Game Development Reference
In-Depth Information
Figure 13-1 . The pinball table built in this chapter
Shapes: Convex and Counterclockwise
Let's start with the requirements of collision polygons. The first thing you need to be
aware of when defining collision polygons for Box2D and Chipmunk is that these en-
gines expect the collision polygons to have the following properties:
▪ Vertices defined in a counterclockwise fashion
▪ Polygons as convex shapes
A convex shape is a shape where you can draw a straight line between any two points
without the line ever leaving the shape. In concave shapes, you can draw a straight line
between two points such that the line is not entirely contained within the shape. Figure
13-2 illustrates the difference between convex and concave shapes.
 
 
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