1 files changed, 79 insertions, 0 deletions
diff --git a/rtiaw b/rtiaw
new file mode 100755
index 0000000..5fb7e5a
--- /dev/null
+++ b/rtiaw
@@ -0,0 +1,79 @@
+#!/usr/bin/env ruby
+
+start = Time.now.to_f
+
+$LOAD_PATH.unshift File.dirname(__FILE__) + '/lib'
+require 'interval'
+require 'vec3'
+require 'ray'
+require 'hittable'
+
+def ray_colour(ray, world)
+  if rec = world.hit(ray, Interval.new(0, Float::INFINITY))
+    return (Colour.new(1,1,1) + rec.normal) * 0.5
+  end
+
+  unit_dir = ray.direction.unit
+  a = (unit_dir.y + 1) / 2
+  Colour.new(1.0, 1.0, 1.0) * (1-a) + Colour.new(0.5, 0.7, 1.0) * a
+end
+
+# Define image
+width = 400
+aspect = 16.0 / 9
+max = 255
+
+# Calculate height
+height = (width / aspect).to_i
+height = height < 1 ? 1 : height
+
+# World
+world = Hittables.new
+world << Sphere.new(0,0,-1, 0.5)
+world << Sphere.new(0,-100.5,-1, 100)
+
+# 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 -
+              Vec3.new(0, 0, c_focallength) -
+              v_u / 2 -
+              v_v / 2
+p_00loc = v_upperleft +
+          (pd_u + pd_v) / 2
+
+puts <<-EOH
+P3
+#{width} #{height}
+#{max}
+EOH
+
+height.times do |row|
+  $stderr.print "[GScanlines remaining: %4d" % (height - row)
+  width.times do |col|
+    p_centre = p_00loc + (pd_u * col) + (pd_v * row)
+    ray_dir = p_centre - c_centre
+    ray = Ray.new(c_centre, ray_dir)
+
+    p_colour = ray_colour(ray, world)
+    puts p_colour.to_ppm
+  end
+  puts
+end
+
+finish = Time.now.to_f
+took = finish - start
+
+$stderr.puts "[GDone. Took %4.2f seconds. " % took