Designing Games with Game Maker - YoYo Games

sprite_get_texture(spr,subimg) Returns the id of the texture
corresponding to subimage subimg of the indicated sprite.
background_get_texture(back) Returns the id of the texture
corresponding to the indicated background.
A selected texture might not yet be in video memory. The system will put it there once you
need it but sometimes you want to decide this yourself. For this the following two functions
exist:
texture_preload(texid) Puts the texture immediately into video memory.
texture_set_priority(texid,prio) When there is too little video
memory some will be removed temporarily to make room for others that are
needed. The ones with lowest priority are removed first. Default, all have
priority 0 but you can change the priority here. (Use positive values!)
To add textures to primitives you must specify which parts of the textures must be put where
on the primitive. Positions in the texture are indicated with values between 0 and 1 but there
is a problem here. Sizes of textures must be powers of 2 (so e.g. 32x32 or 64x64). If you
want to use sprites or background as textures you better make sure they have such a size. If
not, the test will be blank. To find out which part of the texture is actually used you can use
the following two functions. They return a value between 0 and 1 that indicates the width or
height of the actual part of the texture being used. Specifying this value as texture coordinate
will indicate the right or bottom side of the texture.
texture_get_width(texid) Returns the width of the texture with the
given id. The width lies in the range 0-1.
texture_get_height(texid) Returns the height of the texture with the
given id. The height lies in the range 0-1.
To draw textured primitives you use the following functions:
draw_primitive_begin_texture(kind,texid) Start a primitive of the
indicated kind with the given texture.
draw_vertex_texture(x,y,xtex,ytex) Add vertex (x,y) to the primitive
with position (xtex,ytex) in the texture, blending with the color and alpha
value set before. xtex and ytex should normally lie between 0 and 1 but also
larger values can be used, leading to a repetition of the texture (see below).