Vertex shader with 4 texture (tiling satellite image)

gistfile1.txt

precision mediump float;

uniform sampler2D satellite0;
uniform sampler2D satellite1;
uniform sampler2D satellite2;
uniform sampler2D satellite3;
uniform sampler2D elevation;

varying vec2 vUv;

void main() {
  if (vUv.x <= 0.5 && vUv.y >= 0.5) {
    vec2 mappedUv = vUv / 0.5 - vec2(0, 1.);
    gl_FragColor = texture2D(satellite0, mappedUv);
  }
  if (vUv.x >= 0.5 && vUv.y >= 0.5) {
    vec2 mappedUv = vUv / 0.5 - vec2(1., 1.);
    gl_FragColor = texture2D(satellite1, mappedUv);
  }
  if (vUv.x >= 0.5 && vUv.y <= 0.5) {
    vec2 mappedUv = vUv / 0.5 - vec2(1, 0.);
    gl_FragColor = texture2D(satellite3, mappedUv);
  }
  if (vUv.x <= 0.5 && vUv.y <= 0.5) {
    gl_FragColor = texture2D(satellite2, vUv / 0.5);
  }
}