//=============================================================================
// Rotated Box collision detection method
// Called by collision()
// Post: returns true if collision, false otherwise
// sets collisionVector if collision
// Uses Separating Axis Test to detect collision.
// The separating axis test:
// Two boxes are not colliding if their projections onto a line do not overlap.
//=============================================================================
bool Entity::collideRotatedBox(Entity &ent, VECTOR2 &collisionVector)
{
computeRotatedBox(); // prepare rotated box
ent.computeRotatedBox(); // prepare rotated box
if (projectionsOverlap(ent, collisionVector) && ent.projectionsOverlap(*this, collisionVector))
return true;
return false;
}
//=============================================================================
// Rotated Box collision detection method
// Called by collision()
// Uses Separating Axis Test to detect collision.
// The separating axis test:
// Two boxes are not colliding if their projections onto a line do not overlap.
// The current entity is A the other entity is B
// Post: returns true if collision, false otherwise
// sets collisionVector if collision
//=============================================================================
bool Entity::collideRotatedBox(Entity &entB, VECTOR2 &collisionVector)
{
float overlap01, overlap03;
computeRotatedBox(); // prepare rotated box
entB.computeRotatedBox(); // prepare rotated box
if (projectionsOverlap(entB, collisionVector) && entB.projectionsOverlap(*this, collisionVector))
{
// If we get to here the entities are colliding. The edge with the
// smallest overlapping section is the edge where the collision is
// occuring. The collision vector is created perpendicular to the
// collision edge. The projection edges are 01 and 03.
//
// entA01min
// / entB01min
// / / entA01max
// / / / entB01max
// / / / /
// 0--------------------1
// entB03min..| ____
// entA03min..| _____|_ B |
// | | A | | |
// entA03max..| |_____|_| |
// entB03max..| |____|
// |
// |
// 3
//
if (entA01min < entB01min) // if A left of B
{
overlap01 = entA01max - entB01min;
collisionVector = corners[1] - corners[0];
}
else // else, A right of B
{
overlap01 = entB01max - entA01min;
collisionVector = corners[0] - corners[1];
}
if (entA03min < entB03min) // if A above B
{
overlap03 = entA03max - entB03min;
if (overlap03 < overlap01)
collisionVector = corners[3] - corners[0];
}
else // else, A below B
{
overlap03 = entB03max - entA03min;
if (overlap03 < overlap01)
collisionVector = corners[0] - corners[3];
}
return true;
}
return false;
}
//=============================================================================
// Rotated Box collision detection method
// Called by collision()
// Post: returns true if collision, false otherwise
// sets collisionVector if collision
// Uses Separating Axis Test to detect collision.
// The separating axis test:
// Two boxes are not colliding if their projections onto a line do not overlap.
//=============================================================================
bool Entity::collideRotatedBox(Entity &ent, VECTOR2 &collisionVector)
{
computeRotatedBox(); // prepare rotated box
ent.computeRotatedBox(); // prepare rotated box
if (projectionsOverlap(ent) && ent.projectionsOverlap(*this))
{
// set collision vector
collisionVector = *ent.getCenter() - *getCenter();
return true;
}
return false;
}
