Separate glitch effect and logic

[anissen]

Right now, the glitch effect is tied into some logic that handles the chance of glitches. In my use case, I need to be able to trigger the glitches myself. So I propose to separate the glitch effect and the "glitch chance"-logic into separate classes.

[steverichey]

So you'd like to be able to trigger the glitch by, for example, calling RenderLayer.triggerGlitch()?

[anissen]

Yeah, that was the idea. E.g. having a RenderLayer.randomGlitch() and RenderLayer.glitch(x, y, strength, duration) sort of like FlxG.camera.shake(). You could then have a new GlitchLayer(glitchChance, ...) that uses RenderLayer.

For my purposes, I went the shader way (possible with the new postprocessing support in HaxeFlixel). The following fragment shader make a nice glitchy effect:

float rand(vec2 co) {
    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}

void main() {
    // (...)
    if (rand(vec2(1.0 - uTime, sin(uTime))) > 0.98) { 
       shift = 0.1 * rand(vec2(uTime, uTime)); 
    }
    col.r = texture2D(uImage0, vec2(uv.x + shift, uv.y)).x;
    col.g = texture2D(uImage0, vec2(uv.x, uv.y)).y;
    col.b = texture2D(uImage0, vec2(uv.x - shift, uv.y)).z;
    // (...)
}