What's New -  September 2002

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September 28, 2002:

 I ran across this experiment the other day which uses playing cards to start us thinking about  the Number of Divisors of positive integers.    This simple little program uses card images and flips them for you in case you have mislaid your real deck. 

September 21, 2002:  Here's another program, Pendulums Simple and Otherwise, written to exercise the Runge-Kutta  differential equation solver posted a couple of weeks ago.  This version explores three pendulum variations - Simple, Double, and Damped Forced.   Interesting to play with, even if you're not into that higher math stuff.    

September 16, 2002:   Occasionally it's convenient to identify which version of Delphi is being used to compile a program.  Borland  predefines conditional symbols identifying Delphi versions but the values are not very well documented.  I just spent a couple of hours tracking them down so here's a  Testing  Delphi Versions  page to save doing it again.

September 11, 2002:   While working on the Sprite Animation program, I had to study up on Mask drawing, the tricky way that programs can nicely put a non-rectangular image over another image using a system that only knows how to draw rectangles (i.e. Windows).    

Here's a Mask Drawing description and demo program revealing how the trick is performed.

September 8, 2002:  I finished  working on some Sprite Animation demo programs this week and posted them over in the Delphi Techniques section.    Really just an investigation to the mysteries of making non-rectangular things (ellipses and letters and a little walking man) move smoothly and quickly across the screen.    Some of the mysteries are even solved!