Hi, i'm trying to add support for bitmap fonts my app, 3DGS Easy Scripter. TrueType fonts are no problem but i'm unsure exactly how bitmap fonts work.

Is there an algorithm or something? What is the significance of the size having to be excatly 11, 128 or 256 times bigger?

Thanks.

imagine a bitmap font just as a big Bitmap containing a collection of 11, 128 or 256 bitmaps.

Each single bitmap contains an ASCII code, and each one has the same height and width.

If a bitmap font contains 11 characters (0-9 and a space), the bitmaps are orderd in one line, therefore the size of the bitmap is exactly: 11*X_SIZE | Y_SIZE.
If a bitmap font contains 256 characters (all ASCII values), the bitmaps are orderd in 8 lines and 32 rows (resulting in the size of 32*X_SIZE | Y_SIZE*8).

When displaying e.g. the text "ABC" the engine checks the ASCII value of "A" (65) and then just displays the content of the 65 character in the bitmap font ==> (the one in the 3 line, 1 row (32+32+1)).

More: http://en.wikipedia.org/wiki/Computer_font (bitmap font)

hmmm ok thanks for the info. How can i tell the size of each individual character?

I know by looking at a (0-9) font, then each character is 1/11th the pixels of the width of the bitmap. But what about 32*4 or 32*8?

How can I automate the process.

Thanks.

1. ask jcl how they are distinguishing this in the engine
2. perform an aspect check. If the aspect appears to become nonsense, it's probably 32x8 instead of 32x4

The mathematics should not require the IQ of a genius.

A row in a font bitmap contains either 11, or 32 characters. Thus, when the width is divisible by 11, then the character width is 1/11 the bitmap width. Otherwise it's 1/32 the bitmap width.

In the first case the character height is the same as the bitmap height, in the second case it's 1/4 or 1/8 the bitmap height, dependent on whether the bitmap width is more than 4 times its height, or not.

OK, It's still a bit confusing.
When does your engine decide it has 4 rows of characters or 8 rows of characters.

Because the old c-script way my 128 character font of 448 * 112 Pixels.
ie. 14*28 per character, worked correctly, because you could specify width and height of chars.

Now with lite-c you can't specify width and heigth, and the above fon't doesn't display correctly anymore. I can only assume the engine thinks its an 8 row font now! Which it isn't.
To fix this I had to bring the aspect ratio up over 0.5
to 16*28 per character.

The documentation doesn't tell us how the engine decides what is 4 rows or 8 rows, and broke most of my fonts after converting to lite-c.

Please put this info in the manual, to prevent trial and error design in future.

Jethro.

As I said: It's dependent on whether the bitmap width is more than 4 times its height, or not. This was added to the manual.