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Commit4ae6967

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Remove copied comments from geo_ops.c source file and replace with new
comments, and cleanup functions. Remove copyright that is no longerrelevant.
1 parent37fc8a6 commit4ae6967

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1 file changed

+73
-75
lines changed

1 file changed

+73
-75
lines changed

‎src/backend/utils/adt/geo_ops.c

Lines changed: 73 additions & 75 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/geo_ops.c,v 1.95 2007/02/27 23:48:08 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/geo_ops.c,v 1.96 2007/03/05 23:29:14 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -5063,128 +5063,126 @@ poly_circle(PG_FUNCTION_ARGS)
50635063
***********************************************************************/
50645064

50655065
/*
5066-
*Test to see if the point is inside the polygon.
5067-
*Code adapted from integer-based routines in WN: A Server for the HTTP
5066+
*Test to see if the point is inside the polygon, returns 1/0, or 2 if
5067+
*the point is on the polygon.
5068+
*Code adapted but not copied from integer-based routines in WN: A
5069+
*Server for the HTTP
50685070
*version 1.15.1, file wn/image.c
5069-
*GPL Copyright (C) 1995 by John Franks
50705071
*http://hopf.math.northwestern.edu/index.html
50715072
*Description of algorithm: http://www.linuxjournal.com/article/2197
5073+
* http://www.linuxjournal.com/article/2029
50725074
*/
50735075

5074-
#defineHIT_IT INT_MAX
5076+
#definePOINT_ON_POLYGON INT_MAX
50755077

50765078
staticint
50775079
point_inside(Point*p,intnpts,Point*plist)
50785080
{
50795081
doublex0,
50805082
y0;
5081-
doublepx,
5082-
py;
5083-
inti;
5083+
doubleprev_x,
5084+
prev_y;
5085+
inti=0;
50845086
doublex,
50855087
y;
5086-
intcross,
5087-
crossnum;
5088-
5089-
/*
5090-
* We calculate crossnum, which is twice the crossing number of a
5091-
* ray from the origin parallel to the positive X axis.
5092-
* A coordinate change is made to move the test point to the origin.
5093-
* Then the function lseg_crossing() is called to calculate the crossnum of
5094-
* one segment of the translated polygon with the ray which is the
5095-
* positive X-axis.
5096-
*/
5088+
intcross,total_cross=0;
50975089

5098-
crossnum=0;
5099-
i=0;
51005090
if (npts <=0)
51015091
return0;
51025092

5093+
/* compute first polygon point relative to single point */
51035094
x0=plist[0].x-p->x;
51045095
y0=plist[0].y-p->y;
51055096

5106-
px=x0;
5107-
py=y0;
5097+
prev_x=x0;
5098+
prev_y=y0;
5099+
/* loop over polygon points and aggregate total_cross */
51085100
for (i=1;i<npts;i++)
51095101
{
5102+
/* compute next polygon point relative to single point */
51105103
x=plist[i].x-p->x;
51115104
y=plist[i].y-p->y;
51125105

5113-
if ((cross=lseg_crossing(x,y,px,py))==HIT_IT)
5106+
/* compute previous to current point crossing */
5107+
if ((cross=lseg_crossing(x,y,prev_x,prev_y))==POINT_ON_POLYGON)
51145108
return2;
5115-
crossnum+=cross;
5116-
5117-
px=x;
5118-
py=y;
5109+
total_cross+=cross;
5110+
5111+
prev_x=x;
5112+
prev_y=y;
51195113
}
5120-
if ((cross=lseg_crossing(x0,y0,px,py))==HIT_IT)
5114+
5115+
/* now do the first point */
5116+
if ((cross=lseg_crossing(x0,y0,prev_x,prev_y))==POINT_ON_POLYGON)
51215117
return2;
5122-
crossnum+=cross;
5123-
if (crossnum!=0)
5118+
total_cross+=cross;
5119+
5120+
if (total_cross!=0)
51245121
return1;
51255122
return0;
51265123
}
51275124

51285125

51295126
/* lseg_crossing()
5130-
* The function lseg_crossing() returns +2, or -2 if the segment from (x,y)
5131-
* to previous (x,y) crosses the positive X-axis positively or negatively.
5132-
* It returns +1 or -1 if one endpoint is on this ray, or 0 if both are.
5133-
* It returns 0 if the ray and the segment don't intersect.
5134-
* It returns HIT_IT if the segment contains (0,0)
5127+
* Returns +/-2 if line segment crosses the positive X-axis in a +/- direction.
5128+
* Returns +/-1 if one point is on the positive X-axis.
5129+
* Returns 0 if both points are on the positive X-axis, or there is no crossing.
5130+
* Returns POINT_ON_POLYGON if the segment contains (0,0).
5131+
* Wow, that is one confusing API, but it is used above, and when summed,
5132+
* can tell is if a point is in a polygon.
51355133
*/
51365134

51375135
staticint
5138-
lseg_crossing(doublex,doubley,doublepx,doublepy)
5136+
lseg_crossing(doublex,doubley,doubleprev_x,doubleprev_y)
51395137
{
51405138
doublez;
5141-
intsgn;
5142-
5143-
/* If (px,py) = (0,0) and not first call we have already sent HIT_IT */
5139+
inty_sign;
51445140

51455141
if (FPzero(y))
5146-
{
5147-
if (FPzero(x))
5148-
{
5149-
returnHIT_IT;
5150-
5151-
}
5142+
{/* y == 0, on X axis */
5143+
if (FPzero(x))/* (x,y) is (0,0)? */
5144+
returnPOINT_ON_POLYGON;
51525145
elseif (FPgt(x,0))
5153-
{
5154-
if (FPzero(py))
5155-
returnFPgt(px,0) ?0 :HIT_IT;
5156-
returnFPlt(py,0) ?1 :-1;
5157-
5146+
{/* x > 0 */
5147+
if (FPzero(prev_y))/* y and prev_y are zero */
5148+
/* prev_x > 0? */
5149+
returnFPgt(prev_x,0) ?0 :POINT_ON_POLYGON;
5150+
returnFPlt(prev_y,0) ?1 :-1;
51585151
}
51595152
else
5160-
{/* x < 0 */
5161-
if (FPzero(py))
5162-
returnFPlt(px,0) ?0 :HIT_IT;
5153+
{/* x < 0, x not on positive X axis */
5154+
if (FPzero(prev_y))
5155+
/* prev_x < 0? */
5156+
returnFPlt(prev_x,0) ?0 :POINT_ON_POLYGON;
51635157
return0;
51645158
}
51655159
}
5166-
5167-
/* Now we know y != 0;set sgn to sign of y */
5168-
sgn= (FPgt(y,0) ?1 :-1);
5169-
if (FPzero(py))
5170-
returnFPlt(px,0) ?0 :sgn;
5171-
5172-
if (FPgt((sgn*py),0))
5173-
{/* y and py have same sign */
5174-
return0;
5175-
5176-
}
51775160
else
5178-
{/* y and py have opposite signs */
5179-
if (FPge(x,0)&&FPgt(px,0))
5180-
return2*sgn;
5181-
if (FPlt(x,0)&&FPle(px,0))
5182-
return0;
5183-
5184-
z= (x-px)*y- (y-py)*x;
5185-
if (FPzero(z))
5186-
returnHIT_IT;
5187-
returnFPgt((sgn*z),0) ?0 :2*sgn;
5161+
{/* y != 0 */
5162+
/* compute y crossing direction from previous point */
5163+
y_sign=FPgt(y,0) ?1 :-1;
5164+
5165+
if (FPzero(prev_y))
5166+
/* previous point was on X axis, so new point is either off or on */
5167+
returnFPlt(prev_x,0) ?0 :y_sign;
5168+
elseif (FPgt(y_sign*prev_y,0))
5169+
/* both above or below X axis */
5170+
return0;/* same sign */
5171+
else
5172+
{/* y and prev_y cross X-axis */
5173+
if (FPge(x,0)&&FPgt(prev_x,0))
5174+
/* both non-negative so cross positive X-axis */
5175+
return2*y_sign;
5176+
if (FPlt(x,0)&&FPle(prev_x,0))
5177+
/* both non-positive so do not cross positive X-axis */
5178+
return0;
5179+
5180+
/* x and y cross axises, see URL above point_inside() */
5181+
z= (x-prev_x)*y- (y-prev_y)*x;
5182+
if (FPzero(z))
5183+
returnPOINT_ON_POLYGON;
5184+
returnFPgt((y_sign*z),0) ?0 :2*y_sign;
5185+
}
51885186
}
51895187
}
51905188

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