//This requires a linear mag filter
vec4 bicubic(sampler2DArray sampler, vec3 coords) {
  //Gather and process some basics (TODO: move to vertex shader)
  vec2 size = vec2(textureSize(sampler, int(textureQueryLod(sampler,coords.xy).x)).xy);
  vec2 invsize = 1./size;
  coords *= vec3(size,1);

  //Compute central coordinate of upper left texel of the nearest 4 texel patch
  vec2 texelCoords = floor(coords.xy-0.5)+0.5;
  vec2 f = coords.xy-texelCoords;

  //Powers
  vec2 f2 = f*f;
  vec2 f3 = f2 * f;

  //Compute weights
  vec2 w0 = f2 - 0.5 * (f3 + f);
  vec2 w1 = 1.5 * f3 - 2.5 * f2 + 1.;
  vec2 w3 = 0.5 * (f3-f2);
  vec2 w2 = 1. - w0 - w1 - w3;

  //Compute sampling coordinates
  vec2 s0 = w0 + w1;
  vec2 s1 = w2 + w3;

  vec2 f0 = w1 / s0;
  vec2 f1 = w3 / s1;

  vec2 t0 = texelCoords - 1. + f0;
  vec2 t1 = texelCoords + 1. + f1;
  t0*=invsize;
  t1*=invsize;

  return texture(sampler, vec3(t0,coords.z)) * s0.x * s0.y
  + texture(sampler, vec3(t1.x,t0.y,coords.z)) * s1.x * s0.y
  + texture(sampler, vec3(t0.x,t1.y,coords.z)) * s0.x * s1.y
  + texture(sampler, vec3(t1,coords.z)) * s1.x * s1.y;
}

void main()
{
if (UV.x>0.5){
vec3 tUV = UV-vec3(0.5,0,0);
vec2 size = vec2(textureSize(sampler, int(textureQueryLod(sampler,UV.xy).x)).xy);
  tUV.xy = floor(size*tUV.xy)+0.5;
  tUV.xy /= size;


fragColor = vec4(texture(sampler,tUV).rgb,tracer);
} else {
fragColor = vec4(bicubic(sampler,UV).rgb,tracer);
}
}