random number

[radio412]

I am new to gpu.js.
In order to learn how to effectively use gpu.js I selected this function to port to a gpu.js kernel as it seemed appropriate. It simply creates a noise field.

     var
     x, y,
     number,
     opacity = opacity || .2;
     ctx = canvas.getContext('2d');
     for ( x = 0; x < canvas.width; x++ ) {
        for ( y = 0; y < canvas.height; y++ ) {
           n = Math.floor( Math.random() * 60 );
           ctx.fillStyle = "rgba(" + n + "," + n + "," + n+ "," + opacity + ")";
           ctx.fillRect(x, y, 1, 1);
        }
     }

I do not understand how to implement a random value for n. I do understand I can color any pixel of the canvas using this.color() with setGraphical(true).

Do I need to populate an array with random values and send it to the kernel as a parameter?

[robertleeplummerjr]

For the time being, use Math.random() in js, and not inside the gpu.js kernel. I'll resolve this soon.

[robertleeplummerjr]

For the time being, if it was absolutley needed, you could do something like:

var gpu = new GPU();
var myFunction = gpu.createKernel(function() {
  return Math.random();
});
myFunction.addGLSLFunction('random', `highp float random(vec2 co)
{
    highp float a = 12.9898;
    highp float b = 78.233;
    highp float c = 43758.5453;
    highp float dt= dot(co.xy ,vec2(a,b));
    highp float sn= mod(dt,3.14);
    return fract(sin(sn) * c);
}`);

I exposed a means of defining a glsl function directly, but as for the random function itself, there are many examples far and wide, but none that I feel are particularly noteworthy. The example I got from: http://byteblacksmith.com/improvements-to-the-canonical-one-liner-glsl-rand-for-opengl-es-2-0/