TI99 Environment

CALL_POSITIONX and CALL_POSITIONY

Syntax

integer-variable = CALL_POSITIONX(sprite-number)

integer-variable = CALL_POSITIONY(sprite-number)

Description

The CALL_POSITIONX function returns the x position of sprite sprite-number.
The CALL_POSITIONY function returns the y position of sprite sprite-number.

The position returned is the upper left corner of the sprite. If the sprite is set in auto-motion, it will continue to move after its position is returned, so that must be allowed for; the distance it moves depends on the sprite's velocity.

Valid function values CALL_POSITIONX():
sprite-number: accepts an integer between 1-maxsprites.
integer-variable: returns a value between 1 and 256.

Valid function values CALL_POSITIONY():
sprite-number: accepts an integer between 1-maxsprites.
integer-variable: returns a value between 1 and 256 (positions 193-256 are not visible on the screen).

Example Code

call_screen(15)
mgn = 4 : call_magnify(mgn)
sx = 1 : sy = 1 : dly = 25
a$ = rpt$("f",63)+"e" : call_char(128,a$)
display_at(1,1,"Arrows-Move,ENTER-Chng size",0)
call_sprite(1,128,rnd(12) + 2,sy,sx,0,0) ` Displays sprites   
do        
    cslx = CALL_POSITIONX(1)
    csly = CALL_POSITIONY(1)
    display_at(23,2,"X:" + str$(cslx) + "   Y:" + str$(csly)+ "   MAG:" + str$(mgn),0)
    tiwait(dly)    
    if upkey() then dy = -1 
    if downkey() then dy = 1
    if leftkey() then dx = -1
    if rightkey() then dx = 1
    if inkey$() = chr$(13) 
        inc mgn : tiwait(dly)
        if mgn > 4 then mgn = 1 
        call_magnify(mgn)
    ENDIF
    if sx + dx > swidth then sx = 1 : dx = 0
    if sx + dx < 1 then sx = swidth : dx =0
    if sy + dy > swidth then sy = 1 : dy = 0
    if sy + dy < 1 then sy = swidth : dy =0
    inc sx,dx : inc sy,dy : dx = 0 : dy = 0
    call_locate(1,sy,sx)
loop

Program Explanation:
The above program displays the sprite coordinates as it is moved using the arrow keys. 
It also allows the user to cycle through different magnification levels when the Enter key is pressed.

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