RAYMARCHING AN INFINITE CITY

Alice YangCIS 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: http://blog.hvidtfeldts.net/index.php/2011/06/distance-estimated-3d-fractals-part-i/

Framework The entire project is contained in a fragment

shader written in GLSL Code can be viewed and run on GLSL

Sandbox (http://glsl.heroku.com/e#2306.2) Project built off of Paulo Falcao’s basic

raymarch framework, extended to support a number of additional features

Domain Repetition

Source: http://www.iquilezles.org/www/articles/distfunctions/distfunctions.htm /

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: http://www.iquilezles.org/www/articles/menger/menger.htm /

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 http://glsl.heroku.com/e#2306.2