Sprite.HidePart of Sprite module

Syntax   Sprite.Hide (spriteID : int)

Description   Hides a previously visible sprite. Sprite.Hide has no effect if the sprite is already invisible.

Example   The following program animates four balls on the screen. When the balls are close to each other or to a wall, they appear, otherwise they are hidden.

        var pic, sprite, x, y, dx, dy, radius : array 1 .. 6 of int
        var visible : array 1 .. 6 of boolean
        
        setscreen ("nocursor")
        
        % Create all the sprites.
        for i : 1 .. 6
            radius (i) := Rand.Int (10, 25)
            Draw.FillOval (25, 25, radius (i), radius (i), 8 + i)
            Font.Draw (intstr (i), 20, 20, 0, black)
            pic (i) := Pic.New (0, 0, 50, 50)
            Draw.FillBox (0, 0, 50, 50, 0)
            x (i) := Rand.Int (radius (i), maxx ‹ radius (i))
            y (i) := Rand.Int (radius (i), maxy ‹ radius (i))
            dx (i) := Rand.Int (3, 3)
            dy (i) := Rand.Int (3, 3)
            sprite (i) := Sprite.New (pic (i))
            Sprite.SetPosition (sprite (i), x (i), y (i), true)
            Sprite.SetHeight (sprite (i), i)
            visible (i) := false
        end for
        
        % Now move all the sprites around the screen.
        loop
            for i : 1 .. 6
                if x (i) + dx (i) < radius (i) or
                        x (i) + dx (i) > maxx  radius (i) then
                    dx (i) := dx (i)
                end if
                x (i) := x (i) + dx (i)
                if y (i) + dy (i) < radius (i) or
                        y (i) + dx (i) > maxy  radius (i) then
                    dy (i) := dy (i)
                end if
                y (i) := y (i) + dy (i)
            end for
            for i : 1 .. 6
                var near : boolean := false
                if (x (i) < 50) or (x (i) > maxx  50) or
                        (y (i) < 50) or (y (i) > maxy  50) then
                    near := true
                end if
                if not near then
                    for j : 1 .. 6
                        if i not= j then
                            if sqrt ( (x (i) ‹ x (j)) ** 2 +
                                (y (i) ‹ y (j)) ** 2) < 100 then
                                near := true
                                exit
                            end if
                        end if
                    end for
                end if
                if near and not visible (i) then
                    Sprite.Show (sprite (i))
                    visible (i) := true
                elsif not near and visible (i) then
                    Sprite.Hide (sprite (i))
                    visible (i) := false
                end if
                Sprite.SetPosition (sprite (i), x (i), y (i), true)
            end for
            Time.Delay (40)
            exit when hasch
        end loop
        for i : 1 .. 6
            Sprite.Free (sprite (i))
        end for
Status   Exported qualified.

This means that you can only call the function by calling Sprite.Hide, not by calling Hide.

See also   Sprite.Show.