1 files changed, 44 insertions, 30 deletions

diff --git a/linden/indra/llmath/llvolume.cpp b/linden/indra/llmath/llvolume.cpp
index 7f2a663..9cad612 100644
--- a/linden/indra/llmath/llvolume.cpp
+++ b/linden/indra/llmath/llvolume.cpp
@@ -1,6 +1,8 @@
 /** 
  * @file llvolume.cpp
  *
+ * $LicenseInfo:firstyear=2002&license=viewergpl$
+ * 
  * Copyright (c) 2002-2007, Linden Research, Inc.
  * 
  * Second Life Viewer Source Code
@@ -23,6 +25,7 @@
  * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
  * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
  * COMPLETENESS OR PERFORMANCE.
+ * $/LicenseInfo$
  */
 
 #include "linden_common.h"
@@ -83,6 +86,8 @@ const S32 SCULPT_REZ_2 = 8;
 const S32 SCULPT_REZ_3 = 16;
 const S32 SCULPT_REZ_4 = 32;
 
+const F32 SCULPT_MIN_AREA = 0.005f;
+
 BOOL check_same_clock_dir( const LLVector3& pt1, const LLVector3& pt2, const LLVector3& pt3, const LLVector3& norm)
 {    
         LLVector3 test = (pt2-pt1)%(pt3-pt2);
@@ -1825,6 +1830,18 @@ void LLVolume::createVolumeFaces()
 }
 
 
+inline LLVector3 sculpt_rgb_to_vector(U8 r, U8 g, U8 b)
+{
+        // maps RGB values to vector values [0..255] -> [-0.5..0.5]
+        LLVector3 value;
+        value.mV[VX] = r / 256.f - 0.5f;
+        value.mV[VY] = g / 256.f - 0.5f;
+        value.mV[VZ] = b / 256.f - 0.5f;
+
+        return value;
+}
+
+
 // sculpt replaces generate() for sculpted surfaces
 void LLVolume::sculpt(U16 sculpt_width, U16 sculpt_height, S8 sculpt_components, const U8* sculpt_data, S32 sculpt_level)
 {
@@ -1849,40 +1866,39 @@ void LLVolume::sculpt(U16 sculpt_width, U16 sculpt_height, S8 sculpt_components,
         mMesh.resize(sizeS * sizeT);
         sNumMeshPoints += mMesh.size();
 
-        S32 vertex_change = 0;
+        F32 area = 0;
         // first test to see if image has enough variation to create non-degenerate geometry
         if (!data_is_empty)
         {
-                S32 last_index = 0;
-                for (S32 s = 0; s < sizeS; s++)
-                        for (S32 t = 0; t < sizeT; t++)
+                for (S32 s = 0; s < sizeS - 1; s++)
+                        for (S32 t = 0; t < sizeT - 1; t++)
                         {
-                                U32 x = (U32) ((F32)s/(sizeS-1) * (F32) sculpt_width);
-                                U32 y = (U32) ((F32)t/(sizeT-1) * (F32) sculpt_height);
+                                // first coordinate
+                                U32 x = (U32) ((F32)s/(sizeS) * (F32) sculpt_width);
+                                U32 y = (U32) ((F32)t/(sizeT) * (F32) sculpt_height);
 
-                                if (y == sculpt_height)  // stitch bottom
-                                {
-                                        y = sculpt_height - 1;
-                                        x = sculpt_width / 2;
-                                }
-
-                                if (x == sculpt_width)   // stitch sides
-                                        x = 0;
-
-                                if (y == 0)  // stitch top
-                                        x = sculpt_width / 2;
-
-                                U32 index = (x + y * sculpt_width) * sculpt_components;
-
-                                if (fabs((F32)(sculpt_data[index] - sculpt_data[last_index])) +
-                                        fabs((F32)(sculpt_data[index+1] - sculpt_data[last_index+1])) +
-                                        fabs((F32)(sculpt_data[index+2] - sculpt_data[last_index+2])) > 0)
-                                        vertex_change++;
-
-                                last_index = index;
+                                // coordinate offset by 1
+                                U32 x2 = (U32) ((F32)(s+1)/(sizeS) * (F32) sculpt_width);
+                                U32 y2 = (U32) ((F32)(t+1)/(sizeT) * (F32) sculpt_height);
+                                        
+                                // three points on a triagle - find the image indices first
+                                U32 p1_index = (x + y * sculpt_width) * sculpt_components;
+                                U32 p2_index = (x2 + y * sculpt_width) * sculpt_components;
+                                U32 p3_index = (x + y2 * sculpt_width) * sculpt_components;
+
+                                // convert image data to vectors
+                                LLVector3 p1 = sculpt_rgb_to_vector(sculpt_data[p1_index], sculpt_data[p1_index+1], sculpt_data[p1_index+2]);
+                                LLVector3 p2 = sculpt_rgb_to_vector(sculpt_data[p2_index], sculpt_data[p2_index+1], sculpt_data[p2_index+2]);
+                                LLVector3 p3 = sculpt_rgb_to_vector(sculpt_data[p3_index], sculpt_data[p3_index+1], sculpt_data[p3_index+2]);
+
+                                // compute the area of the parallelogram by taking the length of the cross product:
+                                // (parallegram is an approximation of two triangles)
+                                LLVector3 cross = (p1 - p2) % (p1 - p3);
+                                // take length squared for efficiency (no sqrt)
+                                area += cross.magVecSquared();
                         }
                 
-                if ((F32)vertex_change / sizeS / sizeT < 0.02) // less than 2%
+                if (area < SCULPT_MIN_AREA * SCULPT_MIN_AREA)
                         data_is_empty = TRUE;
         }
 
@@ -1974,9 +1990,7 @@ void LLVolume::sculpt(U16 sculpt_width, U16 sculpt_height, S8 sculpt_components,
 
                                 
                                 U32 index = (x + y * sculpt_width) * sculpt_components;
-                                pt.mPos.mV[0] = sculpt_data[index  ] / 256.f - 0.5f;
-                                pt.mPos.mV[1] = sculpt_data[index+1] / 256.f - 0.5f;
-                                pt.mPos.mV[2] = sculpt_data[index+2] / 256.f - 0.5f;
+                                pt.mPos = sculpt_rgb_to_vector(sculpt_data[index], sculpt_data[index+1], sculpt_data[index+2]);
                         }
                         line += sizeT;
                 }