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class Vec3
def initialize(x = 0.0, y = 0.0, z = 0.0)
@x = x
@y = y
@z = z
end
attr_reader :x, :y, :z
def +(oth)
self.class.new(@x + oth.x, @y + oth.y, @z + oth.z)
end
def -@
self.class.new(-@x, -@y, -@z)
end
def -(oth)
self + -oth
end
def *(oth)
if oth.is_a?(Vec3)
self.class.new(@x * oth.x, @y * oth.y, @z * oth.z)
else
self.class.new(@x * oth, @y * oth, @z * oth)
end
end
def /(oth)
self * (1.0 / oth)
end
def dot(oth)
v = self * oth
v.x + v.y + v.z
end
def cross(oth)
self.class.new(
@y * oth.z - @z * oth.y,
@z * oth.x - @x * oth.z,
@x * oth.y - @y * oth.x
)
end
def mag_sqr
@x ** 2 + @y ** 2 + @z ** 2
end
def mag
mag_sqr ** 0.5
end
def unit
self / mag
end
def reflect(normal)
self - normal * dot(normal) * 2
end
def refract(normal, etaratio)
costheta = [(-self).dot(normal), 1.0].min
rout_perp = (self + normal * costheta) * etaratio
rout_parr = normal * -((1.0 - rout_perp.mag_sqr).abs ** 0.5)
rout_perp + rout_parr
end
def in_unit?
mag_sqr < 1
end
def near_zero?(s = 1e-8)
@x.abs < s && @y.abs < s && @z.abs < s
end
def to_s
"{#{@x}, #{@y}, #{@z}}"
end
def self.random(min: -1.0, max: 1.0, dimensions: 3)
interval = Interval.new(min, max)
self.new(
dimensions >= 1 ? interval.sample : 0,
dimensions >= 2 ? interval.sample : 0,
dimensions >= 3 ? interval.sample : 0
)
end
def self.random_in_unit(normal: nil, dimensions: 3)
p = nil
while p.nil?
c = self.random(dimensions: dimensions)
p = c.unit if c.in_unit?
end
normal.nil? || p.dot(normal) > 0 ? p : -p
end
end
class Point < Vec3; end
class Colour < Vec3
def r; @x; end
def g; @y; end
def b; @z; end
def gamma(gma = 2)
Colour.new(
r > 0 ? r ** (1.0 / gma) : r,
g > 0 ? g ** (1.0 / gma) : g,
b > 0 ? b ** (1.0 / gma) : b
)
end
def clamp(interval)
Colour.new(
interval.clamp(r),
interval.clamp(g),
interval.clamp(b)
)
end
def to_ppm
g_space = gamma.clamp(Interval.new(0.0, 0.999))
"%3d %3d %3d" % [
(g_space.r * 256).to_i,
(g_space.g * 256).to_i,
(g_space.b * 256).to_i
]
end
end
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