I need to perform distance calculations between a number of fixed 'hotspots' and a draggable movie clip on a 2d plane.
To reduce the number of calcualtions I only want to be concerned with those 'hotspots' that are 'closest to' the movieclip at any given time. So I need to perform some sort of 'proximity test' In an earlier post someone pointed out Grant Skinner's Proximity class, which is useful if all of your hot spots are moving. Martin Wood alos opnend my eys to something called 'quadtrees' which is a method of spatial partitioning absolutely essential in reducing the number of calculations in games involving a lot of 3d rendering and spatial movement. A great reference here: http://www.gamedev.net/reference/articles/article1303.asp The simple quadtree I have in mind would be composed of a 16X16 grid of cells or 'leaves'. The dimensions of our draggable clip would also be smaller than each cell. To simplify things each 'base node' I would define as having 2X2 or 4 cells. So there would be a total of 256 cells and 64 'base nodes'. The total number of nodes in this scenario would be: 4 (1st level nodes) + 4X4 (2nd level nodes) + 4X(4X4) (3rd level or 'base nodes') = 84 total nodes So, to begin, I create this grid, then create my nodes array (or arrays). Each node in the array would be composed of x,y,width,height (probably simpler to do the width, height calculation up front than simply using bounding points) At any given time there would be four 'base nodes' that would be considered 'nearest neighbours'......we need to check for and return the current plus 3 additional 'base nodes' depending on which one of four cells in the current 'base node' we're 'over' at any given time (this is easier to ilustrate on a sheet of graph paper). But the net result is that we are dealing with only 4 as opposed to 64(the entire grid) 'base nodes' or 16 vs 256 cells...a savings or reduction of 16X. So i guess what I'm asking is What is the best way to set up the node array(s)? (nested , associative, using objects, etc) and Given the current x,y coordinates of the draggable movieclip and the nodes array(s), how to perform the quadtrees calculaton? Thanks Jim Bachalo [e] jbach at bitstream.ca [c] 416.668.0034 [w] www.bitstream.ca -------------------------------------------- "...all improvisation is life in search of a style." - Bruce Mau,'LifeStyle' _______________________________________________ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
