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1 – Raymarching, Distance functions

Some time ago, I found this page: Modeling with distance functions by GLSL wizard iq. This page contains many ready-to-use functions to create primitives in GLSL. Ready-to-use functions… only if you have a pixel shader ready to use them. Actually, all these functions are intended for raymarching with distance fields. Raymarching is ray casting with large steps along the ray and a distance field function returns the minimum distance to any surface in a scene from any point. More details can be found on this iq’s presentation: Rendering Worlds with Two Triangles.

The aim of this article is to provide the basic GLSL framework to use these cool distance functions as well as the use of these functions.

Raymarching is one of the secrets behind those amazing demos.



Raymarching Demos I used GLSL Hacker to code and play with raymarching (I coded with version 0.5.0). You will find all ready-to-hack demos in GLSL Hacker Code Sample Pack in the GLSL_Raymarching/ folder. How to run the demos: start GLSL Hacker and load each demo file (*.xml files). That’s all. To tweak raymarching shaders, live coding is an useful tool (see HERE and HERE).

All the shaders in this article are not linked to GLSL Hacker. You can use them in any application that can load GLSL shaders and of course in WebGL tools like Shadertoy or GLSL Sandbox.







In all GLSL Hacker demos, I set the VSYNC to ON to limit the framerate because NVIDIA drivers do not like some raymarching shaders:



To disable the vertical synchronisation, just replace the following line in INIT scripts:

gh_renderer.set_vsync(1)

by

gh_renderer.set_vsync(0)

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