Core.java

package com.dongbat.example.game;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import io.anuke.gif.GifRecorder;

public class Core extends ApplicationAdapter {

  private static final int NUM_VERTICES = 100000;
  private Mesh mesh;
  private ShaderProgram shader;
  private float time = 0;
  
  private SpriteBatch batch;
  private GifRecorder gifRecorder;

  @Override
  public void create() {
    mesh = new Mesh(true, NUM_VERTICES, 0, new VertexAttribute(Usage.Generic, 1, "vertexId"));
    float[] ids = new float[NUM_VERTICES];
    for (int i = 0; i < NUM_VERTICES; i++) {
      ids[i] = i;
    }

    mesh.setVertices(ids);
    shader = new ShaderProgram(Gdx.files.internal("test.vs.glsl"), Gdx.files.internal("test.fs.glsl"));
    ShaderProgram.pedantic = false;

    if (shader.getLog().length() != 0) {
      System.out.println(shader.getLog());
    }
    
    batch = new SpriteBatch();
    gifRecorder = new GifRecorder(batch);
  }

  @Override
  public void render() {
    Gdx.gl.glClearColor(0, 0, 0, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);
    
    Gdx.gl.glEnable(GL20.GL_DEPTH_TEST);
    Gdx.gl.glEnable(0x8642);

    time += Gdx.graphics.getDeltaTime() * 2;

    shader.begin();
    shader.setUniformf("time", time);
    shader.setUniformf("vertexCount", NUM_VERTICES);
    shader.setUniformf("resolution", Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    mesh.render(shader, GL20.GL_TRIANGLES);
    shader.end();
    
    gifRecorder.update();
  }

  @Override
  public void dispose() {
    mesh.dispose();
    shader.dispose();
    batch.dispose();
  }
}

test.fs.glsl

#ifdef GL_ES
#define LOWP lowp
precision mediump float;
#else
#define LOWP
#endif

varying vec4 v_color;

void main() {
  gl_FragColor = v_color;
}

test.vs.glsl

attribute float vertexId;

uniform float time;
uniform vec2 resolution;
uniform float vertexCount;

varying vec4 v_color;

void main() {
  ...
}