[JAVA][Beginning Java 8 Games Development]

Chapter 16 ■ Collision Detection: Creating SVG Polygons for the Game Actors and Writing Code to Detect Collision
You may have noticed that there are three identical X,Y data point coordinate values for every point, except
for the starting and ending point, for which we have data point pairs instead of data point triplets. If you recall
back in Table 16-1, the only SVG command that uses triplet (three) X,Y data point pairs is the C, or Cubic Bezier
(Spline) Curve. Sure enough, as you see in Figure 16-15, right under the M (moveto) opening SVG command is the
C command. This explains why GIMP put three data points in each point in your polygon. The reason all the data
point triplets have the same value is because we checked the polygon option in GIMP. This puts the spline curve
control handles “away” or out of sight, directly on top of the X,Y data point. This defines zero curvature, or the square
polygon structure seen in Figure 16-14.
Let’s export the SVG data with the triplets removed, which is shown in Figure 16-15, and see what the result looks
like in GIMP, using our newfound Import Path work process, primarily for learning purposes, as we are not quite
finished with the optimization work process.
Figure 16-15. Remove duplicate point data for those points in the interior of the collision polygon, to further optimize
Save the XML data shown in Figure 16-15 as sprite1svghandintegerxmloptimized.txt and then use the same
Import Path work process, shown in Figures 16-12 and 6-13, to import this further optimized SVG data set into GIMP.
As you can see in Figure 16-16, removing those cubic Bezier curve control handles from the data set also removes the
polygonal nature of your collision polygon. So, we will need to do some further work on our SVG data to correct this.
www.it-ebooks.info
359