I just finished messing around with getting some glsl chromakey / green-screen shader code I found at shadertoy.com working in Izzy and thought I might share it here.

You can copy and paste the code below into a new GLSL actor. You can also use this user actor:Chromakey++.iua3

// this was converted into izziease from a bit of code "Created by jackdavenport in 2015-05-30" 
// it may be found here https://www.shadertoy.com/view...

// ISADORA_FLOAT_PARAM(thresh, thsh, 0.0, 1.0, 1.0, "Threshold amount.");

uniform float thresh;

// ISADORA_FLOAT_PARAM(padd, padd, 0.0, 1.0, 1.0, "Padding amount.");

uniform float padd;

// ISADORA_FLOAT_PARAM(red_color, red, 0.0, 1.0, 1.0, "Amount of red to key out.");
// ISADORA_FLOAT_PARAM(green_color, gren, 0.0, 1.0, 1.0, "Amount of green to key out.");
// ISADORA_FLOAT_PARAM(blue_color, blue, 0.0, 1.0, 1.0, "Amount of blue to key out.");

uniform float red_color;
uniform float green_color;
uniform float blue_color;

void mainImage ( out vec4 fragColor, in vec2 fragCoord )
{
vec2 uv = fragCoord.xy / iResolution.xy;
    
    vec4 greenScreen = vec4(red_color, green_color, blue_color, 1.0);
    vec4 color = texture(iChannel0, uv);
    
    vec3 diff = color.xyz - greenScreen.xyz;
    float fac = smoothstep(thresh-padd,thresh+padd, dot(diff,diff));
    
    color = mix(color, texture(iChannel1, uv), 1.-fac);
fragColor = color;
}