Implement ASCII Effect

[LucaArgentieri]

Is your feature request related to a problem?

I have implemented the Ascii effect of threejs but it is heavy in some cases and not compatible with other postprocessing effects because of its operation.

Describe the solution you'd like

I tried this Ascii library and it seems to work quite well, certainly can be improved but is a good starting point for including it in the postprocessing library.

composer = new EffectComposer(renderer);
composer.addPass(new RenderPass(scene, camera));


const asciiEffect = new ASCII({
 fontSize: 40,
 cellSize: 10,
 invert: false,
 color: true,
 characters: ` .:,'-^=*+?!|0#X%WM@`
});

composer.addPass(new EffectPass(camera, new GlitchEffect()));
composer.addPass(new EffectPass(camera, asciiEffect));

[vanruesc]

Hi, that's a nice effect!

Feel free to send a PR for v6 as a starting point. I'll help with the refactoring.