Sprite4la	by Dion Vingerhoets	14th April 1994


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	Sprite Version 4 Loading Animation.


	CLI: Sprite4la [path]filename.SpDat


	Remember the old Boing! programs? You know, one or two checkered
 balls bouncing around the screen. Two colored 15 by 15 sprites. Clever,
 but take a look at this tasty. 15 colors, 32 by 32, with gravity equivalent
 to the Moon and a booster when it runs out of bounce.

	For some reason I have found it fun to watch. Having a ball bounce
 smoothly over the screen while I write this does not seem the actions of
 an intelligent man but here I am. Maybe you too will be enchanted.

 TECHNICAL: Four sprites are used. 7 and 6 are linked to form 4 bitplanes
 which are mapped to colors 16 through 31. Sprites 5 and 4 are also linked
 but are positioned 16 pixels to the right of 7 and 6.

 MORE TECHNICAL: Edge detection negates the fraction of x increment on the
 x position which is ±0.1875. The y increment is initially +0.25. The y
 increment is incremented by +0.00061 thus making it fall faster or rise
 slower. This causes the appearance of gravity. Then the increment on the y
 increment is incremented by +0.000244. This causes decay in the balls
 momentum eventually causing rest.

 TECHNICAL DATA: The .SpDat file has a 16 word header as follows :-

 #IMG HGHT SIGN CL20 CL21 CL22 CL23 CL24 CL25 CL26 CL27 CL28 CL29 CL30 CL31

	#IMG = the number of images the animation has.
	HGHT = the number of line in each image. (Sprite height)
	SIGN = Signature which identifies this as a SpDat file.
	CLnn = Color values as 0RGB from 20 to 31

 Next comes the data itself. eg: a 32 wide image with 2 lines of pixel
 colors:
		$FEDCBA98765432100123456789ABCDEF
		$0123456789ABCDEFFEDCBA9876543210

 converts to:

	left image
	;sprite 7		BP1    BP0
			dc.w	$F0F0,$FF00	line 1
			dc.w	$8F0F,$00FF	line 2
	;sprite 6		BP3   BP2
			dc.w	$AAAA,$CCCC	line 1
			dc.w	$D555,$B333	line 2
	right image
	;sprite 5		BP1   BP0
			dc.w	$0F0F,$00FF	line 1
			dc.w	$F0F0,$FF00	line 2
	;sprite 4		BP3   BP2
			dc.w	$5555,$3333	line 1
			dc.w	$AAAA,$CCCC	line 2

 where BPn is the bit plane number of a 16 pixel width bitmap.

	Follow that?

	If you make something amazing, send it to me. If you could not
 follow the explanation but have a sequence of images you'd like to see
 animated, send them to me and I'll do the rest. (Remembering images must
 be limited to 32 pixels wide.)


	Dion Vingerhoets
	  8 AYTON WAY
	DUNCRAIG WA 6023
	(PERTH WEST AUST)

 ps: Double mouse button click will exit the program.


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