Dorling Kindersley's Screen Shot books incorporate a novel, but effective method of teaching programming on the Commodore 64. Each book is actually illustrated with screen shots, not only of the program listings, but of their results. The first two books in the series - on Basic programming - were a little disappointing, but books three and four warrant a better reception.
Both are concerned with the C64's graphics capabilities in slightly different ways. Book three deals with high resolution displays, whereas book four is concerned solely with the design and programming of sprites.
Book Three contains a number of machine-code programs which add powerful hi-res graphics commands to the C64's Basic. The machine code programs are entered in the form of a simple Basic loader program which POKEs the code into memory from data statements. So you don't have to know any machine language and indeed no attempt is made to explain the inner workings of the routines. Instead they are incorporated in Basic programs where a full explanation is given of what's going on.
Having entered the routine which plots a single pixel at any specified point on the hi-res screen you can include it in a program which draws realistic looking planets. Interesting patterns and landscapes can be created using the line drawing function.
The subjects become more ambitious as you progress, including circles and arcs, shape filling, pattern filling, and user defined graphics. The book also contains a number of useful utilities like a character designer and graphics editor.
Book four - on sprites - takes a different approach. First of all, simple sprite programming is covered with the help of a few Basic programs. Here you will learn how sprites are made up and controlled, how to code them manually and store the data in memory, how to switch them on and off, move them around, colour them, etc. You are also shown how to include sprites in games, with a few examples thrown in.
The next section of the book is basically a listing for a fairly good sprite editor which enables you to design and store up to 32 sprites in memory at any one time. Much less tedious than the felt tip and back of an envelope method! This editor has all the usual features including the most useful of all; a facility to turn your sprites into data statements for inclusion in your own programs.
Knowing how to program sprites is only half the story though. Probably the most difficult aspect is designing them. The second half of the book is a directory of over two hundred sprite designs. So if you're stuck for a space crab, lost for a lunar lander, or like me, simply bereft of any artistic talent whatsoever, this is the place to look.
Both these books are highly recommended to anyone considering adding graphics skills to their programming repertoire whether beginner or experienced. The 'Screen Shot' format makes for easy comprehension as well as ensuring mistake-proof program entry.
1st November 1985
