Separation of Axis Theorem (SAT) for Collision Detection
The Separation of Axis Theorem(SAT) is a technique to test whether two convex polygons are colliding. The SAT theorem: "given two convex shapes, there exists a line onto which their projections will be separate if and only if they are not intersecting." The line where the shapes have disjoint projections is called the separating axis. A separating line is the line that can be drawn between the two shapes,...
A* Pathfinding Basics
A* (A-star) is an algorithm used for pathfinding. Pathfinding is where a computer computes the shortest (or best) path from a start point to an end point through a grid or nodes. We will be using a grid to find a path. The green cell is the start point and the red cell is the end point. The computer must find the shortest route from start to finish without going through the walls. We are using a grid because...
A* and Pathfollowing Steering Behavior
In the last three posts, we explored the how A* works, then we put A-star into code, then we looked at different heuristics for A*. Now we will combine A* pathfinding with the path following steering behavior. We have already done most of the work to do this. But we'll do a quick review in case you missed those posts. A* Pathfinding In A* we take a grid of cells and find a path from start to finish. Each...
Detecting Collisions with SAT
Today we will finally be detecting a collision with SAT. We know how SAT works, we've built classes to work with SAT, now we can use all of this to detect a real, live collision! Using the classes we created last time, this is quite simple. First create a shape: var shape1:Polygon = Polygon.rectangle(530, 30, new Vector2D(270, 360)); It's a simple polygon created using the static function of the rectangle...
A* Pathfinding Basics
A* (A-star) is an algorithm used for pathfinding. Pathfinding is where a computer computes the shortest (or best) path from a start point to an end point through a grid or nodes. We will be using a grid to find a path. The green cell is the start point and the red cell is the end point. The computer must find the shortest route from start to finish without going through the walls. We are using a grid because...
Steering Behaviors: Flocking
The next post steering behaviors series is unaligned collision avoidance. We will be using the Vector2D.as and Vehicle.as classes for this. You will need these classes for the this post. This post is based on Craig Reynold’s article Steering Behaviors For Autonomous Characters. Flocking is created by combining several steering behaviors: Separation, Cohesion and Alignment. ...
Separation of Axis Theorem (SAT) for Collision Detection
The Separation of Axis Theorem(SAT) is a technique to test whether two convex polygons are colliding. The SAT theorem: "given two convex shapes, there exists a line onto which their projections will be separate if and only if they are not intersecting." The line where the shapes have disjoint projections is called the separating axis. A separating line is the line that can be drawn between the two shapes,...

Archive for July 23, 2010

Steering Behaviors: Unaligned Collision Avoidance

Jul 23rd

This entry is part of 9 in the series Steering Behaviors

The next post steering behaviors series is unaligned collision avoidance. We will be using the Vector2D.as and Vehicle.as classes for this. You will need these classes for the this post. This post is based on Craig Reynold’s article Steering Behaviors For Autonomous Characters.

Unaligned Collision Avoidance, click to watch.

Unaligned Collision Avoidance tries to keep vehicles from colliding with each other. Think of a crowded city. There are a lot of people moving around, but no one runs into someone else. If a person detects a approaching collision, he will steer away from the potential More >

2D, AS3, Math, Steering Behavior, SWF, Vector

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- Using Ray Casting with Shapes February 16, 2011
- Detecting Collisions with SAT November 29, 2010
- Using the Separation of Axis Theorem November 23, 2010
- Steering Behaviors and A* Source November 15, 2010
- A* and Pathfollowing Steering Behavior November 10, 2010

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Archive for July 23, 2010

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