CS 6620 - Fall 2017 - Ray Tracing for Graphics

Project 10 - Soft Shadows and Glossy Surfaces

In this project we will add support for soft shadows and glossy reflections/refractions to our ray tracers.

Requirements

Implement soft shadows for area lights.
Implement glossy reflections and refractions.
Render images showing your results with different parameters.

XML Scene Format

In the XML scene format we specify area shadows by adding a "size" value to point lights. This size value effectively converts the point light to a spherical area light.

<light type="point" name="pointLight">
	<intensity value="1.0"/>
	<position x="-50" y="-100" z="50"/>
	<size value="5.0"/>
</light>

We specify glossy reflections/refractions by adding a "glossiness" value for the "reflection" or "refraction" tag of the Blinn material. The glossiness value determines the maximum shift in degrees from the perfect refection or refraction direction. If the glossiness is not specified, it should be regarded as zero, which means no glossy reflections/refractions. Notice that the "glossiness" value for the "reflection" tag is separate from the "glossiness" of the Blinn shading.

<material type="blinn" name="ground">
   <diffuse r="0.3" g="0.3" b="0.3"/>
   <specular value="0.1"/>
   <glossiness value="50"/>
	<reflection value="0.5" glossiness="0.01"/>
	<refraction index="1.52" value="0.5" glossiness="0.1"/>
</material>

Source Code

The following source code files are provided to help you with this and upcoming projects. You are not required to use them, but it is highly recommened that you use them and refrain from modifying them. Some of these files include additional code as compared to the same files in the previous project, so make sure to download them all again.

xmlload.cpp: Includes the LoadScene() function that parses a given scene XML file using the TinyXML library.
lights.h: Includes the descriptions of the light classes used by the xmlload.cpp file. Notice that the implementation of PointLight::Illuminate() method is removed.
materials.h: Includes the description of the Blinn material class used by the xmlload.cpp file. This version has new parameters for glossy reflections and refractions.

Test Scenes

The following scene files are provided to help you test your implementation. You can also prepare other scenes to show your work.

Test scene: Four reflective balls with different glossiness values, one reflective teapot, and one refractive glossy ball in front of a wall, illuminated by an area light.

Optional Feature Suggestions

Implement area lights for shading.
Use a Quasy Monte-Carlo sequence for glossy reflections/refractions as well as area lights.

References

[Cook et al. 1984] Robert L. Cook, Thomas Porter, and Loren Carpenter. 1984. Distributed ray tracing. In Proceedings of the 11th annual conference on Computer graphics and interactive techniques (SIGGRAPH '84), Hank Christiansen (Ed.). ACM, New York, NY, USA, 137-145.

Student Project Pages