Checking for collisions in a single list
BlitzMax Forums/BlitzMax Programming/Checking for collisions in a single list
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| I have a single list in a tentity type that all of my other game types are extended from, for example player, enemies, bullets and so on. All seems to work well, I can update all of my game objects by running through this single list that everything gets added to when it is created. The problems begin when I try to check for a collision between two of the object in the one, single list. How can I check for example for collisions between the players bullets and the enemies to see if they have been hit? Is there a way to find out whether a type is an enemy or a player and so on? I`m a little confused but I`m sure that the solution is really simple. Do I need to use multiple lists instead? One for the enemies, one for the bullets... I`d really like to stick to the one if possible. Any examples or help would be most appreciated. Jason. |
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its as simple as:for e:enemy=eachin entitylist for b:bullet=eachin entitylist collisions next next |
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| Ouch... isn't that going to be painfully slow? I posted an example the other day, where you can hide away the fact that you are using multiple lists. Smaller lists would mean more efficiency, in theory. |
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| What if you were to put all the bullets on one layer, enemies on another and the player on a third? |
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| Yes, check out the layering capability of the BMax collision checking functions: It's a little weird at first, but it is more efficient because you can group items by how they are supposed to interact: Bullets shouldn't collide with other bullets, for example. Or, check the type of the object before collision checking (if the current object is a bullet, skip over other bullets objects, etc). Russell |
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| Smaller lists would mean more efficiency, in theory. Yeah, in theory... In practice there may also be negative effects on performance (eg. cache misses) from multiple lists. Unless there's a great need of performance, using a single list is good enough. And for something that performance critical, TList is way too slow. |
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| Thanks for the help. So is there a way to check the type of an object just out of interest? Jason. |
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For Local obj:Object = EachIn MyList If TPlayer(obj) Local player:TPlayer = TPlayer(obj) 'etc.. Else If TBullet(obj) Local bullet:TBullet = TBullet(obj) 'etc.. End If Next Something of that sorte. |
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| Thanks, I`ll give it a go. Jason. |
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| Use callbacks for collisions, it is a much better solution. |
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| Use callbacks for collisions, it is a much better solution. Only in 3D. |
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| I've tried to find some more information specific on callbacks for collisions and i found a lot of threads pointing toward a document on a guys website that no longer exist. Could you point me in the right direction for some more information about this? Because i don't know exactly what to look for i just get too much hits in google where the words just exists but there's nothing specific on collision callbacks. I know, i should find it myself but it would really help if you could point me in the right direction. I read this but i just don't understand it :( Oh wait, just in 3D? I only want to make 2D games. What would be the 'best' solution for 2D in your opinion? Sigh, i should stay in the beginners corner. |
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| I don't use bmax pixel collision routines, but for circle, dist, rect, etc, I just iterate each bullet through a list of sprites (as JP said) and it works fine. Even with hundreds (or 1000's) of objects on screen. |
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| "iterate each bullet through a list of sprites" I'm sorry but i don't understand what that means. I have my big list with all my gameobjects, i cycle thrue them and then... ? |
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