Sprite visibility

Description

After a sprite has been created, by default it is visible. To control the visible state of a sprite use the command SetSpriteVisible as demonstrated in this example.

Creating a sprite

This block of code creates a sprite using a penguin image:

LoadImage ( 1, "penguin.png" )
CreateSprite ( 1, 1 )
SetSpritePosition ( 1, 100, 300 )

agk::LoadImage ( 1, "penguin.png" );
agk::CreateSprite ( 1, 1 );
agk::SetSpritePosition ( 1, 100, 300 );

Controlling visibility

The command SetSpriteVisible is used to control whether a sprite is visible or invisible, it takes two parameters:

ID - an ID number for a sprite
visible - a value of 0 makes a sprite invisible, while a value of 1 will make the sprite visible

Therefore, to hide our penguin sprite it's a case of calling SetSpriteVisible, setting the first parameter to 1 (ID of the sprite) and its visible state to 0:

SetSpriteVisible ( 1, 0 )

agk::SetSpriteVisible ( 1, 0 );

To retrieve the current visible state of a sprite call the command GetSpriteVisible and pass in the ID of the sprite to check:

visible = GetSpriteVisible ( 1 )

visible = agk::GetSpriteVisible ( 1 );

If the return value is 1 then the sprite is visible. When the return value is 0 the sprite is invisible.

Full code listing

Within the main loop, whenever the user clicks or touches the screen the visibility of the sprite is swapped:

SetVirtualResolution ( 320, 480 )


CreateSprite ( LoadImage ( "background3.jpg" ) )


LoadImage ( 1, "penguin.png" )
CreateSprite ( 1, 1 )
SetSpritePosition ( 1, 100, 300 )


do
    Print ( "Click or touch the screen to" )
    Print ( "hide or show the penguin" )


    if ( GetPointerPressed ( ) = 1 )
	if ( state = 0 )
	    SetSpriteVisible ( 1, 0 )
	    state = 1
	else
	    SetSpriteVisible ( 1, 1 )
            state = 0
	endif
    endif


    Sync ( )
loop

void app::Begin ( void )
{
    agk::SetVirtualResolution ( 320, 480 );


    agk::CreateSprite ( agk::LoadImage ( "background3.jpg" ) );


    agk::LoadImage ( 1, "penguin.png" );
    agk::CreateSprite ( 1, 1 );
    agk::SetSpritePosition ( 1, 100, 300 );
}


void app::Loop ( void )
{
    if ( agk::GetPointerPressed ( ) == 1 )
    {
        if ( state == 0 )
	{
	    agk::SetSpriteVisible ( 1, 0 );
	    state = 1;
	}
	else
	{
	    agk::SetSpriteVisible ( 1, 1 );
	    state = 0;
	}
    }


    agk::Sync ( );
}

Conclusion

Being able to set the visibility of sprites is useful for many in game situations and hiding sprites will also boost performance.