A halftone shader in GLSL, adapted from Stefan Gustavson's work here. Bilinear texture sampling and minification are left up to the user to implement (see steps 5 and 9 in Gustavson's tutorial).
For anti-aliasing, you should enable standard derivatives at the top of your shader, before requiring this module.
precisionhighpfloat;
#ifdef GL_OES_standard_derivatives
#extension GL_OES_standard_derivatives : enable
#endifvaryingvec2 uv;
uniformvec2 iResolution;
uniformsampler2D u_sampler;
#pragma glslify: halftone = require('glsl-halftone')
void main() {
//sample from texture; optionally using manual bilinear filteringvec4 texcolor =texture2D(u_sampler, uv);
//aspect corrected texture coordinatesvec2 st = uv;
st.x *= iResolution.x / iResolution.y;
//apply halftone effectgl_FragColor.rgb = halftone(texcolor.rgb, st);
gl_FragColor.a =1.0;
}
Applies a halftone effect to the given texture color using the uv coordinates. Higher frequency (default 30.0) leads to more tiling and smaller circles. Returns the RGB result.
See stackgl/contributing for details.
The halftone effect is public domain, by Stefan Gustavson. This also uses Ashima's glsl-noise, which is MIT.
The rest of the adaptation is MIT, see LICENSE.md for details.