ALLEGRO_RENDER_STATE - Man Page

#include <allegro5/allegro.h>

typedef enum ALLEGRO_RENDER_STATE {

Possible render states which can be set with al_set_render_state(3):

ALLEGRO_ALPHA_TEST

If this is set to 1, the values of ALLEGRO_ALPHA_FUNCTION and ALLEGRO_ALPHA_TEST_VALUE define a comparison function which is performed on the alpha component of each pixel. Only if it evaluates to true the pixel is written. Otherwise no subsequent processing (like depth test or blending) is performed. This can be very useful, for example if a depth buffer is used but you do not want fully transparent pixels to modify it.

ALLEGRO_ALPHA_FUNCTION

One of ALLEGRO_RENDER_FUNCTION(3), only used when ALLEGRO_ALPHA_TEST is 1.

ALLEGRO_ALPHA_TEST_VALUE

Only used when ALLEGRO_ALPHA_TEST is 1. Should be a value of 0 - 255.

ALLEGRO_WRITE_MASK

This determines how the framebuffer and depthbuffer are updated whenever a pixel is written (in case alpha and/or depth testing is enabled: after all such enabled tests succeed). Depth values are only written if ALLEGRO_DEPTH_TEST is 1, in addition to the write mask flag being set.

ALLEGRO_DEPTH_TEST

If this is set to 1, compare the depth value of any newly written pixels with the depth value already in the buffer, according to ALLEGRO_DEPTH_FUNCTION. Allegro primitives with no explicit z coordinate will write a value of 0 into the depth buffer.

ALLEGRO_DEPTH_FUNCTION

One of ALLEGRO_RENDER_FUNCTION(3), only used when ALLEGRO_DEPTH_TEST is 1.

5.1.2

al_set_render_state(3), ALLEGRO_RENDER_FUNCTION(3), ALLEGRO_WRITE_MASK_FLAGS(3)

al_attach_shader_source(3), al_set_render_state(3).