On Fri, Sep 23, 2011 at 3:56 PM, Farmer, Anthony
<[email protected]>wrote:
> 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?
>
What your asking seems to be more of "what is the maximum height of a
character"? FT_Set_Char_Size() does that. Based on the point size (26.6
notation) and the DPI you can calculate it. A point is 1/72 of an inch if I
recall, and DPI is the number of dots (pixels in this case) per inch, so:
*X* points * ( 1 point / 72 inches) * ( *DPI* dots / 1 inch ) = X * DPI / 72
dots. Even the units work out, heh.
FT_Set_Pixel_Sizes() works too, if you're specifying in pixels. I personally
find that to be more useful for things like games where people don't care
about the precise point size of the font.
> ****
>
> ** **
>
> 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.****
>
> **
>
The origin "translates bitmap before rendering". I'm not so sure that is
what you need. I'm actually not positive what effects it would have, though
I do know it isn't necessary to solve this problem.
> **
>
> 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.
>
If you reason about it, for any K point font, there is a maximum Y value for
where to begin that's y(K). It just so happens that y(K) is actually y(K,
DPI) = K * DPI / 72.0. Here is my first thought about the algorithm to place
text
Let M be the maximum height of any glyph when rendered. Use one of the above
methods to define M [1:point size/dpi, 2: explicitly via Set_Pixel_Sizes].
penX <- 0
penY <- M
for each glyph that needs to be rendered
Render the glyph to a bitmap
if penX + bitmap.width > texture.width, then
penX <- 0
penY <- penY + M
end if
CopyRect(penX, penY, //origin inside of texture
0, 0, //origin inside bitmap
bitmap.width, bitmap.height //width/height of bitmap
)
end for
> ****
>
> ** **
>
> 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]> 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****
>
> This e-mail is confidential. If you are not named above as an addressee or
> are not the intended recipient of this e-mail, please notify the sender and
> immediately delete it.
> E-mails are susceptible to data corruption, interception, falsification,
> delay, unauthorised amendment and viruses. You should therefore carry out
> such virus and other checks as you consider appropriate. Cantor Gaming does
> not accept liability for any such events or any consequences thereof in
> respect of e-mails sent or received. Copyright and any other intellectual
> property rights in its contents are the sole property of Cantor Gaming.
> The contents of e-mails may be monitored for security purposes. Any views
> expressed in this message are those of the individual sender, except where
> the sender specifically states them to be the views of Cantor Gaming.
> This email was sent to you by Cantor Gaming. Cantor Gaming is the trading
> name of Cantor G&W Nevada L.P., a Nevada limited partnership with offices
> located at 135 East 57th Street, New York, New York 10022, and Cantor G&W
> International L.P., a limited partnership registered in England (registered
> number LP010479) with registered office One Churchill Place, Canary Wharf,
> London E14 5RD.****
>
>
> _______________________________________________
> Freetype mailing list
> [email protected]
> https://lists.nongnu.org/mailman/listinfo/freetype****
>
> ** **
> This e-mail is confidential. If you are not named above as an addressee
> or are not the intended recipient of this e-mail, please notify the sender
> and immediately delete it.
> E-mails are susceptible to data corruption, interception, falsification,
> delay, unauthorised amendment and viruses. You should therefore carry out
> such virus and other checks as you consider appropriate. Cantor Gaming does
> not accept liability for any such events or any consequences thereof in
> respect of e-mails sent or received. Copyright and any other intellectual
> property rights in its contents are the sole property of Cantor Gaming.
> The contents of e-mails may be monitored for security purposes. Any views
> expressed in this message are those of the individual sender, except where
> the sender specifically states them to be the views of Cantor Gaming.
> This email was sent to you by Cantor Gaming. Cantor Gaming is the trading
> name of Cantor G&W Nevada L.P., a Nevada limited partnership with offices
> located at 135 East 57th Street, New York, New York 10022, and Cantor G&W
> International L.P., a limited partnership registered in England (registered
> number LP010479) with registered office One Churchill Place, Canary Wharf,
> London E14 5RD.
>
_______________________________________________
Freetype mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/freetype
