al_set_new_display_option

void al_set_new_display_option(int option, int value, int importance) Introduced in 5.0.0

Set an extra display option, to be used when creating new displays on the calling thread. Display options differ from display flags, and specify some details of the context to be created within the window itself. These mainly have no effect on Allegro itself, but you may want to specify them, for example if you want to use multisampling.

The 'importance' parameter can be either:

ALLEGRO_REQUIRE - The display will not be created if the setting can not be met.
ALLEGRO_SUGGEST - If the setting is not available, the display will be created anyway. FIXME: We need a way to query the settings back from a created display.
ALLEGRO_DONTCARE - If you added a display option with one of the above two settings before, it will be removed again. Else this does nothing.

The supported options are:

ALLEGRO_RED_SIZE
ALLEGRO_GREEN_SIZE
ALLEGRO_BLUE_SIZE
ALLEGRO_ALPHA_SIZE
ALLEGRO_COLOR_SIZE
ALLEGRO_RED_SHIFT
ALLEGRO_GREEN_SHIFT
ALLEGRO_BLUE_SHIFT
ALLEGRO_ALPHA_SHIFT: These settings can be used to specify the pixel layout the display should use.
ALLEGRO_ACC_RED_SIZE
ALLEGRO_ACC_GREEN_SIZE
ALLEGRO_ACC_BLUE_SIZE
ALLEGRO_ACC_ALPHA_SIZE: This and the preceding three settings can be used to define the required accumulation buffer size.
ALLEGRO_STEREO: Whether the display is a stereo display.
ALLEGRO_AUX_BUFFERS: Number of auxiliary buffers the display should have.
ALLEGRO_DEPTH_SIZE: How many depth buffer (z-buffer) bits to use.
ALLEGRO_STENCIL_SIZE: How many bits to use for the stencil buffer.
ALLEGRO_SAMPLE_BUFFERS: Whether to use multisampling (1) or not (0).
ALLEGRO_SAMPLES: If the above is 1, the number of samples to use per pixel. Else 0.
ALLEGRO_RENDER_METHOD: 0 if hardware acceleration is not used with this display.
ALLEGRO_FLOAT_COLOR: Whether to use floating point color components.
ALLEGRO_FLOAT_DEPTH: Whether to use a floating point depth buffer.
ALLEGRO_SINGLE_BUFFER: Whether the display uses a single buffer (1) or another update method (0).
ALLEGRO_SWAP_METHOD: If the above is 0, this is set to 1 to indicate the display is using a copying method to make the next buffer in the flip chain available, or to 2 to indicate a flipping or other method.
ALLEGRO_COMPATIBLE_DISPLAY: Indicates if Allegro's graphics functions can use this display. If you request a display not useable by Allegro, you can still use for example OpenGL to draw graphics.
ALLEGRO_UPDATE_DISPLAY_REGION: Set to 1 if the display is capable of updating just a region, and 0 if calling al_update_display_region is equivalent to al_flip_display.
ALLEGRO_VSYNC: Set to 1 to tell the driver to wait for vsync in al_flip_display, or to 2 to force vsync off. The default of 0 means that Allegro does not try to modify the vsync behavior so it may be on or off. Note that even in the case of 1 or 2 it is possile to override the vsync behavior in the graphics driver so you should not rely on it.
ALLEGRO_MAX_BITMAP_SIZE: When queried this returns the maximum size (width as well as height) a bitmap can have for this display. Calls to al_create_bitmap or al_load_bitmap for bitmaps larger than this size will fail. It does not apply to memory bitmaps which always can have arbitrary size (but are slow for drawing).
ALLEGRO_SUPPORT_NPOT_BITMAP: Set to 1 if textures used for bitmaps on this display can have a size which is not a power of two. This is mostly useful if you use Allegro to load textures as otherwise only power-of-two textures will be used internally as bitmap storage.
ALLEGRO_CAN_DRAW_INTO_BITMAP: Set to 1 if you can use al_set_target_bitmap on bitmaps of this display to draw into them. If this is not the case software emulation will be used when drawing into display bitmaps (which can be very slow).
ALLEGRO_SUPPORT_SEPARATE_ALPHA: This is set to 1 if the al_set_separate_blender function is supported. Otherwise the alpha parameters will be ignored.

FIXME: document them all in detail

Manual

Display routines

al_set_new_display_option