Collision Detection and EverFire Studios!

Busy, busy, busy are my three excuses. It is still within the month and I will still try to update as much as possible in regards to my game engine, but man, I must go on a rant.

So, as mentioned before, I have started a job at EverFire Studios in Milwaukee, WI as a game play programmer. Currently, we are working on developing a new game and it has taken a lot of my attention. Perhaps when it goes alpha I will show some game play videos. On top of school and a second job, I have not had much time to work on my engine.

Well, at least I have something to show you. It is exciting and incredible...
It is two boxes detecting a collision with each other, and don't worry my spheres can do it too. With this I will implement a Rigid body physics system. But, honestly, I don't like programming physics - so I may go back to my renderer and implement a shader for diffuse, normal, and specular mapping as that is the bare minimum I want on my models in the engine.

Speaking of which, I need to think of a name... still!

So, since I wish to have this be somewhat intellegent, the idea behind simple AABB (Axis Aligned Bounding Box) and Sphere Collision is all of but a few simple statements. In order to get the code from this we just need to do the following:

Two spheres collide it the distance between their center points is less than their combined radii.
Two AABB collide when the absolute values of the x, y, and z coordinates of the length vector between the center points of each AABB is less than the cumulative values of the respective coordinate extents.

The sphere was easy, the AABB tests were a mouthfull, so here is the code in its simplest iteration:

bool Intersect(const AABBCollider& pVolume, const AABBCollider& other)
{
XMVECTOR volumeCenter = XMLoadFloat3(&pVolume.getCenter());
XMVECTOR otherCenter = XMLoadFloat3(&other.getCenter());

FXMVECTOR length = otherCenter - volumeCenter;

return fabs(XMVectorGetX(length)) <= (pVolume.getExtents().x + other.getExtents().x) &&
fabs(XMVectorGetY(length)) <= (pVolume.getExtents().y + other.getExtents().y) &&
fabs(XMVectorGetZ(length)) <= (pVolume.getExtents().z + other.getExtents().z);
}

And yes, for right now I am using xnamath for my math library; perhaps that will change too.

Until next time, enjoy game programming!