const drawParticles = this.regl({
      frag: `
        precision mediump float;
        uniform vec4 color;
        void main() {
          if (length(gl_PointCoord.xy - 0.5) > 0.5) {
           discard;
         }
          gl_FragColor = color;
        }`,

      vert: `
        precision lowp float;
        attribute vec2 position;
        uniform float pointSize;

        void main() {
          gl_PointSize = pointSize;
          gl_Position = vec4(position, 0, 1);
        }`,

      attributes: {
        position: this.positionBuffer,
      },

      uniforms: {
        // the batchId parameter gives the index of the command
        pointSize: 20,
        color: ({tick}, props, batchId) => [
          batchId > 15 ? 1 : 0,
          1,
          1,
          1,
        ],
      },

      primitive: 'points',

      count: 30,
    })