1.3 Game 2302-0110: updating the game math library for graphics  (Page 16/20)

Draw the border

While the single GM2D02.Line object is at each location, draw methods are called to cause a Line2D.Double object to be instantiated and rendered on each of the off-screen images. This results in four differentvisual manifestations of the single GM2D02.Line object, producing visible lines at the edges of each off-screen image. Although this code is notparticularly straightforward, the embedded comments should suffice to explain it.

Draw the hexagon

Essentially the same process is used to draw the hexagon shown in the left image in Figure 1 . You can view the code that does that in Listing 28 . Once you understand the code that I explained above, you should have nodifficulty understanding the code that draws the hexagon.

Draw the vectors

A very similar process is used to draw the vectors shown in the right image in Figure 1 . You can view the code in Listing 28 . Once again, if you understand the code that I explained above, you should have no difficultyunderstanding the code that draws the vectors.

That ends the explanation of the program named PointLine04 .

Documentation for the GM2D02 library

Click here to download a zip file containing standard javadoc documentation for the library named GM2D02 . Extract the contents of the zip file into an empty folder and open the filenamed index.html in your browser to view the documentation.

Although the documentation doesn't provide much in the way of explanatory text (see Listing 26 and the explanations given above) , the documentation does provide a good overview of the organization and structure of the library. You may find ithelpful in that regard.

Homework assignment

Your homework assignment for this module was to study Kjell's CHAPTER 0 -- Points and Lines plus CHAPTER 1 -- Vectors, Points, and Column Matrices down through the topic titled Variables as Elements .

The homework assignment for the next module is to study the Kjell tutorial through Chapter 2 -- Column and Row Matrix Addition .

In addition to studying the Kjell material, you should read at least the next two modules in this collection and bring your questions about that material tothe next classroom session.

Finally, you should have begun studying the physics material at the beginning of the semester and you should continue studying one physics module per weekthereafter. You should also feel free to bring your questions about that material to the classroom for discussion.

Run the programs

I encourage you to copy the code from Listing 26 , Listing 27 , and Listing 28 , compile it, and execute it. Experiment with it, making changes, and observingthe results of your changes. Make certain that you can explain why your changes behave as they do.

Summary

In this module, you learned how to update the game-math library to provide a number of new capabilities including the addition of graphics to the library andthe addition of set methods for column matrices, points, vectors, and lines.

You also saw sample programs that illustrate the use of those new capabilities and you learned how to draw on off-screen images.