Renderer_outline_aa::line3 () Infinite loop

situation One:

The function appears in an infinite loop in the following two-sentence code:

while (ABS (SX-LP.X1) + ABS (SY-LP.Y1) > Lp2.len)
{
SX = (lp.x1 + sx) >> 1;
Sy = (lp.y1 + sy) >> 1;
}

When debugging a breakpoint, the result of an infinite loop is that the value appears as follows:

Sx=0x3d00
Lp.x1=0x3d01
Sy=0x7a00
Lp.y1=0x7a01
Lp2.len=1

in this case, SX and the Sy value is never changed, and the condition of the loop is always set ( While (2>1).

Try modifying the following:

SX = lp.x1 + ((sx-lp.x1) >> 1);
SY = lp.y1 + ((sy-lp.y1) >> 1);

The purpose of the modification is to eventually jump out of the loop. Does not understand the logic of the code.

situation Two:

There is also an infinite loop for the following code:

while (ABS (EX-LP.X2) + ABS (EY-LP.Y2) >
Lp2.len)
{
/* Original
ex = (lp.x2 + ex) >> 1;
EY = (lp.y2 + ey) >> 1;
*/
ex = Lp.x2 + ((ex-lp.x2) >> 1);
EY = Lp.y2 + ((ey-lp.y2) >> 1);

}

situation Three:

Agg_renderer_outline_aa file 1801 Line (Clipbox enabled):

while (ABS (SX-LP.X1) + ABS (SY-LP.Y1) >lp2.len)

{

SX = (lp.x1 + sx) >> 1;

Sy = (lp.y1 + sy) >> 1;

}

SX = 365433

SY =-512

Lp.x1 = 365434

Lp.y1 =-511

Sx/sy always keep the same value: ( -511 + -512) >> 1 =-512;

Modify the following:

while (ABS (SX-LP.X1) + ABS (SY-LP.Y1) > (Lp2.len + 1))
{
...
}

Lp2.len Plus 1 .

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From

Http://vector-agg-general.narkive.com/Zl9USSxj/renderer-outline-aa-line3-infinite-loop-and-fix

Http://vector-agg-general.narkive.com/pJq7asry/infinite-loop-in-renderer-outline-aa

Renderer_outline_aa::line3 () Infinite loop