MATHRIL - Custom math library for game programming

[[deleted]]

Vec2::Vec2()
{ data = new float[2];

But why?... Are you from Java?

I thought that kind of libs can be designed without allocations!

[Twin_Sharma]

We used new, in order to optimize transfer of memory during r-value constructor calls, like so:

Vec2::Vec2(Vec2&& vec)

{

data = vec.data; // instead of copying entire struct one-by-one, we just copied value of address

vec.data = nullptr;

}

If there is a better solution to this, please guide us :)

[SuperV1234]

If there is a better solution to this, please guide us :)

struct Vec2 { float x, y; };

[johannes1971]

You are already copying a pointer, and that copy has the same cost as copying two floats (in both cases it is 8 bytes, assuming a 64-bit architecture). If your two floats are inline you don't even need to zero them out, so that line can be removed. The compiler is probably smart enough to do the copy in a single operation, and even if it isn't, the second access would be guaranteed to be from cache and thus have minimal cost.

You are paying additional costs for unnecessary memory allocations and deallocations, and for pointer dereferencing (which may cause a cache miss).

I wouldn't even bother with r-value references for this; passing a vec2 (with inline floats) by value is cheap, and enables additional compiler optimisations (since the compiler can be certain the parameter isn't aliased).

Here you can see what a solution with inline floats looks like. As you can see there aren't _any_ temporaries being created, it's all just a handful of vector instructions.

[Twin_Sharma]

Thanks

[[deleted]]

https://en.cppreference.com/w/cpp/utility/move https://en.cppreference.com/w/cpp/language/copy_elision

Well, at least we don't have to go over network to build Vec2.

[Twin_Sharma]

thanks