[Teem-commit] SF.net SVN: teem:[7139] teem/trunk/src/seek

[<kin...@us...>]

Revision: 7139
          http://sourceforge.net/p/teem/code/7139
Author:   kindlmann
Date:     2023-07-22 05:08:53 +0000 (Sat, 22 Jul 2023)
Log Message:
-----------
bug fix in sctx->gradMagAvg computation, and improved descriptive comment in seek.h

Modified Paths:
--------------
    teem/trunk/src/seek/extract.c
    teem/trunk/src/seek/seek.h

Modified: teem/trunk/src/seek/extract.c
===================================================================
--- teem/trunk/src/seek/extract.c	2023-07-22 04:00:51 UTC (rev 7138)
+++ teem/trunk/src/seek/extract.c	2023-07-22 05:08:53 UTC (rev 7139)
@@ -836,7 +836,8 @@
               ELL_3V_LERP(grad, ww, vgrad[vi0], vgrad[vi1]);
               ELL_3MV_MUL(tvec, sctx->txfNormal, grad);
               ELL_3V_NORM_TT(lpld->norm + 3 * ovi, float, tvec, tlen);
-              sctx->gradMagAvg += tlen;
+              /* need to /2 because vgrad were found by central differences */
+              sctx->gradMagAvg += tlen / 2;
             }
           }
           sctx->vertNum++;

Modified: teem/trunk/src/seek/seek.h
===================================================================
--- teem/trunk/src/seek/seek.h	2023-07-22 04:00:51 UTC (rev 7138)
+++ teem/trunk/src/seek/seek.h	2023-07-22 05:08:53 UTC (rev 7139)
@@ -185,9 +185,9 @@
                                             vertex strength seen (from probing slabs) */
   double time;                           /* time for extraction */
   double gradMagAvg; /* in case per-vertex gradients were computed (such as:
-                        isocontouring without a gageContext), then the average gradient
-                        magnitude over all the verts (useful for some computations
-                        involving signed distance functions) */
+                        isocontouring without a gageContext but with normalsFind on),
+                        then the average gradient magnitude over all the verts (useful
+                        for some computations involving signed distance functions) */
 } seekContext;
 
 /* enumsSeek.c */

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