Java version

Shadertoy_VoronoiDistances.java

import processing.core.*;
import java.nio.ByteBuffer;
import com.jogamp.opengl.GL2;
import com.thomasdiewald.pixelflow.java.DwPixelFlow;
import com.thomasdiewald.pixelflow.java.dwgl.DwGLTexture;
import com.thomasdiewald.pixelflow.java.imageprocessing.DwShadertoy;

public class Shadertoy_VoronoiDistances extends PApplet {

    /**
     *
     * PixelFlow | Copyright (C) 2017 Thomas Diewald - www.thomasdiewald.com
     *
     * https://github.com/diwi/PixelFlow.git
     *
     * A Processing/Java library for high performance GPU-Computing. MIT
     * License: https://opensource.org/licenses/MIT
     *
     */
    //
    // Shadertoy Demo:   https://www.shadertoy.com/view/ldl3W8
    // Shadertoy Author: https://www.shadertoy.com/user/iq
    //
    DwPixelFlow context;
    DwShadertoy toy;
    DwGLTexture tex0 = new DwGLTexture();

    public void settings() {
        size(1280, 720, P2D);
        smooth(0);
    }

    public void setup() {
        surface.setResizable(true);

        context = new DwPixelFlow(this);
        context.print();
        context.printGL();

        toy = new DwShadertoy(context, "data/VoronoiDistances.frag");

        // create noise texture
        int wh = 256;
        byte[] bdata = new byte[wh * wh * 4];
        ByteBuffer bbuffer = ByteBuffer.wrap(bdata);
        for (int i = 0; i < bdata.length;) {
            bdata[i++] = (byte) random(-127, 127);
            bdata[i++] = (byte) random(-127, 127);
            bdata[i++] = (byte) random(-127, 127);
            bdata[i++] = (byte) -1;
        }
        System.out.println(Byte.toUnsignedInt(bdata[3]));
        tex0.resize(context, GL2.GL_RGBA8, wh, wh, GL2.GL_RGBA, GL2.GL_BYTE, GL2.GL_LINEAR, GL2.GL_MIRRORED_REPEAT, 4, 1, bbuffer);
        frameRate(60);
    }

    public void draw() {

        toy.set_iMouse(mouseX, height - 1 - mouseY, mouseX, height - 1 - mouseY);
        toy.set_iChannel(0, tex0);
        toy.apply(this.g);

        String txt_fps = String.format(getClass().getSimpleName() + "   [size %d/%d]   [frame %d]   [fps %6.2f]", width, height, frameCount, frameRate);
        surface.setTitle(txt_fps);
    }

    static public void main(String[] passedArgs) {
        String[] appletArgs = new String[]{"Shadertoy_VoronoiDistances"};
        if (passedArgs != null) {
            PApplet.main(concat(appletArgs, passedArgs));
        } else {
            PApplet.main(appletArgs);
        }
    }
}