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POMost efficient way of using multidimensional array indexers
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copied!<p>Say you have a 2D grid of tiles (This is for a 2D tile based game), most tiles occupy 1 spot, however some larger "objects" can fill in multiple spots. I use an indexer on my array to automatically "refer" these objects to their base tile. So If I have a 2x2 object at 3,4, and I access 4,4, it will automatically redirect and get the tile at 3,4. However I can specify an argument to go around this functionality in the event that I need to get the exact tile. (Better explanation on <a href="https://gamedev.stackexchange.com/q/33967/13911">my old question</a> on GameDev about this)</p> <p>Another way to look at it is a door object in the game world, the user can click anywhere on it to open it, but each individual part can contain other properties, like different backgrounds and lighting values.</p> <p>Note I am just a hobbyist programmer, so this may not be right (and why I am seeking your advice) Each "extra large" tile will store a reference to it's base tile in the form of a <code>X,Y</code> position (Should this instead be a reference to the actual object in memory?)</p> <pre><code>public class TileWrapper { public int Width = 0; public int Height = 0; private Tile[] tiles; //Backing Store public TileWrapper() { tiles = new Tile[Width * Height]; } public TileWrapper(int width, int height) { Width = width; Height = height; tiles = new Tile[Width * Height]; } /// <summary> /// Accessor for tiles /// </summary> /// <param name="x">X Position</param> /// <param name="y">Y Position</param> /// <param name="overide">Bool to "override" the get, if true, it wont get the reference tile and will bypass the checks</param> public Tile this[int x, int y, bool override = false] { get { //If we do not want to bypass the checks, AND the current tile is > than 1x1 if (!override && tiles[y * Width + x].IsLarge) return tiles[tiles[y * Width + x].refY * Width + tiles[y * Width + x].refX]; //Use the reference positions to get the main position of the tile //If we want to bypass the checks or the tile wasn't large, get the absolute position else return tiles[y * Width + x]; } set { //Same thing for SET if (!override && tiles[y * Width + x].IsLarge) //Set base tile if the large tile has a reference tiles[tiles[y * Width + x].refY * Width + tiles[y * Width + x].refX] = value; else //Set absolute tile tiles[y * Width + x] = value; } } </code></pre> <p>Sorry if it is a bit hard to read with the 2D to 1D conversion, but after doing some testing it looks like using a 1D array internally is a bit faster.</p> <p><code>IsLarge</code> is a property that simply checks if a tile, well, is large (greater than 1x1)</p> <p>I already have logic in place to fill the adjacent tile's references when a large tile is placed, and to remove them accordingly.</p> <p>While profiling the game I found that the get accessor for the tile was eating up a lot of CPU, getting tiles hundreds of times per frame for lighting, rendering, collision, etc. </p> <p>How can I improve the performance and efficiency of this code?</p> <p><strong>Benchmarks</strong> (Average of 30k iterations on an Intel Quad Core i7 2670QM)</p> <p><code>Tile t = tiles[100, 100];</code> - 160 ns and 175 ns WITH 2D Internal Array</p> <p><code>Tile t = tiles[100, 100, true];</code> - 137 ns and 264 ns WITH 2D Internal Array (odd)</p> <p><code>100,100</code> is not a large tile by the way, note that these tiles are not very common. I you had a house on screen, you could have a few large tiles (doors, tables), but lots of dirt/stone/wood.</p>

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