MSPRITE (function)

This statement allows you to define a multiplexed sprite. These objects are managed entirely by ugBASIC, and using SPRITE as usual. A multiplexed sprite is a composition of composite sprite where each element of the composition is done by using a virtual sprite that, in turns, use a real (hardware) sprite.

sprites where images are cropped, the size of a multiplexed sprite is taken directly from the image data, and it is rounded to the underlying hardware size (so a 32x32 monochromatic image as above will be converted into 4 hardware sprites of 24x21 pixels). So, if the hardware sprites cannot be resized, a part of the area inside these sprites is wasted, and that you need more than one sprite to represent a large image.

The maximum of eight hardware sprites therefore imposes a strict limit to the number of such objects you can display on a horizontal line. The total width of the objects must not exceed: 24*8=192 pixels (for monochrome sprites) 16*4=96 pixels (for two colors sprites) 16*2=48 pixels (for four colors sprites) 16*1=24 pixels (for eight colors sprites)

If you try to ignore this limitation, you won't get an error message, but your multiplexed sprite will not be displayed on the screen. So it's vital to ensure that the above restriction is respected.

The function accepts the name of a graphic resource, among those previously loaded. This must correspond to a single image: therefore it can be an image or a frame of an ATLAS or a SEQUENCE. The system, in a completely automatic way, will convert the resource into graphic data compatible with the sprite format.

The command accepts a series of parameters, which can be added after the name of the graphic resource. The EXPAND VERTICAL parameter allows you to double the vertical dimensions, making each pixel occupy two or more vertical pixels. On the other hand, the COMPRESS VERTICAL command allows you to restore the original dimensions. The EXPAND HORIZONTAL parameter allows you to double the vertical dimensions, making each pixel occupy two or more vertical pixels. On the other hand, the COMPRESS HORIZONTAL command allows you to restore the original dimensions. Finally, it is possible to indicate one of the colors in the palette as "transparent", and therefore that it does not need to generate a hardware sprite. This can be useful where the graphic resource does not use the color black, which is the standard color to characterize the background. Due to the isomorphic nature of the language, not all flags are usable, or have an effect, on all targets that support sprites.

The function provides additional syntax, valid for redefining a sprite already defined. The purpose of such syntax is to modify the graphic information inherent to a sprite already defined previously, thus being able to dynamically replace the appearance of the sprite. In this case, it is necessary to provide a reference to the previously defined sprite (previous), and ensure that the graphic characteristics (such as the number of colors) are identical.

An additional syntax allows you to "duplicate" a sprite, thus sharing its graphic resources. Simply pass the reference to a previous MSPRITE to define it.

EXAMPLE

 spaceshift = MSPRITE( LOAD IMAGE( "spaceship.png" ) IGNORE COLOR GREEN )
 alien = MSPRITE( LOAD IMAGE( "alien1.png" ) )
 alien = MSPRITE( LOAD IMAGE( "alien2.png" ), alien )