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World.cpp
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World.cpp
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#include "AbstractObject.h"
#include "World.h"
#include <cassert>
World::World(float aWidth, float aHeight)
: theWidth(aWidth), theHeight(aHeight), theWorldPtr(this)
{
}
World::~World()
{
theWorldPtr = nullptr;
}
void World::addObject(AbstractObject *anAOPtr) {
assert(std::end(theAOList) == std::find(std::begin(theAOList), std::end(theAOList), anAOPtr));
anAOPtr->theWorldPtr = this;
theAOList.push_back(anAOPtr);
}
bool World::wouldBeColliding(const AbstractObject *anAOPtr, const Position& aPos, float aw, float ah) const
{
// We're going to implement the Axis-Aligned Bounding Box (AABB) collision strategy for now:
// https://developer.mozilla.org/en-US/docs/Games/Techniques/2D_collision_detection .
// That formula works with top-left corners, widths and heights.
// Disadvantage: doesn't take non-rectangular shapes into account.
// Using an AABB is an approximation at best anyway.
assert(nullptr != anAOPtr);
assert(std::end(theAOList) != std::find(std::begin(theAOList), std::end(theAOList), anAOPtr));
qreal ax = aPos.x - aw/2.;
qreal ay = aPos.y - ah/2.;
// find the first colliding one
for(auto& i : theAOList) {
if (i != anAOPtr) {
qreal ih = fabs(i->theHeight * cos(i->theCenter.angle)) + fabs(i->theWidth * sin (i->theCenter.angle));
qreal iw = fabs(i->theHeight * sin(i->theCenter.angle)) + fabs(i->theWidth * cos (i->theCenter.angle));
qreal ix = i->theCenter.x - iw/2.;
qreal iy = i->theCenter.y - ih/2.;
// thanks to the above short hand, this looks like the formula from the above link
if ( ix < ax+aw &&
ix+iw > ax &&
iy < ay+ah &&
iy+ih > ay) {
return true;
}
}
}
return false;
}