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package main
import "math"
// Color in RGB, each val being between 0 and 1
type Color struct {
r, g, b float64
}
// ToPixel converts a 0-1 color to a 0-255 pixel
func (color Color) ToPixel() Pixel {
return Pixel{int(color.r * 255), int(color.g * 255), int(color.b * 255)}
}
// LinearBlend mixes two colors with a float param
func LinearBlend(color1 Color, color2 Color, param float64) Color {
return Color{
param*color1.r + (1.0-param)*color2.r,
param*color1.g + (1.0-param)*color2.g,
param*color1.b + (1.0-param)*color2.b,
}
}
// AttenuateColor multiplies two colors
func AttenuateColor(attenuation Color, color Color) Color {
return Color{
attenuation.r * color.r,
attenuation.g * color.g,
attenuation.b * color.b,
}
}
// RayColor finds a hit for a ray, scatters the ray and return the ray color
func RayColor(ray Ray, hitableList HitableList, depth int) Color {
if depth > MaxDepth {
return Color{0.0, 0.0, 0.0}
}
hit := hitableList.Hit(ray, TMin, TMax)
if hit.time > 0.0 {
scattered, attenuation := hit.material.Scatter(ray, hit)
return AttenuateColor(attenuation, RayColor(scattered, hitableList, depth+1))
}
param := 0.5 * (ray.direction.Unit().y + 1)
return LinearBlend(Color{0.5, 0.7, 1.0}, Color{1.0, 1.0, 1.0}, param)
}
// ColorMean computes the mean color of a color list
func ColorMean(colorList [RaysPerPixel]Color) Color {
length := float64(len(colorList))
meanColor := Color{}
for _, color := range colorList {
meanColor.r += color.r
meanColor.g += color.g
meanColor.b += color.b
}
meanColor.r /= length
meanColor.g /= length
meanColor.b /= length
return meanColor
}
// ColorMeanSquare is a more realistic color mean
func ColorMeanSquare(colorList [RaysPerPixel]Color) Color {
meanColor := ColorMean(colorList)
meanColor.r = math.Sqrt(meanColor.r)
meanColor.g = math.Sqrt(meanColor.g)
meanColor.b = math.Sqrt(meanColor.b)
return meanColor
}
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