1 files changed, 63 insertions, 0 deletions
diff --git a/lib/camera.rb b/lib/camera.rb
new file mode 100644
index 0000000..f8721bb
--- /dev/null
+++ b/lib/camera.rb
@@ -0,0 +1,63 @@
+class Camera
+  def initialize(width = 100, aspect = 1.0, aliasing = 10)
+    @width = width
+    @aspect = aspect
+    @aliasing = aliasing
+
+    # Height
+    @height = (@width / @aspect).to_i
+    @height = @height < 1 ? 1 : @height
+
+    # Camera
+    c_focallength = 1.0
+    @c_centre = Point.new(0,0,0)
+
+    # Viewport
+    @v_height = 2.0
+    @v_width = @v_height * @width.to_f / @height
+    v_u = Vec3.new(@v_width, 0, 0)
+    v_v = Vec3.new(0, -@v_height, 0)
+
+    # Pixel deltas
+    @pd_u = v_u / @width
+    @pd_v = v_v / @height
+
+    # Upper left pixel
+    v_upperleft = @c_centre - v_u / 2 - v_v / 2 -
+                  Vec3.new(0, 0, c_focallength)
+    @p00_loc = v_upperleft + (@pd_u + @pd_v) / 2
+  end
+
+  def render(world)
+    start = Time.now.to_f
+
+    puts "P3"
+    puts "#{@width} #{@height}"
+    puts "255"
+
+    @height.times do |row|
+      $stderr.print "[GScanlines remaining: %4d" % (@height - row)
+      @width.times do |col|
+        p_colour = Colour.new
+        @aliasing.times do
+          p_colour += get_ray(row, col).colour(world)
+        end
+        puts (p_colour / @aliasing).to_ppm
+      end
+      puts
+    end
+
+    finish = Time.now.to_f
+    took = finish - start
+
+    $stderr.puts "[GDone. Took %4.2f seconds. " % took
+  end
+
+  def get_ray(row, col)
+    p_sample = @p00_loc +
+               @pd_u * (col + rand - 0.5) +
+               @pd_v * (row + rand - 0.5)
+
+    Ray.new(@c_centre, p_sample - @c_centre)
+  end
+end