#ifdef GL_ES
precision mediump float;
#endif

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

//In codelife, you need to click the + button by parameters, navigate to 'built-in>input', and add 'midi channel'
//At the time of writing this, the default name is midi1. I changed it to u_midi
uniform sampler2D u_midi;


//this function takes a midi offset and turns it into coordinates for the texture/sampler
//the KodeLife examples use ints, but float seemed to be required in my case
//values are divided by 32. because the midi channel resolution is 32, but texture2D requires 0.-1.
vec2 midiCoord(float offset)
{
    float x = mod(offset,32.);
    float y = offset / 32.;
    return vec2(x,y)/32.;
}

void main() {
    //st represents the position from 0. to 1. on the x and y axes where the pixel lives
    //this convention is adopted from thebookofshaders.com
    vec2 st = gl_FragCoord.xy/u_resolution;
    
    //the 3 at the beginning takes you to the midi continuous controllers
    //21, 22, and 23 are the addresses for the continuous controllers I am using for r, g, and b
    //I found these using components, the configuration software for my novation controller
    
    float ccr = 3. * 127. + 21.;
    float ccg = 3. * 127. + 22.;
    float ccb = 3. * 127. + 23.;
    
    //now we can use texture2D and midiCoord to pull r, g, and b values fro the 4th dimension of the sample
    float r = texture2D(u_midi,midiCoord(ccr)).w;
    float g = texture2D(u_midi,midiCoord(ccg)).w;
    float b = texture2D(u_midi,midiCoord(ccb)).w;
    

    gl_FragColor = vec4(r,g,b,1.);
}