The "fire" is returning to (X 0) after it hits the right edge

Question

I'm coding a game where you're a spider and you're trying to avoid fire. I'm coding the fire and when it hits the right edge it returns to the left edge and goes up and down it ad infinitum. I'm using the code from school free software as a base with some modification "bouncing ball animation".

test1.xdest and test1.ydest aren't being called anywhere else but in sub bounce and in the main do loop. I'm not sure why it's doing it.

SCREEN _NEWIMAGE(640, 480, 32)
RANDOMIZE TIMER
TYPE test 'player info
    x AS INTEGER
    y AS INTEGER
END TYPE

TYPE test1 'fire info
    x AS INTEGER
    y AS INTEGER
    xdest AS INTEGER
    ydest AS INTEGER
    number AS INTEGER
    fire AS LONG
END TYPE

DIM SHARED spider AS test
DIM SHARED test1 AS test1
test1.x = 0 'fire x chord
test1.y = 0 'fire y chord

test1.xdest = 1 '1 if fire is moving right 0 left
test1.ydest = 0 '1 up 0 down
test1.fire = _LOADIMAGE("./fire.png")

DO
    PCOPY 1, _DISPLAY
    CLS
    IF _KEYDOWN(18432) THEN spider.y = spider.y - 5
    IF _KEYDOWN(20480) THEN spider.y = spider.y + 5

    IF _KEYDOWN(19200) THEN spider.x = spider.x - 5
    IF _KEYDOWN(19712) THEN spider.x = spider.x + 5
    CIRCLE (spider.x, spider.y), 5, _RGB(177, 83, 127)
    _PUTIMAGE (test1.x, test1.y), test1.fire
    IF test1.xdest = 1 THEN test1.x = test1.x + 5
    IF test1.xdest = 0 THEN test1.x = text1.x - 5

    IF test1.ydest = 1 THEN test1.y = test1.y - 5
    IF test1.ydest = 0 THEN test1.y = test1.y + 5

    bounce
    border

    WAIT &H3DA, &H3DA
    WAIT &H3DA, &H3DA, 8
    _DISPLAY
    PCOPY _DISPLAY, 1
LOOP

SUB bounce 'makes the fire bounce
    IF test1.x >= 628 THEN
        test1.xdest = 0
    END IF
    IF test1.x <= 0 THEN
        text1.xdest = 1
    END IF
    IF test1.y >= 468 THEN
        test1.ydest = 1
    END IF
    IF test1.y <= 0 THEN
        test1.ydest = 0
    END IF
END SUB
SUB border 'prevents palyer from going OOB
    IF spider.x > 630 THEN spider.x = spider.x - 5
    IF spider.x < 0 THEN spider.x = spider.x + 5
    IF spider.y > 470 THEN spider.y = spider.y - 5
    IF spider.y < 0 THEN spider.y = spider.y + 5
END SUB

Answer 1

i figured it out, on line 37, i misspelled one of my variables, i put text1.x instead of test1.x

Answer 2

The problem in this program is that there are a couple of typos.

• On line 37 you erroneously wrote text1.x. Should be test1.x
• On line 56 you erroneously wrote text1.xdest. Should be test1.xdest

---

You can make the code a bit more efficient if you would use ELSE IF:

IF test1.x >= 628 THEN
    test1.xdest = 0
ELSE IF test1.x <= 0 THEN
    test1.xdest = 1
END IF
IF test1.y >= 468 THEN
    test1.ydest = 1
ELSE IF test1.y <= 0 THEN
    test1.ydest = 0
END IF