\u201cAn underlying theme I have discovered with Flash is that you are often better off writing your own code than trusting Adobe\u2019s classes and functions, data structures are no exception.\u201d \u2013 taken from my flash particle system article<\/a> <\/p>\n After the launch and first few patches of Lego Universe<\/a>, work at NetDevil<\/a> has calmed down enough that I have the time and energy to explore private projects again. The current project I am working on is large and it is still in the design, test, research phase since it needs to very optimized. I saw that I was going to be doing quite a few rectangle intersects and intersection operations (the function that determines whether two rectangles overlap and the function that returns the overlapping rectangle respectively) so I took a look at the speed of Flash\u2019s native rectangle class<\/a>. I clocked Flash\u2019s intersects function speed at over 150 simple operations (adds, multiplies, and accessing class members all count as one simple operation from my benchmarking series<\/a>). I thought to myself \u201cI can do better than that\u201d \u2013 I was right, and I managed to write a faster intersection function too (free code).<\/p>\n <\/p>\n These speed tests are just from my minimum spec machine \u201cComputer A\u201d (Gateway Desktop, Intel Pentium 4 chip, 2.27 GHz, 1 GB RAM, Windows XP SP3). I am sure that there will be a little variance across different machines, but since my intersects function was over 4 times faster than Adobe\u2019s, I am pretty confident that it will be faster for every machine out there. Relative speed listed here is in comparison to the cost of a simple operation.<\/p>\n Comparing Adobe\u2019s rectangle functions to mine, 1,000,000 executions per trial. Run the benchmarks: Flash\u2019s native rectangle class<\/a>, My ActionScript 3.0 rectangle class<\/a><\/p>\n
| <\/th>\n | Flash\u2019s functions<\/th>\n | Relative Speed<\/th>\n | Average<\/th>\n | Std. Dev.<\/th>\n<\/tr>\n | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Computer A<\/td>\n | intersects (overlap)<\/td>\n | 162.5<\/td>\n | 0.6513<\/td>\n | 0.0246<\/td>\n<\/tr>\n | |||||||||||||||||
| intersects (containment)<\/td>\n | 157<\/td>\n | 0.6269<\/td>\n | 0.0515<\/td>\n<\/tr>\n | ||||||||||||||||||
| intersection<\/td>\n | 174<\/td>\n | 0.6962<\/td>\n | 0.0124<\/td>\n<\/tr>\n<\/colgroup>\n<\/tbody>\n<\/table>\n Flash\u2019s native rectangle intersects function is so slow, and so close to the speed of actually calculating the intersection, there is no point to ever use it. You might as well just ask for the intersection and check to see it if it is null. There is no reason for an intersection test to be running that slowly, here are the results of my implementation:<\/p>\n
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