FADING TUTORIAL

The program I have written for this tutorial may not be the only way to fade the screen, but it is the way I use and is relatively simple to accomplish.  The tutorial shows fading to black and white and also a spotlight, where there is a small area of the screen showing, with a circular shading pattern, with the rest of the screen blacked out.  Fades are not limited to this, however.  To fade to different colours, eg red, then all you need do is follow the tutorial for fading to black, but do not increment the red component of the GsBOXF variable used to fade the screen.  This way blue and green will be faded out, leaving red on the screen.  The same can be done with the spotlight - by decreasing, say, the blue component's value, less blue will be faded out, so the light will look more blue.



An explanation of the Semi-transparency options:


0: 0.5 Back + 0.5 Front - 
			takes 50% of the rgb values of the background and adds them to 50% of the
			rgb values of the semi-transparent object.
			  eg - Front(rgb = 100, 50, 30) Back(rgb = 50, 20, 40) = Result(rgb = 75, 35, 35)

1: 1.0 Back + 1.0 Front -
			takes the full rgb values of both the background and the object and adds
			them together, with the highest value being 255.
			  eg - Front(rgb = 50, 75, 240) Back(rgb = 75, 100, 45) = Result(rgb = 125, 175, 255)

2: 1.0 Back - 1.0 Front -
			takes the full rgb value of the object and subtracts it from the full rgb
			value of the background, with the lowest value being 0.
			  eg - Front(rgb = 70, 65, 60) Back(rgb = 60, 70, 125) = Result(rgb = 0, 5, 65)

3: 1.0 Back + 0.25 Front -
			the full value of the rgb of the background and adds it to 25% of the rgb of
			the object.
			  eg - Front(rgb = 100, 60, 40) Back(rgb = 20, 35, 120) = Result(rgb = 45, 50, 130)


While 0 is usually used for everyday semi-transpaency, 1, 2 and 3 are more specialised.  1 can be used (as in my tutorial) to saturate colours, like fading to white, while 2 does the opposite, reducing colour elements to either make other colours more pronounced (eg, make the screen mor red) or to fade to black).  Transparency option 3 can be used to create very faint objects, like a water surface, etc.




Other points to note:

When converting from a bmp to tim, you must check the 'translucent except for black box'
The spotlight should be drawn as a negative (the darkest parts being white) because of the transparency settings.


Any problems, email <shaunyg@hotmail.com> and I will attempt to answer your queries.