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Author Topic: Vector2 - type safety between Point and Vector (dimension)  (Read 331 times)

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Vector2 - type safety between Point and Vector (dimension)
« on: March 10, 2024, 09:31:46 am »
I have recently used Vector2 for several functions, in some cases as Point and in some cases as Vector (dimension).
I have found that it is not the best especially if function parameters need both, point/s and vector/s.
I have created class Line which just has two points and an enum for line type (straight, ray, segment).
It was much better and safe however, it needs to create a line and sometimes you have just a point and vector or two points.

So another step is to split general sf::Vector2 into two types:
- Point2
- Vec2
And define operations over them. I found it as really big advantage as it can forbid meaningless operations.
Point2f pointA {1.f,1.f};
Point2f pointB {2.f,2.f};
Vec2f vecA {3.f, 0.f};

auto bLessA = pointB - pointA; // bLessA is Vec2f because operand- for two points are not defined
auto pointC = bLessA + vecA; // Error as there is no overloaded operand+ for two points
auto aAddVecA = pointA + vecA; // type is Point2f

This allows me to define function parameters much more safely (used C++20):

template <typename T>
concept arithmetic = std::integral<T> || std::floating_point<T>; // more strict definition to general definition

template <arithmetic T>
auto linesIntersection (const Point<T>& pointA, const Vec<T>& vecA, const Point<T> pointP, const Vec<T>& vecP)
-> std::optional<Point<T>>;

template <arithmetic T>
auto linesIntersection (const Point<T>& pointA, const Point<T>& pointB, const Point<T>& pointP, const Point<T>& pointQ)
-> std::optional<Point<T>>;

Would not be useful that type safety even for SFML?


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Re: Vector2 - type safety between Point and Vector (dimension)
« Reply #1 on: March 11, 2024, 08:43:29 am »
In a strict sense, math doesn't know the difference between a point and a vector.
A "point" in your definition is just a vector from the origin (0, 0).

I personally don't see the advantage of differentiating between the two, beyond having a "simpler" mental modal at times.
I'd even claim that with more advanced math scenarios, the difference will actually get in the way and you'd have to either use vectors for everything or keep converting between the two a lot.
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