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[base] New bisecting BBox_Cubic_Check (disabled).

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* src/base/ftbbox.c (BBox_Cubic_Check): New bisecting algorithm
for extremum search built around simple condition that defines
which half contains the extremum.
This commit is contained in:
Alexei Podtelezhnikov 2013-02-19 21:27:18 -05:00
parent 0e536676ba
commit f9434dba81
2 changed files with 90 additions and 47 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2013-02-19 Alexei Podtelezhnikov <apodtele@gmail.com>
[base] New bisecting BBox_Cubic_Check (disabled).
* src/base/ftbbox.c (BBox_Cubic_Check): New bisecting algorithm
for extremum search built around simple condition that defines
which half contains the extremum.
2013-02-18 Alexei Podtelezhnikov <apodtele@gmail.com>
[tools] Update BBox testing tool.

129
src/base/ftbbox.c
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@ -222,65 +222,100 @@
FT_Pos* min,
FT_Pos* max )
{
FT_Pos stack[32*3 + 1], *arc;
FT_Pos q1, q2, q3, q4;
arc = stack;
q1 = p1;
q2 = p2;
q3 = p3;
q4 = p4;
arc[0] = p1;
arc[1] = p2;
arc[2] = p3;
arc[3] = p4;
do
/* for a conic segment to possibly reach new maximum */
/* one of its off-points must be above the current value */
while ( q2 > *max || q3 > *max )
{
FT_Pos y1 = arc[0];
FT_Pos y2 = arc[1];
FT_Pos y3 = arc[2];
FT_Pos y4 = arc[3];
if ( y1 == y4 )
/* determine which half contains the maximum and split */
if ( q1 + q2 > q3 + q4 ) /* first half */
{
if ( y1 == y2 && y1 == y3 ) /* flat */
goto Test;
q4 = q4 + q3;
q3 = q3 + q2;
q2 = q2 + q1;
q4 = q4 + q3;
q3 = q3 + q2;
q4 = ( q4 + q3 ) / 8;
q3 = q3 / 4;
q2 = q2 / 2;
}
else if ( y1 < y4 )
else /* second half */
{
if ( y2 >= y1 && y2 <= y4 && y3 >= y1 && y3 <= y4 ) /* ascending */
goto Test;
}
else
{
if ( y2 >= y4 && y2 <= y1 && y3 >= y4 && y3 <= y1 ) /* descending */
{
y2 = y1;
y1 = y4;
y4 = y2;
goto Test;
}
q1 = q1 + q2;
q2 = q2 + q3;
q3 = q3 + q4;
q1 = q1 + q2;
q2 = q2 + q3;
q1 = ( q1 + q2 ) / 8;
q2 = q2 / 4;
q3 = q3 / 2;
}
/* unknown direction -- split the arc in two */
arc[6] = y4;
arc[1] = y1 = ( y1 + y2 ) / 2;
arc[5] = y4 = ( y4 + y3 ) / 2;
y2 = ( y2 + y3 ) / 2;
arc[2] = y1 = ( y1 + y2 ) / 2;
arc[4] = y4 = ( y4 + y2 ) / 2;
arc[3] = ( y1 + y4 ) / 2;
/* check if either end reached the maximum */
if ( q1 == q2 && q1 >= q3 )
{
*max = q1;
break;
}
if ( q3 == q4 && q2 <= q4 )
{
*max = q4;
break;
}
}
arc += 3;
goto Suite;
q1 = p1;
q2 = p2;
q3 = p3;
q4 = p4;
Test:
if ( y1 < *min ) *min = y1;
if ( y4 > *max ) *max = y4;
arc -= 3;
/* for a conic segment to possibly reach new minimum */
/* one of its off-points must be below the current value */
while ( q2 < *min || q3 < *min )
{
/* determine which half contains the minimum and split */
if ( q1 + q2 < q3 + q4 ) /* first half */
{
q4 = q4 + q3;
q3 = q3 + q2;
q2 = q2 + q1;
q4 = q4 + q3;
q3 = q3 + q2;
q4 = ( q4 + q3 ) / 8;
q3 = q3 / 4;
q2 = q2 / 2;
}
else /* second half */
{
q1 = q1 + q2;
q2 = q2 + q3;
q3 = q3 + q4;
q1 = q1 + q2;
q2 = q2 + q3;
q1 = ( q1 + q2 ) / 8;
q2 = q2 / 4;
q3 = q3 / 2;
}
Suite:
;
} while ( arc >= stack );
/* check if either end reached the minimum */
if ( q1 == q2 && q1 <= q3 )
{
*min = q1;
break;
}
if ( q3 == q4 && q2 >= q4 )
{
*min = q4;
break;
}
}
}
#else