ALLEGRO_VERTEX_ELEMENT(3)ALLEGRO_VERTEX_ELEMENT(3)NAMEALLEGRO_VERTEX_ELEMENT - Allegro 5 API
SYNOPSIS
#include <allegro5/allegro_primitives.h>
typedef struct ALLEGRO_VERTEX_ELEMENT ALLEGRO_VERTEX_ELEMENT;
DESCRIPTION
A small structure describing a certain element of a vertex. E.g. the
position of the vertex, or its color. These structures are used by the
al_create_vertex_decl function to create the vertex declaration. For
that they generally occur in an array. The last element of such an
array should have the attribute field equal to 0, to signify that it is
the end of the array. Here is an example code that would create a dec‐
laration describing the ALLEGRO_VERTEX structure (passing this as ver‐
tex declaration to al_draw_prim would be identical to passing NULL):
/* On compilers without the offsetof keyword you need to obtain the
* offset with sizeof and make sure to account for packing.
*/
ALLEGRO_VERTEX_ELEMENT elems[] = {
{ALLEGRO_PRIM_POSITION, ALLEGRO_PRIM_FLOAT_3, offsetof(ALLEGRO_VERTEX, x)},
{ALLEGRO_PRIM_TEX_COORD_PIXEL, ALLEGRO_PRIM_FLOAT_2, offsetof(ALLEGRO_VERTEX, u)},
{ALLEGRO_PRIM_COLOR_ATTR, 0, offsetof(ALLEGRO_VERTEX, color)},
{0, 0, 0}
};
ALLEGRO_VERTEX_DECL* decl = al_create_vertex_decl(elems, sizeof(ALLEGRO_VERTEX));
Fields:
· attribute - A member of the ALLEGRO_PRIM_ATTR(3) enumeration, speci‐
fying what this attribute signifies
· storage - A member of the ALLEGRO_PRIM_STORAGE(3) enumeration, speci‐
fying how this attribute is stored
· offset - Offset in bytes from the beginning of the custom vertex
structure. C function offsetof is very useful here.
SEE ALSOal_create_vertex_decl(3), ALLEGRO_VERTEX_DECL(3), ALLEGRO_PRIM_ATTR(3),
ALLEGRO_PRIM_STORAGE(3)Allegro reference manualALLEGRO_VERTEX_ELEMENT(3)
