So Um Vector Collisions...

[davidthefat]

I understand vectors but I don't understand how one can implement them in programming. Im in Pre Calculus and AP Physics right now, we use vectors all the time in Physics, but still can't get my head around how to use it in programming. I can make a Vector class that has the magnitude and the angle and possibly breaking that up into a X and Y vector using trig, that part is easy. But now when it comes to collision using vectors (it was in one of Falco's "educational" videos) I still don't get how to implement that. Can anyone explain it more in depth? I read some articles online, but still have trouble coming up with anything. I get the concept, but translating that to code is the part I don't get.

Mad props if you can gently push me in the right direction.

[EccentricDuck]

One useful thing you can do with position vectors is calculate the distance between them. This can be used for collision checking or even as a simple conditional statement to rule out a collision (before you get into more expensive code).

Another use of vectors in collisions is for rebounding. You can calculate the angle of deflection when an object hits a wall or surface of another object.

If you deal with matrix transformations then vectors can be used in all kinds of neat ways. While not specifically for collisions, you can use vectors to construct a world matrix (or simply use a library that does it for you if you're not into linear algebra) which opens up a huge number of possibilities for transforming/rotating objects, the "camera", etc.

I use unit vectors to store and calculate where any object is facing, as well as a vector pointing to the right and up from the model. This makes it easy to use a scalar value (like an int or a float) for something like acceleration, and do something like add the value of the acceleration to my velocity vector every frame (so I can get nice smooth turns where I'm accelerating along the curve). To calculate the unit vectors/make sure they stay at right angles to each other, I use cross products so they are all at right angles. I can change them all by other ways, but this keeps them from converging (through rounding errors). I also use unit vectors for constructing my transformation matrix when I go to draw model to the screen.

Vectors are also a useful way of passing position coordinates to a camera system. Basically, you can use them for whatever you want. Vectors are incredibly flexible (without being 2 or 3 separate variables) and you can get creative with them (I think that's probably why vector notation became so popular). Try thinking about what you might be able to use a dot product for (keeping in mind that a dot product corresponds to how much one vector is aligned with another one).

Feel free to ask if you want to hear more. I haven't really told you exactly HOW to do most of those things, but see if that helps and if you're stuck on something then I can give more specific advice. I spent quite a bit of time with some of this stuff since I'd been working on getting a ship to fly around in 3D space with a spring-chase camera system following behind it.