RGBAToColorValue(r, g, b, 255)
}