text: export default {
    preparePixelIndex: function() {
      this.pixelIndex = new Array()
  
      for (let i = 0; i < this.width * this.height; i++) {
        const x = i & (this.width - 1)
        const y = (i - (i & (this.width - 1))) / this.width
        this.pixelIndex[i] = [x, y]
      }
    },
  
    setScreenIndex: function(isVerticalMirror) {
      if (isVerticalMirror) {
        this.screenIndex = [0, 1, 0, 1]
      } else {
        this.screenIndex = [0, 0, 1, 1]
      }
    }
  }
  