So my first program was a color line that moved across screen with a beep as it hit the top. Instant haxxor.
There are two parts of collision detection, the first is to detect if something is not colliding and the second is to detect if something is colliding. Generally speaking the second part is slow and takes many calculations. By finding objects that do not interact as soon as possible in the physics system it need to do less hard work later. They are called broad phase and narrow phase.
The focus of this phase is to get a list of all the objects that have no possibility of colliding in the next simulation update.
This is the no broad phase at all option. Loop all objects and check them against each other and if they collide do something. Works for few objects and if the test is really simple.
for(i=0; i<numObjects-1; i++)
for(j=i+1; i<numObjects; i++)
collideInfo info = collides(obj[i], obj[j])
Split the world into smaller areas based on some rule. Ex are quadtrees, octrees, bsp trees or any sort of tree really. Insert the object into any cells that it's axis aligned bounding box touch. Build a list of object pairs that occupy the same cells as they need to be tested against each other. Next frame rebuild the data.
Sweep and Prune
- GPG 1: p228-238
Here the focus is on is object A colliding with object B and if so how to we get all the information we need about the collision. What happens when the object's that collides does not matter here, thats the response part of the collision.
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Physics for Game Programmers - 2013
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Collision detection for dummies - 2011
Contact Points Using Clipping - 2011
Speculative Contacts – a continuous collision engine approach - 2011
EPA (Expanding Polytope Algorithm) - 2010
GJK – Distance & Closest Points - 2010
GJK (Gilbert–Johnson–Keerthi) - 2010
SAT (Separating Axis Theorem) - 2010
Testing if a point is inside a Polygon - 2010
Sweep and prune - 2007
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Supporting Cylinder Collision - 2007
Robust Continuous Collision Detection - 2005
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General Collision Detection for Games Using Ellipsoids - 2000
Advanced Collision Detection Techniques - 2000
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N tutorial A - Basic Collision Detection and Response
N tutorial B - Grid-Based Collision Detection and Raycasting
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