Notes.txt

// collision programming involves 2 stages
// collision detection
// collision resolution

// point inside AABB
// px > x1 && px < x2
// py > y1 && py < y2

// AABB intersection
// two AABB intersect if they overlap both horizontally and vertically

// AABB Horizontal Overlap
// - occurs if the top of each box is higher than the bottom of the other
// y1 < y2 + h2
// y2 < y1 + h1

// AABB Vertical Overlap
// - occurs if the left of each box is less than the right of the other
// x1 < x2 + w2
// x2 < x1 + w1

// Our game engine uses the CENTER of the entity as the position for the AABB
class CTransform: public Component
{
    Vec2 pos = { 0.0, 0.0 };
    Vec2 prevPos = { 0.0, 0.0 };
    Vec2 scale = { 1.0, 1.0 };
    Vec2 speed = { 0.0, 0.0 };
    float angle = 0;
};

class CboundingBox : public Component
{
public:
    Vec2 size;
    Vec2 halfSize;
    CBoundingBox(const Vec2 & s) : size(s), halfSize(s.x/2, s.y/2) {}
};

dx = abs(x2 - x1);
// overlap in x-direction:
ox = (w2 / 2) + (w1 / 2) - dx // positive if x overlap
dy = abs(y2 -y2)
// overlap in y-direction
oy = (h2 / 2) + (h1 / 2) - dy // positive if y overlap
overlap = [ox, oy]