Dissolve is a program I wrote after reading an article in the Nov 1986
issue of Doctor Dobb's Journal by Mike Morton. It displays a picture in a
random pattern on the screen, which causes the picture to slowly appear as
if dissolving. The affect is rather pleasing. To use the program from the
CLI type the command 'dissolve filename [-speed]'. The file must be a picture
stored in IFF format. All the pictures I have tried work fine, including HAM
pictures. The speed should be a number from 100 to 32565. The speed is optional
with a default value of 1000. Any key press or clicking the mouse pointer in 
the upper left corner will end the display. The right mouse button will hold
the display so that you can slow it down if desired.

Technical Information

	The program has a complete IFF file reader in it which I think is 
pretty nice routine all by itself. It can be used stand alone to display IFF
files. A temporary BitMap is setup for the reader to store the picture in
while it is begining displayed. After the file has been read into the temp
bitmap we start the display routine. This routine has a mask plane which is
used to blit the bitmap with the picture into the bitmap which is used for
the display. Wherever there is a 1 bit in the mask that pixel will be
displayed. Wherever the mask has a 0 bit that pixel will be left blank in the
display. This is where the speed value is used, the speed determines how many
bits to set in the mask before we do each blit to the display.

	The display tends to flicker some during each blit and should probably
be double buffered to make it a little smoother, but it is not to bad. I make
this comment and the ones that follow in the hopes someone will take the time
to make improvements on this program and repost it.

	Many different display effects can be done using this program as a 
start. All you have to do is use a different algorithym to set the bits in
the mask plane and you can create almost any effect you see on TV. The 
easiest would be to just start setting bits in the mask from the start to the
finish and you have a top to bottom wipe. Start at the end of the mask and
you have a bottom to top wipe, or a little tougher one would be a side to side
wipe. Start in the middle of the mask and draw a small circle, then make the
circle larger each time, or use squares, stars or whatever, to create all
different kinds of displays.

	Another effects would be to display one picture and then do a dissolve,
or one of the other effects, to merge in a new picture. This requires that the
new picture has the same attributes (size, colors, ham, etc.) as the current
picture, because you can't change the screen attributes between the pictures.

	If someone was real ambitious they could do a program like Dpslide that
did a lot of different displays with a display list.


	Good Luck,
	Lee M. Robertson 
	( PLINK: lmr )