Make texture image in a plane behave like background cover in CSS

backgroundCoverUv.glsl

vec2 backgroundCoverUv(vec2 screenSize, vec2 imageSize, vec2 uv) {
  float screenRatio = screenSize.x / screenSize.y;
  float imageRatio = imageSize.x / imageSize.y;
    
  vec2 newSize = screenRatio < imageRatio
    ? vec2(imageSize.x * screenSize.y / imageSize.y, screenSize.y)
    : vec2(screenSize.x, imageSize.y * screenSize.x / imageSize.x);
    
  vec2 newOffset = (screenRatio < imageRatio
    ? vec2((newSize.x - screenSize.x) / 2.0, 0.0)
    : vec2(0.0, (newSize.y - screenSize.y) / 2.0)) / newSize;
      
  return uv * screenSize / newSize + newOffset;
}