Alice Yang CIS 565 Final Project

Ray Marching/Sphere Tracing  Starting from eye, proceed in small steps along ray.  Distance Estimator tells you how close you are to object.  When you are close to a certain threshold, stop.  Coloring by number of steps taken gives us cheap AO with no need for lights. Source:

Framework  The entire project is contained in a fragment shader written in GLSL  Code can be viewed and run on GLSL Sandbox (  Project built off of Paulo Falcao’s basic raymarch framework, extended to support a number of additional features

Domain Repetition Source: / /

Building Variation  Find “seed” constant for every building as input into random float generator  vec2 pos = vec2(ceil(p.x/c.x), ceil(p.z/c.z));

Building Geometry  Union operation: Add roofs and attics to tops of buildings  Subtraction operation: Windows and wall indents

Building Geometry: Windows  Create 2D cross and repeatedly subtract from building bodies  Insert inner structure to prevent building from looking hollow  “free” variation from random heights applied afterwards Source: / /

Textures  Mostly flat colors since project focuses on geometry  Half of the city samples from procedural brick texture.

 Constant values for brick and mortar color as well as brick size and brick percentage  After position is calculated, every other row is offset by half a brick’s width  Step function: If the fract(position) is less than brick percentage, use brick color. Otherwise use mortar color

Live Demo 