Introduce GameObjects and Components. #3
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| /// A component by itself has no meaning, and is useful to describe properties or attributes | ||
| /// of a `wex::GameObject`. | ||
| /// Extend this class to use custom components. | ||
| struct Component { |
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Convention is to have such things be classes, structs don't usually have virtual semantics.
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My reasoning was this is more of a C-style "bag of data", rather than mutable state + mutating functions. So I went with a struct here. is that okay?
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Sure, just letting you know what to expect elsewhere
| T* give(Args&&... args) { | ||
| auto compPtr = std::make_unique<T>(std::forward<Args>(args)...); | ||
| mComponents.push_back(std::move(compPtr)); | ||
| return reinterpret_cast<T*>(mComponents.back().get()); |
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static_cast pls! reinterpret will cast anything without care, we mostly restrict it to primitives only.
include/wex/presets/GameObject.hpp
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| virtual void onUpdate([[maybe_unused]] double dt) {} | ||
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| template <typename T> | ||
| T* get() { |
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Should be a const member function (don't need non const overload, because pointer isn't const)
include/wex/presets/GameObject.hpp
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| /// TODO: optimize this O(n) lookup | ||
| for (auto const& compPtr : mComponents) { | ||
| auto comp = dynamic_cast<T*>(compPtr.get()); | ||
| if (comp != nullptr) return reinterpret_cast<T*>(comp); |
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Pls no reinterpret_cast 😭
Here you can just return comp
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lol, alright. Why is reinterpret_case bad?
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It's basically (foo)bar: there are no checks whatsoever, and unlike in C, materializing an object (or a pointer to one) that was never created before is UB in C++.
src/main.cpp
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| template <typename T> | ||
| struct Shape : wex::Component { | ||
| T shape; | ||
| Shape(T&& shape_) : shape(shape_) { |
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rvalue that's not moved? sus...
| void onUpdate(double) override { | ||
| sf::Vector2f const& vel = this->get<wex::CVelocity>()->vel; | ||
| auto& shape = this->get<CCircleShape>()->shape; | ||
| shape.setPosition(shape.getPosition() + vel); | ||
| } |
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Missing * dt for framerate independence.
src/main.cpp
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| } | ||
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| void draw() override { | ||
| g->draw(mCircle); | ||
| g->draw(ball.get<CCircleShape>()->shape); |
A
GameObjectis a wrapper around astd::vectorof Components, along with anonUpdatemethod.Current app is a circle that slowly moves from the topleft to the bottom right of the screen.
Eventually this will become the ball in
pong.Files added:
include/wex/presets/GameObject.hppinclude/wex/presets/Component.hpp