pixijs v4.6.0: 実際の画像の大きさに合わせてfilterのshader側でuvを[0-1]に収めるための関数

applyMappedMatrixFilter.js

// 実際の画像の大きさに合わせてfilterのshader側でuvを[0-1]に収めるための関数
// 参考: http://www.html5gamedevs.com/topic/23790-uv-in-filters/

export default (vert, frag, uniforms = {}) => {
  if (!uniforms.mappedMatrix) {
    uniforms.mappedMatrix = {
      type: 'mat3',
      value: new PIXI.Matrix(),
    };
  }
  const filter = new PIXI.Filter(vert, frag, uniforms);
  filter.apply = function apply(filterManager, input, output) {
    filterManager.calculateNormalizedScreenSpaceMatrix(this.uniforms.mappedMatrix);
    filterManager.applyFilter(this, input, output);
  };

  return filter;
};