Herbert David Young

Raytracer

--------------------------------------------------------------------------------

	-YoungRay-

--------------------------------------------------------------------------------
 Features:

  -I included several example YoungRay Scene files: *.yrs
 (and the output *.ppm if you do not want to trace them)
  -Command line options: input_scene width height output_image
  -Relatively fast rendering (only a couple minutes for a large scene with a
 dozen objects and 81 lights, or several seconds for a small scene)
  -Supports a scene description language for input, which is flexable for white
 space, and optional parameters.  Also, the parser generates useful error
 messages in the case of incorrect syntax.  Here is the correct syntax:
	global_settings {
		background_rgb = (float,float,float)
		max_trace = int
	}
	camera {
		position = <float,float,float>
		look_at  = <float,float,float>
		image_plane_distance = float
		image_plane_height = float
		image_plane_width = float
	}
	light_source
	{
		position = <float,float,float>
		ambient_rgb = (float,float,float)
		diffuse_rgb = (float,float,float)
		specular_rgb = (float,float,float)
// the area_light portion is optional
		area_light {
			vec1 = <float,float,float>
			num1 = int
			vec2 = <float,float,float>
			num2 = int
		}
	}
// multiple light statements optional
	plane {
		position = <float,float,float>
		normal = <float,float,float>
		texture = texture_name
// bounding shapes are optional
		bounding_box {
			x_min = float
			x_max = float
			y_min = float
			y_max = float
			z_min = float
			z_max = float
		}

		bounding_sphere {
			position = <float,float,float>
			radius = float
		}
	}
	sphere {
		position = <float,float,float>
		radius = float
		texture = texture_name
// bounding shapes are optional
	}
// multiple objects (sphere,plane) optional

  Multiple lights and objects are allowed, as long as the maximums are not
 reached (100 objects, and 81 lights).

  -Supported textures are:
	Yellow_Plastic
	Blue_Plastic
	Rainbow
	Wood
	Checker
	Glass
	Marble
	Mirror
	Metal

	Sun
	Mercury
	Venus
	Earth
	Mars
	Jupiter
	Saturn
	Saturn_Rings
	Uranus
	Neptune
	Pluto

  -New textures can be added by simple creating new subclasses of the Texture
 class, and defining the functions which specify colour and lighting attributes.

  -New objects can be created by subclassing the Object class, and defining
 certain functions, such as getNormal() and getIntersection().

  -All objects support optional bounding_box or bounding_sphere which allow for
 interesting new shapes, and possible future updates to the algorithm for
 efficiency

  -Textures and lighting work correctly inside/outside, treating every object
 as a surface.

  -Shadows are filtered when passing through transparent objects, based on each
 objects transparency.

  -Images are output into P3 (ascii) ppm files, with 256 shades of red, green,
 and blue.  The resolution is specified by parameters two and three in the
 command line, and the image name is the fourth parameter.

  -Area lights are supported: when area_light is defined inside of a light
 source, the raytracer will simulate this by creating n1xn2 lights on a grid,
 specified by vec1 and vec2, centred around the light's position.  Remember that
 because there are a maximum of 81 lights in a scene, a 9x9 area light is
 the maximum grid size.  Area lights simulate more realistic shadows by blurring
 the line between full shadow and full light.

  -max_trace specifies the maximum depth of ray recursion, and background_rgb
 specifies the colour given to rays which do not intersect anything in the
 scene.

  -Parsing and raytracing progress is outputted to the screen to keep the user
 notified.  After tracing is complete, statistics are output to the console,
 which include:
	number of reflected, refracted, and shadow rays
	total number of lights, objects, rays, pixels, and time to complete
	average number of rays/pixel, rays/second, and pixels/second

  -Time to create raytracer: 51 hours

--------------------------------------------------------------------------------

  -The code I used to create "Solar System.mpg" was copied to MainAnim.cpp.  I
 hardcoded the anmation since I did not have time to write animation-ability
 into my scene description language.  MainAnim.cpp output 96 .ppm files which
 I used serveral utilities on, to convert to .bmp, then to .avi, then to .mpg.
 I also included a couple of sample .ppm images in case the viewer does not
 want to wait to trace a sample scene.
  -To view the images output by YoungRay, use xview file.ppm

  -scene1.yrs demostrates:
    reflection, refraction, and most textures
  -scene2.yrs:
    background colour, object clipping (bounding_box, bounding_sphere)
  -scene3.yrs:
    mirror and metal textures, and area_light
    the soft shadows of the metal and wood spheres are because of a
    9x9 area_light