broken-neees/lib/ppu/Sprite.js

A really broken NEEES emulator that introduces glitches and random bugs on purpose!

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _byte = _interopRequireDefault(require("../byte"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function _typeof(obj) { "@babel/helpers - typeof"; return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (obj) { return typeof obj; } : function (obj) { return obj && "function" == typeof Symbol && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }, _typeof(obj); }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, _toPropertyKey(descriptor.key), descriptor); } }
function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); Object.defineProperty(Constructor, "prototype", { writable: false }); return Constructor; }
function _toPropertyKey(arg) { var key = _toPrimitive(arg, "string"); return _typeof(key) === "symbol" ? key : String(key); }
function _toPrimitive(input, hint) { if (_typeof(input) !== "object" || input === null) return input; var prim = input[Symbol.toPrimitive]; if (prim !== undefined) { var res = prim.call(input, hint || "default"); if (_typeof(res) !== "object") return res; throw new TypeError("@@toPrimitive must return a primitive value."); } return (hint === "string" ? String : Number)(input); }
var TILE_SIZE_PIXELS = 8;
var PALETTE_FOREGROUND_START = 4;
var SPRITE_ATTR_PALETTE_BITS_START = 0;
var SPRITE_ATTR_PALETTE_BITS_SIZE = 2;
var SPRITE_ATTR_PRIORITY_BIT = 5;
var SPRITE_ATTR_HORIZONTAL_FLIP_BIT = 6;
var SPRITE_ATTR_VERTICAL_FLIP_BIT = 7;

/**
 * A sprite containing an id, position, height, a tile id and some attributes.
 * Sprites are defined by (y, tileId, attributes, x).
 *                                     76543210
 *                                     |||   ++- foregroundPaletteId
 *                                     ||+------ priority (0: in front of background, 1: behind background)
 *                                     |+------- horizontalFlip
 *                                     +-------- verticalFlip
 */
var Sprite = /*#__PURE__*/function () {
  function Sprite(ppu, id, x, y, is8x16, patternTableId, topTileId, attributes) {
    _classCallCheck(this, Sprite);
    this.ppu = ppu;
    this.id = id;
    this.x = x;
    this.y = y;
    this.is8x16 = is8x16;
    this.patternTableId = patternTableId;
    this.tileId = topTileId;
    this.attributes = attributes;
  }

  /**
   * Returns the tile id for an `insideY` position.
   * The bottom part of a 8x16 sprite uses the next tile index.
   */
  _createClass(Sprite, [{
    key: "tileIdFor",
    value: function tileIdFor(insideY) {
      var index = +(insideY >= TILE_SIZE_PIXELS);
      if (this.is8x16 && this.flipY) index = +!index;
      return this.tileId + index;
    }

    /** Returns whether it should appear in a certain `scanline` or not. */
  }, {
    key: "shouldRenderInScanline",
    value: function shouldRenderInScanline(scanline) {
      var diffY = this.diffY(scanline);
      return diffY >= 0 && diffY < this.height;
    }

    /** Returns the difference between a `scanline` and sprite's Y coordinate. */
  }, {
    key: "diffY",
    value: function diffY(scanline) {
      return scanline - this.y;
    }

    /** Returns the palette id of the sprite. */
  }, {
    key: "paletteId",
    get: function get() {
      return PALETTE_FOREGROUND_START + _byte.default.getBits(this.attributes, SPRITE_ATTR_PALETTE_BITS_START, SPRITE_ATTR_PALETTE_BITS_SIZE);
    }

    /** Returns whether the sprite is in front of background or not. */
  }, {
    key: "isInFrontOfBackground",
    get: function get() {
      if (!this.ppu.cpu.unbroken) {
        // [!!!]
        return true;
      }
      return !_byte.default.getBit(this.attributes, SPRITE_ATTR_PRIORITY_BIT);
    }

    /** Returns whether the sprite is horizontally flipped or not. */
  }, {
    key: "flipX",
    get: function get() {
      return _byte.default.getFlag(this.attributes, SPRITE_ATTR_HORIZONTAL_FLIP_BIT);
    }

    /** Returns whether the sprite is vertically flipped or not. */
  }, {
    key: "flipY",
    get: function get() {
      return _byte.default.getFlag(this.attributes, SPRITE_ATTR_VERTICAL_FLIP_BIT);
    }

    /** Returns the sprite height. */
  }, {
    key: "height",
    get: function get() {
      return this.is8x16 ? 16 : 8;
    }
  }]);
  return Sprite;
}();
exports.default = Sprite;