fixed severe bugs in QuadForPlane (broken axis selection and use of the wrong planeno...

modified Divide to not rotate the point list, this is a minor un-optimization of the algorithm but should improve consistency (unclipped polygons come out the same as they went in)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@4404 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/polygon.c b/polygon.c
index 8133dce3dbd0e99d26dbf705a0b63498c723b12c..1a4f0797aa44639da88f4524c09b0e5bfae4e5df 100644 (file)
--- a/polygon.c
+++ b/polygon.c
@@ -9,7 +9,7 @@ Polygon clipping routines written by Forest Hale and placed into public domain.
 void PolygonF_QuadForPlane(float *outpoints, float planenormalx, float planenormaly, float planenormalz, float planedist, float quadsize)
 {
        float d, quadright[3], quadup[3];
-       if (planenormalz > planenormalx && planenormalz > planenormaly)
+       if (fabs(planenormalz) > fabs(planenormalx) && fabs(planenormalz) > fabs(planenormaly))
        {
                quadup[0] = 1;
                quadup[1] = 0;
@@ -25,8 +25,8 @@ void PolygonF_QuadForPlane(float *outpoints, float planenormalx, float planenorm
        d = -(quadup[0] * planenormalx + quadup[1] * planenormaly + quadup[2] * planenormalz);
        // VectorMA(quadup, d, planenormal, quadup);
        quadup[0] += d * planenormalx;
-       quadup[1] += d * planenormalx;
-       quadup[2] += d * planenormalx;
+       quadup[1] += d * planenormaly;
+       quadup[2] += d * planenormalz;
        // VectorNormalize(quadup);
        d = 1.0 / sqrt(quadup[0] * quadup[0] + quadup[1] * quadup[1] + quadup[2] * quadup[2]);
        quadup[0] *= d;
@@ -54,7 +54,7 @@ void PolygonF_QuadForPlane(float *outpoints, float planenormalx, float planenorm
 void PolygonD_QuadForPlane(double *outpoints, double planenormalx, double planenormaly, double planenormalz, double planedist, double quadsize)
 {
        double d, quadright[3], quadup[3];
-       if (planenormalz > planenormalx && planenormalz > planenormaly)
+       if (fabs(planenormalz) > fabs(planenormalx) && fabs(planenormalz) > fabs(planenormaly))
        {
                quadup[0] = 1;
                quadup[1] = 0;
@@ -70,8 +70,8 @@ void PolygonD_QuadForPlane(double *outpoints, double planenormalx, double planen
        d = -(quadup[0] * planenormalx + quadup[1] * planenormaly + quadup[2] * planenormalz);
        // VectorMA(quadup, d, planenormal, quadup);
        quadup[0] += d * planenormalx;
-       quadup[1] += d * planenormalx;
-       quadup[2] += d * planenormalx;
+       quadup[1] += d * planenormaly;
+       quadup[2] += d * planenormalz;
        // VectorNormalize(quadup);
        d = 1.0 / sqrt(quadup[0] * quadup[0] + quadup[1] * quadup[1] + quadup[2] * quadup[2]);
        quadup[0] *= d;
@@ -103,11 +103,11 @@ void PolygonF_Divide(unsigned int innumpoints, const float *inpoints, float plan
        float frac, pdist, ndist;
        frontcount = 0;
        backcount = 0;
-       p = inpoints + (innumpoints - 1) * 3;
-       n = inpoints;
-       pdist = p[0] * planenormalx + p[1] * planenormaly + p[2] * planenormalz - planedist;
        for (i = 0;i < innumpoints;i++)
        {
+               p = inpoints + i * 3;
+               n = inpoints + ((i + 1) < innumpoints ? (i + 1) : 0) * 3;
+               pdist = p[0] * planenormalx + p[1] * planenormaly + p[2] * planenormalz - planedist;
                ndist = n[0] * planenormalx + n[1] * planenormaly + n[2] * planenormalz - planedist;
                if (pdist >= -epsilon)
                {
@@ -147,9 +147,6 @@ void PolygonF_Divide(unsigned int innumpoints, const float *inpoints, float plan
                        }
                        backcount++;
                }
-               p = n;
-               n += 3;
-               pdist = ndist;
        }
        if (neededfrontpoints)
                *neededfrontpoints = frontcount;
@@ -164,11 +161,11 @@ void PolygonD_Divide(unsigned int innumpoints, const double *inpoints, double pl
        double frac, pdist, ndist;
        frontcount = 0;
        backcount = 0;
-       p = inpoints + (innumpoints - 1) * 3;
-       n = inpoints;
-       pdist = p[0] * planenormalx + p[1] * planenormaly + p[2] * planenormalz - planedist;
        for (i = 0;i < innumpoints;i++)
        {
+               p = inpoints + i * 3;
+               n = inpoints + ((i + 1) < innumpoints ? (i + 1) : 0) * 3;
+               pdist = p[0] * planenormalx + p[1] * planenormaly + p[2] * planenormalz - planedist;
                ndist = n[0] * planenormalx + n[1] * planenormaly + n[2] * planenormalz - planedist;
                if (pdist >= -epsilon)
                {
@@ -208,9 +205,6 @@ void PolygonD_Divide(unsigned int innumpoints, const double *inpoints, double pl
                        }
                        backcount++;
                }
-               p = n;
-               n += 3;
-               pdist = ndist;
        }
        if (neededfrontpoints)
                *neededfrontpoints = frontcount;