This page last updated
27 December 1997

Waiheke Paul's Line Animated Checkerboard Painter

If this spot is not green you may want to download the latest Tcl Plugin.
This is one of the most complex of the painters, as can be seen from the controls. It is basically the checkerboard painter, extended to allow for animation. Only one type of animation is implemented at present. I will implement others as time allows. You should be familiar with the checkerboard painter before attempting to use this painter. The additional controls are the "frame animation button" and the "formula box".

The formula entry works the same way as the formula entry in the label painter, except it operates at the frame level. Basically it indicates an "on"(Frame 1) and an "off"(Frame 0) for each frame. The parameter "x" goes across the screen from left to right starting at "0". The "y" parameter goes down the screen starting again at "0". The painter inserts sufficient code to ensure that the "formula" evaluates to "0" or "1", namely it takes the 2-modulus of the integer part of the formula. If the formula you write does not seem to be taking effect it may be because Tcl detects an error in the formula syntax. A large Tcl error window should appear with a line containing your formula highlighted in blue. Just Dismiss the frame, at the bottom right corner, correct or rephrase the formula and try again.

The frame animation switch causes the grid of frames to move from right to left. As the animation continues the "x" value increases conceptually in order to evaluate the next column on the right end. It does not just recycle what you can already see.

Any adjustment to the frame variables will cause the animation to stop. Simply restart the animation when your adjustments are complete. The animation will take a few cycles to reestablish itself. This will not happen to the animation produced by the generated code.

At present there is no speed adjustment. The more frames in your pattern, the slower the animation is, and the more load is placed on your clients system resources. The load could be sufficient to make web browsing unacceptably slow, so please be careful and considerate in this regard.

The generated code is stored in your Tclet Temp file "checkpaint.txt" which is the same name (and same file) as the checkerboard painter file. NOTE Care should be taken when setting the widths and heights. The first width and height control the size of the whole picture, the tile height and width control the size of the tiles, all of which are the same size. If the tiles are too small your computer can very easily become overloaded.

The generated animation can be turned off and on by clicking on it.

Some useful formulae are:
up to(x+y)%7==0and so on
x-ygives diagonals in the opposite direction

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