README.md

Custom fragment shaders

From ShaderToy

I am including this README so I don't directly distribute others' works, but I will point out some necessary tweaks to get this playground repo to work with them:

0) Prerequisites

Please note this is not an extremely robust solution, many things are not fully functional. Notably including iChannels (often used for audio/textures). But for relatively simple shaders this works well enough.

1) Copy source from shadertoy

Here are some great shaders that I have successfully managed to port to this codebase:

Title	Creator	Link
Geomechanical	Bers	https://www.shadertoy.com/view/MdcXzn
simple 2d animation	naxius	https://www.shadertoy.com/view/WdsGRl
fractal pyramid	bradjamesgrant	https://www.shadertoy.com/view/tsXBzS
Mandelbulb	EvilRyu	https://www.shadertoy.com/view/MdXSWn
SeaScape	TDM	https://www.shadertoy.com/view/Ms2SD1
Happy Jumping	iq	https://www.shadertoy.com/view/3lsSzf
Raymarching - Primitives	iq	https://www.shadertoy.com/view/Xds3zN

You can simply paste the content into a new .glsl file in this shaders/main/ directory.

2) Add to the beginning of the file

#version 330 core

layout(location = 0) out vec4 fragColor;
uniform vec2 iResolution;
uniform float iTime;
uniform vec2 iMouse;
uniform int iFrame;

This respects the primary input/output mechanisms that ShaderToy uses in their API.

3) Replace mainImage

# replace
void mainImage( out vec4 fragColor, in vec2 fragCoord )

# with this
vec4 expensive_main()

# and add at the bottom of the function:
return fragColor;

(Note, the fragColor variable was newly declared at the top of the file as described in #2)

4) Replace fragCoord with gl_FragCoord.xy

Replace all instances of fragCoord (a vec2) with gl_FragCoord.xy (originally a vec4), note that the .xy is swizzling (accessing the xy components of the vector) the vec4 to convert it to a vec2. In cases where fragCoord.x is used, you can instead replace with gl_FragCoord.x to follow the sizzling.

5) [If necessary] Refactor #if

In a lot of cases I ran into issues with #if declarations in the .glsl files, so I simply commented them out if they casued problems.

6) Point to the new file in the params

Finally, make sure the fragment_shader variable in params/params.ini (or whatever param file you are using) correctly points to the new .glsl file you added.

fragment_shaders=../src/shaders/new_shader_here.glsl