   Bullet Mark
  I`m trying to make a Shoting system(almost done) and i`m having dificulties making the BulletMark(you know : the "hole" it leaves on the ground...)Actually what I need is to make a small quad out of a plane normal/triangle ... So far I have the planes normal and I`m usaing some strafing function to make2 points on the 2 sides and rotate them on 1 axis to make a small quad. The thing is that my code makes different sizes of quads based on the plane/surface wich sucks,what I would like is a simple functions/anything that can make from 1 plane/triangle at a point P a small quad ||(paralel) to the plane .PS:It can also be used to spill blood . 
  I''ve never actually done decals before but this is the way I think you would do it.#1 Decide which face you have hit#2 Get that face''s normal, we can call this vector n#3 Randomly grab two points belonging to the face and create a vector between them. This will be vector v1. Normalize v1.#4 Perform a cross product between v1 and n to get v2. This will give you the second vector you need, which will be perpendicular to the face normal.#5 Scale the vectors v1 and v2 to your desired size of the decal.#5 Create the quad using v1 and v2 