Check if/when/where two objects collide with eachother.
6 Useful Snippets
How to do: Mix (lerp), Golden Ratio Sampling, Exponential Smoothing (easing), Verlet (and Euler) Integration, Spatial Hashing, Iterative Constraint Solving. At the end the author combines these "snippets" into a simple collision detection and response solver.
Point in Polygon Detection Strategies
Testing whether a point is inside a polygon is a basic operation in computer graphics. Graphics Gems presents an algorithm for testing points against convex polygons (Badouel 1990). This Gem provides algorithms which are from 1.6 to 9 or more times faster for convex polygons. It also presents algorithms for testing non-convex polygons and discusses the advantages and drawbacks of each. Faster, more memory intensive algorithms are also presented, along with an O(log n) algorithm for convex polygons. Code is included for the algorithms discussed.