1 files changed, 74 insertions, 0 deletions
diff --git a/lib/vec3.rb b/lib/vec3.rb
new file mode 100644
index 0000000..6287813
--- /dev/null
+++ b/lib/vec3.rb
@@ -0,0 +1,74 @@
+class Vec3
+  def initialize(x = 0, y = 0, z = 0)
+    @x = x.to_f
+    @y = y.to_f
+    @z = z.to_f
+  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 to_s
+    "{#{@x}, #{@y}, #{@z}}"
+  end
+end
+
+class Point < Vec3; end
+
+class Colour < Vec3
+  def r; @x; end
+  def g; @y; end
+  def b; @z; end
+
+  def to_ppm
+    "%3d %3d %3d" % [(r * 255.999).to_i, (g * 255.999).to_i, (b * 255.999).to_i]
+  end
+end