al_set_new_display_option(3)al_set_new_display_option(3)NAMEal_set_new_display_option - Allegro 5 API
SYNOPSIS
#include <allegro5/allegro.h>
void al_set_new_display_option(int option, int value, int importance)
DESCRIPTION
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_COLOR_SIZE
This can be used to ask for a specific bit depth. For example
to force a 16-bit framebuffer set this to 16.
ALLEGRO_RED_SIZE, ALLEGRO_GREEN_SIZE, ALLEGRO_BLUE_SIZE, ALLE‐
GRO_ALPHA_SIZE
Individual color component size in bits.
ALLEGRO_RED_SHIFT, ALLEGRO_GREEN_SHIFT, ALLEGRO_BLUE_SHIFT, ALLE‐
GRO_ALPHA_SHIFT
Together with the previous settings these can be used to specify
the exact pixel layout the display should use. Normally there
is no reason to use these.
ALLEGRO_ACC_RED_SIZE, ALLEGRO_ACC_GREEN_SIZE, ALLEGRO_ACC_BLUE_SIZE,
ALLEGRO_ACC_ALPHA_SIZE
This 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(3) is equivalent to
al_flip_display(3).
ALLEGRO_VSYNC
Set to 1 to tell the driver to wait for vsync in al_flip_dis‐
play(3), 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 possi‐
ble 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_cre‐
ate_bitmap(3) or al_load_bitmap(3) 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 tex‐
tures will be used internally as bitmap storage.
ALLEGRO_CAN_DRAW_INTO_BITMAP
Set to 1 if you can use al_set_target_bitmap(3) on bitmaps of
this display to draw into them. If this is not the case soft‐
ware 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(3) function is
supported. Otherwise the alpha parameters will be ignored.
SEE ALSOal_set_new_display_flags(3)Allegro reference manualal_set_new_display_option(3)
