testsAndMisc/SFMLEngine/makingAGameTick/Classes/SceneNodeDerrivatives/SceneNode.cpp

87 lines
2.8 KiB
C++

#ifndef SCENE_NODE_CPP
#define SCENE_NODE_CPP
void SceneNode::attachChild(ScenePointer child) // takes ownership of the scene node
{
child -> mParent = this;
mChildren.push_back(std::move(child));
}
SceneNode::ScenePointer SceneNode::detachChild(const SceneNode& node) // finds node, releases it and returns it to caller
{
auto found = std::find_if
(
mChildren.begin(), mChildren.end(),
[&] (ScenePointer& p) -> bool { return p.get() == &node; }
);
// This is lambda expression
// [&] (ScenePointer& p) -> bool { return p.get() == &node; }
// [&] - how many and in what way will the lambda expression have access to the variables in surrounding scope, [] - no variables [&] - all variables by reference [=] - all variables by value
// (ScenePointer& p) - parameters passed to the function
// -> bool - return type
// function body encolsed in {}
assert(found != mChildren.end()); // We check validity of the iterator of the found element
ScenePointer result = std::move(*found); // we move the found node out of the container to result
result -> mParent = nullptr; // node's parent is set to null pointer
mChildren.erase(found); // we erase this element from the container
return result; // and we return the pointer to the node
}
void SceneNode::drawCurrent(sf::RenderTarget& target, sf::RenderStates states) const
{
}
void SceneNode::draw(sf::RenderTarget& target, sf::RenderStates states) const
{
states.transform *= getTransform();
// *= combines the parent's absolute transform with the relative one of the current node;
// states.transform contains the absolute world transform
drawCurrent(target, states); // now we can draw the derived object using states, this is similar to how sf::Sprite handles transforms
for (const ScenePointer& child : mChildren)
{
child -> draw(target, states); // we also need to draw all the child nodes
}
}
void SceneNode::updateCurrent(sf::Time deltaTime)
{
}
void SceneNode::updateChildren(sf::Time deltaTime)
{
for (const ScenePointer& child : mChildren)
{
child -> update(deltaTime); // we also need to draw all the child nodes
}
}
void SceneNode::update(sf::Time deltaTime)
{
updateCurrent(deltaTime);
updateChildren(deltaTime);
}
sf::Transform SceneNode::getWorldTransform() const
{
sf::Transform transform = sf::Transform::Identity; // sf::Transform::Identity represents the identity transform - it does not have any effecft on the object, it is not necessary in the code but it clarifies how transforms are applied
for (const SceneNode* node = this; node != nullptr; node = node -> mParent)
{
transform = node -> getTransform() * transform;
}
return transform;
}
sf::Vector2f SceneNode::getWorldPosition() const
{
return getWorldTransform() * sf::Vector2f();
}
#endif