FT_GlyphSlot slot = face->glyph; // a small shortcut
FT_UInt glyph_index;
int pen_x, pen_y, n;
.. initialise library ..
.. create face object ..
.. set character size ..
pen_x = 300;
pen_y = 200;
for ( n = 0; n < num_chars; n++ )
{
// load glyph image into the slot (erase previous one)
error = FT_Load_Char( face, text[n], FT_LOAD_RENDER | FT_LOAD_MONOCHROME );
if (error) continue; // ignore errors
// now, draw to our target surface
my_draw_bitmap( &slot->bitmap,
pen_x + slot->bitmap_left,
pen_y - slot->bitmap_top );
// increment pen position
pen_x += slot->advance.x >> 6;
}
FreeType2 with OpenGL
Author
Hi!!11111
I'm trying to use glBitmap fonts with freetype.
This is actually part of the code (from freetype tutorial)
I'v modified it to go throught each character from 32 to 127 and create opengl displaylist in place if my_draw_bitmap.
The problem is that I get only some extraordinary pixel-figures where can not be seen any characters.
The problem is that I can't get correct conversion for the data from FT_Bitmap to glBitmap.
I'w googled and searched all tutorials but can't get it working. There's not any example for the my_draw_bitmap procedure.
Can anyone help?
Edited by - stefu on March 21, 2002 3:21:03 PM
Hmm, I did something similar a while ago. But I used standard alpha textures instead of GL bitmaps, so that I could get antialiased fonts. The conversion from the FT_Bitmap was straight forward:
The destination texture has a fixed width of 512, so be careful if you want to modify it, don''t forget to adapt the loop. And this thing is not fast, so use it only in a preprocess, not in realtime (or optimize it).
FT_Bitmap *bitmap = ... // source bitmapchar *texture_data = ... // destination alpha texture (512*128)for( y=0; y<bitmap->rows; y++ ) for( x=0; x<bitmap->width; x++ ) texture_data[y*512+x] = bitmap->buffer[y*bitmap->pitch+x]; The destination texture has a fixed width of 512, so be careful if you want to modify it, don''t forget to adapt the loop. And this thing is not fast, so use it only in a preprocess, not in realtime (or optimize it).
Author
Thanks.
The problem was that I didn''t know the bitmap format.
It seems each row must be k*32 bits (dword alignment).
I used k*8 bits, that was wrong.
Also all characters were upside-down.
Here''s the conversion that works now for me
if someone want''s to use Freetype in OpenGL
ps. Can I share fon''t with my app? Is there free font''s to do that? (Just to ake sure font is always available in the same location.)
The problem was that I didn''t know the bitmap format.
It seems each row must be k*32 bits (dword alignment).
I used k*8 bits, that was wrong.
Also all characters were upside-down.
Here''s the conversion that works now for me
if someone want''s to use Freetype in OpenGL base = 0; pixel_height = 18; int error = FT_Init_FreeType( &library ); if ( error ) return; error = FT_New_Face( library, "/usr/share/fonts/truetype/commercial/arial.ttf",0, &face ); if ( error ) return; error = FT_Set_Pixel_Sizes( face, /* handle to face object */ 0, /* pixel_width */ 16 ); /* pixel_height */ FT_GlyphSlot slot = face->glyph; // a small shortcut base = glGenLists(96); // Storage For 96 Characters for ( int n = 0; n < 96; n++ ) { int ch = n+32; // load glyph image into the slot (erase previous one) error = FT_Load_Char( face, ch, FT_LOAD_RENDER|FT_LOAD_MONOCHROME); if (error) continue; // ignore errors char bmp[64*64]; // be carrefull!!! memset(bmp,0,sizeof(bmp)); for(int y=0; y<slot->bitmap.rows; y++) { int dst_pitch = 4; while(slot->bitmap.pitch>dst_pitch) dst_pitch+=4; GLubyte *src_row = slot->bitmap.buffer + y*slot->bitmap.pitch; GLubyte *dst_row = bmp + (slot->bitmap.rows-y-1)*dst_pitch; int src_pitch = slot->bitmap.pitch; for(int x=0; x<src_pitch; x++ ) { dst_row[x] = src_row[x]; } } glNewList(base+n,GL_COMPILE); // bitmap is a binary image glBitmap(slot->bitmap.width, slot->bitmap.rows, -slot->bitmap_left, slot->bitmap.rows-slot->bitmap_top, (slot->advance.x>>6), (slot->advance.y>>6), bmp ); glEndList(); } ps. Can I share fon''t with my app? Is there free font''s to do that? (Just to ake sure font is always available in the same location.)
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