Hello guys,

I try to use the al_create_sub_bitmap from the my current display but it doesnt work. I constantly have that output:

Assertion failed: bitmap != dest && bitmap != dest->parent, file C:\dev\allegro_winpkg\universal\allegro\src\bitmap_draw.c, line 34

The only I found to bypass this problem is to copy the full display in an another bitmap then make my saving from this saved bitmap. Here is my trick:

1) al_set_target_bitmap(save_bitmap)
2) al_draw_bitmap(display, 0, 0, 0);
3) al_set_target_bitmap(display);
4) al_create_sub_bitmap(save_bitmap, .....);

Could like to bypass all this and use al_create_sub_bitmap directly from display.

Any idea would be appreciated thank you

I am creating a map with tiles.

Lets say that I have one tile representing the ground. The tile next to it will be the coast (composed by half part ground and the other one water). So what I do is:

1) Save half of the ground
2) Paste the ground on water
3) Paste the coast

So I will have at the end a tile composed by ground - coast - water.

So that's why I need to save a region of the display.

I will try the al_draw_bitmap_region and let you know

=> I tried with the al_draw_bitmap_region and still the same:

Assertion failed: bitmap != dest && bitmap != dest->parent, file C:\dev\allegro_winpkg\universal\allegro\src\bitmap_draw.c, line 34

That assertion means that you can't draw a bitmap to itself, it's not specific to the display bitmap. The reason why that's forbidden is because, if I recall correctly, this operation isn't actually hardware accelerated. Basically you want to use an intermediate bitmap (there shouldn't be any speed penalty for this) and you should avoid reading from the display.

Indeed I tried with a temp bitmap and it worked totally fine. Pity that we cant copy directly from the display.

Thanks by the way guys.