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| maximum size to al_create_bitmap |
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The Master
Member #4,498
April 2004
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Allegro5 question: I'm working on loading a tile set into a single bitmap, and then drawing regions of this bitmap as required. It was the simplest and most straightforward approach. But I seem to be having a problem. I've saved the tile set into a custom format made with TileStudio (which is awesome by the way), and so I've written code that loads it into an Allegro5 bitmap structure. I do this by creating a new bitmap, and then loading the pixel colour components from the file and using al_put_pixel. Now I know this all works, because I've seen it. But it gets to when I'm actually creating the bitmap. Sometimes (most of the time but not all) al_create_bitmap will cause a weird exception to be thrown elsewhere in the program. That is, the code will execute until al_create_bitmap, and then it'll throw an exception. But the call stack will in fact point to a different part of the program (some where inside the NSApplication object - I'm using Mac OS X). I've concluded, but I'm not entirely sure, that this is being caused by me asking for a massive bitmap. 48 tiles, each tile 32x32x32bits. So I was curious if there is an upper limit on the permitted size of a bitmap (independent of the available memory). Let me know We can only do what we feel is right each moment as we live it. |
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Evert
Member #794
November 2000
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The Master said: That is, the code will execute until al_create_bitmap, and then it'll throw an exception. But the call stack will in fact point to a different part of the program (some where inside the NSApplication object - I'm using Mac OS X). That's the main thread, but your program runs from a secondary thread. You need to switch to one of the other threads to find the correct point where the program crashes (I can never quite remember which thread I want, but you can easily tell by trying them all because most of the tracebacks will not make sence). Quote: I've concluded, but I'm not entirely sure, that this is being caused by me asking for a massive bitmap. 48 tiles, each tile 32x32x32bits. So I was curious if there is an upper limit on the permitted size of a bitmap (independent of the available memory). Yes, if it's a video bitmap, it must be smaller than the largest texture size. If you do a 32 by 48*32 bitmap, you may overrun that. This is less likely if you do 3*32 by 16*32. |
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Matthew Leverton
Supreme Loser
January 1999
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You can query the maximum size allowed via al_get_new_display_option with ALLEGRO_MAX_BITMAP_SIZE. Evert said: if you do a 32 by 48*32 bitmap, you may overrun that. This is less likely if you do 3*32 by 16*32. In other words, make your tile bitmap square. The longest side is what determines whether or not it will fit into a video bitmap. The same card that doesn't support 1025x32 might support 1024x1024. |
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The Master
Member #4,498
April 2004
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Well, i think this is worthy of a bug report in the MacOSX port. i'm still having this problem. [EDIT] it's not just appearing in al_create_bitmap. sometimes it shows up in al_set_target_bitmap. sometimes it shows up in al_fclose. We can only do what we feel is right each moment as we live it. |
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Edgar Reynaldo
Major Reynaldo
May 2007
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Post backtraces of when it occurs, and try examining local variables in the line of code that crashes. Also, run a debug version of your program linked to the debugging version of Allegro. That will create an allegro.log file that may have some clues as well. My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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Evert
Member #794
November 2000
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The Master said: Well, i think this is worthy of a bug report in the MacOSX port. i'm still having this problem. There's no OS X specific code in al_create_bitmap(), it's the same code used on other OpenGL-based ports. So if there is a problem with it, it should show up there too. Quote: it's not just appearing in al_create_bitmap. sometimes it shows up in al_set_target_bitmap. sometimes it shows up in al_fclose. That sounds like you are overwriting memory that you shouldn't due to a bad pointer. |
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The Master
Member #4,498
April 2004
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ok, i'll triple check my loading and allocation. might use vectors or something instead of the new operator [EDIT] Now this is freaking weird. I changed my data allocation methods from 'new' to 'std::vector'. and it still shows the same bad alloc error: exact same line number, different code. We can only do what we feel is right each moment as we live it. |
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Edgar Reynaldo
Major Reynaldo
May 2007
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Why don't you post the code you are using? We can't find any errors you might be making without seeing the code you are using. If your code is throwing a std::bad_alloc exception, you are asking for too much memory. Show code. My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
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