I'm working on a small project using Allegro 5, and I've encountered a problem when rendering text using a TTF font under what seems like very specific circumstances.
Put simply, if I enable mipmapping and then try to draw text using a loaded TTF font, nothing seems to actually be drawn. The problem only occurs with TTF fonts (bitmap fonts work fine) and moreover, only while using the OpenGL driver (D3D works fine, too).
I'm using Allegro 5.0.0 RC3 with Visual Studio 2008 under Windows 7 64-bit. The graphics card is a NVIDIA GeForce 9800 GTX+, driver version 258.96.
I've tried reproducing it on a different computer under Ubuntu 10.04 32-bit, where drawing works both with and without mipmapping. I'm not very familiar with linux on the whole so I'm not certain what other information would be helpful, nor do I know offhand what hardware the machine has, aside from an ATI graphics card.
Here is a small test program I made along with a screenshot of the four test results. The resources used are from the examples bundled with Allegro 5.
#SelectExpand
1#include <allegro5/allegro.h>
2#include <allegro5/allegro_font.h>
3#include <allegro5/allegro_ttf.h>
4#include <allegro5/allegro_image.h>
5
6//#define USE_OPENGL
7//#define USE_MIPMAP
8
9int main
()
10{
11 al_init();
12 al_install_keyboard();
13
14#ifdef USE_OPENGL
15 al_set_new_display_flags(ALLEGRO_WINDOWED
| ALLEGRO_OPENGL
);
16#else
17 al_set_new_display_flags(ALLEGRO_WINDOWED
| ALLEGRO_DIRECT3D_INTERNAL
);
18#endif
19
20 ALLEGRO_DISPLAY* display
= al_create_display(480,
128);
21
22#ifdef USE_OPENGL
23# ifdef USE_MIPMAP
24 al_set_window_title(display,
"OpenGL (using mipmaps)");
25# else
26 al_set_window_title(display,
"OpenGL (no mipmaps)");
27# endif
28#else
29# ifdef USE_MIPMAP
30 al_set_window_title(display,
"D3D (using mipmaps)");
31# else
32 al_set_window_title(display,
"D3D (no mipmaps)");
33# endif
34#endif
35
36 al_init_image_addon();
37 al_init_font_addon();
38 al_init_ttf_addon();
39
40#ifdef USE_MIPMAP
41 al_set_new_bitmap_flags(al_get_new_bitmap_flags() | ALLEGRO_MIPMAP
);
42#endif
43
44 ALLEGRO_FONT* font_ttf
= al_load_font("DejaVuSans.ttf",
36,
0);
45 ALLEGRO_FONT* font_bmp
= al_load_font("bmpfont.tga",
0,
0);
46
47 while (true)
48 {
49 ALLEGRO_KEYBOARD_STATE keyboard_state
;
50 al_get_keyboard_state(&keyboard_state
);
51
52 if (al_key_down(&keyboard_state, ALLEGRO_KEY_ESCAPE
))
53 break;
54
55 al_clear_to_color(al_map_rgb(128,
192,
225));
56
57 al_draw_text(font_ttf,
al_map_rgb(255,
255,
255),
10.
0f,
10.
0f, ALLEGRO_ALIGN_LEFT,
"Lorem ipsum");
58 al_draw_text(font_bmp,
al_map_rgb(255,
255,
255),
10.
0f,
60.
0f, ALLEGRO_ALIGN_LEFT,
"Lorem ipsum");
59
60 al_flip_display();
61 }
62
63 al_destroy_font(font_ttf
);
64 al_destroy_font(font_bmp
);
65
66 al_destroy_display(display
);
67}
{"name":"Z9t9a.png","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/2\/0\/20e3c6b616c8a07e430f4ff9b35e8dbc.png","w":496,"h":664,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/2\/0\/20e3c6b616c8a07e430f4ff9b35e8dbc"}
Any help would be greatly appreciated.
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