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Asked: 2026-05-10T23:19:00+00:00

I’m writing a little arcade-like game in C++ (a multidirectional 2d space shooter) and

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I’m writing a little arcade-like game in C++ (a multidirectional 2d space shooter) and I’m finishing up the collision detection part.

Here’s how I organized it (I just made it up so it might be a shitty system):

Every ship is composed of circular components – the amount of components in each ship is sort of arbitrary (more components, more CPU cycles). I have a maxComponent distance which I calculate upon creation of the ship which is basically the longest line I can draw from the center of the ship to the edge of the furthest component. I keep track of stuff onscreen and use this maxComponentDistance to see if they’re even close enough to be colliding.

If they are in close proximity I start checking to see if the components of different ships intersect. Here is where my efficiency question comes in.

I have a (x,y) locations of the component relative to the ship’s center, but it doesn’t account for how the ship is currently rotated. I keep them relative because I don’t want to have to recalculate components every single time the ship moves. So I have a little formula for the rotation calculation and I return a 2d-vector corresponding to rotation-considerate position relative to the ships center.

The collision detection is in the GameEngine and it uses the 2d-vector. My question is about the return types. Should I just create and return a 2d-vector object everytime that function is called or should I give that component object an additional private 2d-vector variable, edit the private variable when the function is called, and return a pointer to that object?

I’m not sure about the efficiency of memory allocation vs having a permanent, editable, private variable. I know that memory would also have to be allocated for the private variable, but not every time it was checked for collisions, only when a new component was created. Components are not constant in my environment as they are deleted when the ship is destroyed.

That’s my main dilemma. I would also appreciate any pointers with the design of my actual collision detection system. It’s my first time giving a hack at it (maybe should have read up a bit)

Thanks in advance.

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  1. You should absolutely try to avoid doing memory allocations for your component-vector on each call to the getter-function. Do the allocation as seldom as possible, instead. For instance, you could do it when the component composition of the ship changes, or even more seldom (by over-allocating).

    You could of course also investigate memory pools, where you pre-allocate lots of such components and put in a pool, so you can allocate a new component in constant time.

    As a general (and apologies if it’s too obvious) point when doing this kind of collision-detection: square the distances, rather than computing the square roots. 🙂

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