Thanks, Patrick.
Unfortunately when I specify an origin in FT_Glyph_To_Bitmap(),nothing happens.
I've even tried setting it to wacky values, but no effect. So there's no way
to determine the Y offset of the Baseline in an FT_BitmapGlyph?
My sequence of calls basically looks like this:
FT_Set_Char_Size(face, 48*64, 48*64, FONT_DPI, FONT_DPI);
FT_Load_Glyph(face, charIndex, FT_LOAD_DEFAULT);
FT_Get_Glyph(face->glyph, &glyph);
FT_Vector origin = {0, 0};
FT_Glyph_To_Bitmap(&glyph, ft_render_mode_normal, &origin, 1);
I do this for all the glyphs I care about then copy the bitmap buffer to my own
buffer, which then gets stuffed into an OpenGL texture, as shown in the
attachments sent prior.
I'm trying to use the bounding box of each glyph at the moment, but in order to
do so I must INFER where the baseline is. If there were some way to just KNOW
the Y offset of the baseline, I could add the decender value then add the
height and I'd have the correct row offset in my "destination" buffer.
Of course if "origin" did what I expected, it would automatically line
everything up. But it seems to do nothing at all.
Thanks for your help,
Anthony
From: Patrick Baggett [mailto:[email protected]]
Sent: Friday, September 23, 2011 12:58 PM
To: Farmer, Anthony
Cc: [email protected]
Subject: Re: [ft] Rendering problem
The baseline is a point you give. The coordinates for the glyph are relative to
an origin. So the punctuation should be just a small bit off from the baseline.
If you set your baseline to be (0,0), then it bitmap space, you're in the upper
left. Increasing Y moves you down, but in font terms it moves you up (Cartesian
coords). Maybe the difference there has something to do with it. The baseline
for your font really should be lower, say for 16px font, at (x,15).
In other words, if you render a 16pt glyph at (0,0), move over say, 12 pixels
to (12,0), render another 16pt glyph, and so on, you get this:
(0,0) +X
0----------
| G1| G2|
| |---+
|---+
|
+Y
You need to make sure that you actually copy the rendered glyphs to some
position on the bitmap so the bottom of the rect of th glyph is always on teh
baseline, and the baseline should always start at FONT_PIXELS_HEIGHT below 0,
i.e. if your largest font glyph can be 16 pixels tall, you need to use 15 as a
baseline Y so that [0,15] can be filled.
Patrick
http://www.freetype.org/freetype2/docs/glyphs/glyphs-3.html
On Fri, Sep 23, 2011 at 12:12 PM, Farmer, Anthony
<[email protected]<mailto:[email protected]>> wrote:
Hello.
I'm trying to load a font into a bitmap, then into an OpenGL texture for
rendering, and have encountered a problem with the font baseline that I'm
unable to resolve via online documentation or Google search. Attached is a
small bitmap showing what happens, which hopefully obviates what I'm doing
wrong and how it can be corrected.
Briefly, I convert all the glyphs to bitmap glyphs then extract them
sequentially into an OpenGL texture. Later I use the X-offset into that
texture for rendering text. Unfortunately all the punctuation is being placed
at the TOP of the GL texture, as if the baseline were there instead of along
the bottom. I don't believe that's the case, but that's the behavior.
If there were some way I could extract the vertical location of the face's
BASELINE, I could adjust everything accordingly as glyphs are extracted. But I
see no way to get that baseline value.
Or perhaps there's another approach altogether that I should be taking?
Thanks,
Anthony Farmer
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