func hexToColorNRGBA(hex string) color.NRGBA {
c := color.NRGBA{}
getIntensity := func(str string) uint8 {
if u, err := hexToUint8(str); err == nil {
return u
}
return 0
}
if len(hex) >= 6 {
c.R = getIntensity(hex[0:2])
c.G = getIntensity(hex[2:4])
c.B = getIntensity(hex[4:6])
}
if len(hex) == 8 {
c.A = getIntensity(hex[6:8])
} else {
c.A = 255
}
return c
}
func writeImagePng(filename string, pixels []float32, xres, yres int) {
outImage := image.NewNRGBA(image.Rect(0, 0, xres, yres))
to_byte := func(v float32) uint8 {
// apply gamma and convert to 0..255
return uint8(Clamp(255.0*math.Pow(float64(v), 1.0/2.2), 0.0, 255.0))
}
for y := 0; y < yres; y++ {
for x := 0; x < xres; x++ {
var fcolor color.NRGBA
fcolor.R = to_byte(pixels[3*(y*xres+x)+0])
fcolor.G = to_byte(pixels[3*(y*xres+x)+1])
fcolor.B = to_byte(pixels[3*(y*xres+x)+2])
fcolor.A = 0xff
outImage.Set(x, y, fcolor)
}
}
f, err := os.Create(filename)
defer f.Close()
if err != nil {
Error("Error writing PNG \"%s\"", filename)
} else {
png.Encode(f, outImage)
}
}
// render one row of pixels by calculating a colour for each pixel.
// The image pixel row number is r. Fill the pixel colour into the
// image after the colour has been calculated.
func (r row) render(rt *rtrace, a, b, c lin.V3, img *image.NRGBA, seed *uint32) {
rgba := color.NRGBA{0, 0, 0, 255}
t, v1, v2 := lin.NewV3(), lin.NewV3(), lin.NewV3() // temp vectors.
colour, orig, dir := lin.NewV3(), lin.NewV3(), lin.NewV3()
for x := (rt.iw - 1); x >= 0; x-- {
colour.SetS(13, 13, 13) // Use a very dark default colour.
// Cast 64 rays per pixel for blur (stochastic sampling) and soft-shadows.
for cnt := 0; cnt < 64; cnt++ {
// Add randomness to the camera origin 17,16,8
t.Scale(&a, rnd(seed)-0.5).Scale(t, 99).Add(t, v1.Scale(&b, rnd(seed)-0.5).Scale(v1, 99))
orig.SetS(17, 16, 8).Add(orig, t)
// Add randomness to the camera direction.
rnda := rnd(seed) + float64(x)
rndb := float64(r) + rnd(seed)
dir.Scale(t, -1)
dir.Add(dir, v1.Scale(&a, rnda).Add(v1, v2.Scale(&b, rndb)).Add(v1, &c).Scale(v1, 16))
dir.Unit()
// accumulate the colour from each of the 64 rays.
sample := rt.sample(*orig, *dir, seed)
colour = sample.Scale(&sample, 3.5).Add(&sample, colour)
}
// set the final pixel colour in the image.
rgba.R = byte(colour.X) // red
rgba.G = byte(colour.Y) // green
rgba.B = byte(colour.Z) // blue
img.SetNRGBA(rt.iw-x, int(r), rgba)
}
}
func setRandomBrightness(c *color.NRGBA, max uint8) {
minc := min3(c.R, c.G, c.B)
maxc := max3(c.R, c.G, c.B)
if maxc > max {
return
}
n := rand.Intn(int(max-maxc)) - int(minc)
c.R = uint8(int(c.R) + n)
c.G = uint8(int(c.G) + n)
c.B = uint8(int(c.B) + n)
}