export const fragmentSource = `
  precision highp float;
  uniform sampler2D uTexture;
  uniform float uBlocksize;
  uniform float uStepW;
  uniform float uStepH;
  varying vec2 vTexCoord;
  void main() {
    float blockW = uBlocksize * uStepW;
    float blockH = uBlocksize * uStepH;
    int posX = int(vTexCoord.x / blockW);
    int posY = int(vTexCoord.y / blockH);
    float fposX = float(posX);
    float fposY = float(posY);
    vec2 squareCoords = vec2(fposX * blockW, fposY * blockH);
    vec4 color = texture2D(uTexture, squareCoords);
    gl_FragColor = color;
  }
`;