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POPixel level collision detection fails for small objects. (Java)
 

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  1. POPixel level collision detection fails for small objects. (Java)
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    <p>For a project we were given a game engine off which to create a game. We, as part of this, have to implement pixel level collision detection after a possible collision has been found via a bounding box detection method. I have implemented both but my pixel level test fails for small objects (bullets in this case). I have checked if it works for slow bullets but that fails too. </p> <p>For my pixel level implementation I create bitmasks for each texture using an the available IntBuffer (a ByteBuffer is available too?). The IntBuffer is in RGBA format and its size is width*height, I placed this in a 2D array and replaced all non-zero numbers with 1's to create the mask. After a collision of bounding boxes I find the rectangle represented by the overlap (using .createIntersection) and then check the maps of both sprites within this intersection for a nonzero pixel from both using bitwise AND.</p> <p>Here is my code for the pixel level test:</p> <pre><code>/** * Pixel level test * * @param rect the rectangle representing the intersection of the bounding * boxes * @param index1 the index at which the first objects texture is stored * @param index the index at which the second objects texture is stored */ public static boolean isBitCollision(Rectangle2D rect, int index1, int index2) { int height = (int) rect.getHeight(); int width = (int) rect.getWidth(); long mask1 = 0; long mask2 = 0; for (int i = 0; i &lt; width; i++) { for (int j = 0; j &lt; height; j++) { mask1 = mask1 + bitmaskArr[index1].bitmask[i][j];//add up the current column of "pixels" mask2 = mask2 + bitmaskArr[index2].bitmask[i][j]; if (((mask1) &amp; (mask2)) != 0)//bitwise and, if both are nonzero there is a collsion { return true; } mask1 = 0; mask2 = 0; } } return false; } </code></pre> <p>I've been struggling with this for days and any help will be greatly appreciated. </p>
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    1. COfrom `file:///C:/Documents%20and%20Settings/ser/Desktop/java3d/Shoelace%20formula%20-%20Wikipedia,%20the%20free%20encyclopedia.htm` you can find area of one of the shapes........ If area of union-of-them is smaller than sum of areas of distinct shapes, then they are colliding. This is O(n+m) way better than O(n*n)
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      1. UShuseyin tugrul buyukisik
    2. COThanks for the advice but I have to implement this sort of testing.
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