A sprite is a visible, movable, animatable object which contains one or more frames in a uniform size. It is often used to represent dynamic object, such as player role, NPC, enemy, or even a short period animated effect etc.

Sprite is loaded by LOAD_RESOURCE or LOAD_BLANK. The former function loads already edited sprite asset from disk, the latter loads blank for runtime accessing only.



The beginning index of sprite frame is 1, exactly the same as what you see in the sprite editor. You can assign interval for each frame respectively in the editor, and set tag as string as well.

There are state-oriented operations and stateless ones, in this guide, the term "state" means some status or condition stored in a sprite object.

These functions are used to manipulate the states of a sprite, read the manual for details about parameters.

PLAY(spr, b = -1, e = -1, loop = TRUE, init = FALSE): plays a range of frames of a sprite, this is state-oriented because it must be stored somewhere of whether a sprite is being played, current frame, etc. Pass frame indexes to it; you can also pass frame tags to play a range of frames, it's helpful when you'd removed or inserted a frame, and won't need to change the indexes in code.

STOP(spr): the function name explains itself.

FLIP_X(spr, f = FALSE): sets whether flipping a sprite horizontally.

FLIP_Y(spr, f = FALSE): sets whether flipping a sprite vertically.

Assuming we got the following tank sprite, (notice the blue spot):



By flipping x:


It becomes:



By flipping y:


It becomes:



By flipping x and y together:


It becomes:



SET_FLIP_CONDITION(spr, fx, fy): sets the flipping condition of a sprite. Sprite is rendered by SPR or SSPR with x and y position. This function is used to mark it automatically flipping when a sprite moves. Read the manual for details about parameters.

Try the following code and see how it behaves, the gun barrel cannot yet flip correctly at horizon, this code only shows how it works:

SPR spr, x, y, r = 0: renders a sprite.

SSPR spr, sx, sy, sw, sh, x, y [, w [, h, r = 0]]: similar to the above one, but can render with only a sub area of a sprite, also can stretch to a different target area.

Try the following code to see how it rotates with parameter r:




Try the following code to make a properly rotating tank:

It maybe appropriate to use rotation for object moves all directions around; and use flipping for object moves either horizontally or vertically.

These functions are used to get and set pixels of sprite. They apply to sprites from both disk assets or dynamic. Read the manual for details:

• SGET spr, i, x, y
  
• SGET spr, i, what
  
• SSET spr, i, x, y, v
  
• SSET spr, i, what, v

SET_ORDERBY(drv, rule ...): sets ordering rules of graphics commands; defaults to "nil" without calling this function. rule ... can be one or more in "nil", "map", "spr", "all"; "all" is shortcut to "spr" and "map", I'll only explain "spr" in this guide.

Sometimes we need to specify rendering orders of multiple objects, it is possible to simply achieve this modifying few lines of code. After calling the above function with a "spr" argument, BASIC8 will automatically sort all sprites according to their y positions. Try the following code:


Move your tank around to see how it sorts.

STEP_ON(y): creates a "step on" non-referenced value, which represents for aligning a sprite's bottom edge to y. Normal position arguments passed to SPR and SSPR denote for the top-left coner of a sprite, use this functions to denote for the bottom edge at y-axis. For example, try following code: