REFINE_LOOP: minor improvement

diff --git a/s2tc_compressor.cpp b/s2tc_compressor.cpp
index 35c5449..5504b1d 100644 (file)
--- a/s2tc_compressor.cpp
+++ b/s2tc_compressor.cpp
@@ -750,17 +750,35 @@ namespace
                                                                }
                                                        }
                                                        int bitindex = pindex * 2;
-                                                       if(testbit(&out[(dxt == DXT1 ? 4 : 12)], bitindex))
+                                                       if(refine == REFINE_CHECK)
                                                        {
-                                                               // we picked an 1
-                                                               score_01 += ColorDist(c[1], c[4]);
-                                                               score_23 += ColorDist(c[3], c[4]);
+                                                               if(testbit(&out[(dxt == DXT1 ? 4 : 12)], bitindex))
+                                                               {
+                                                                       // we picked an 1
+                                                                       score_01 += ColorDist(c[1], c[4]);
+                                                                       score_23 += ColorDist(c[3], c[4]);
+                                                               }
+                                                               else
+                                                               {
+                                                                       // we picked a 0
+                                                                       score_01 += ColorDist(c[0], c[4]);
+                                                                       score_23 += ColorDist(c[2], c[4]);
+                                                               }
                                                        }
-                                                       else
+                                                       else if(refine == REFINE_LOOP)
                                                        {
-                                                               // we picked a 0
-                                                               score_01 += ColorDist(c[0], c[4]);
-                                                               score_23 += ColorDist(c[2], c[4]);
+                                                               if(testbit(&out[(dxt == DXT1 ? 4 : 12)], bitindex))
+                                                               {
+                                                                       // we picked an 1
+                                                                       score_23 += ColorDist(c[3], c[4]);
+                                                               }
+                                                               else
+                                                               {
+                                                                       // we picked a 0
+                                                                       score_23 += ColorDist(c[2], c[4]);
+                                                               }
+                                                               // we WILL run another loop iteration, if score_01 wins
+                                                               score_01 += min(ColorDist(c[0], c[4]), ColorDist(c[1], c[4]));
                                                        }
                                                }
 
@@ -775,6 +793,11 @@ namespace
 
                                        // alpha refinement is always good and doesn't
                                        // need to be checked because alpha is linear
+
+                                       // when looping, though, checking the
+                                       // alpha COULD help, but we usually
+                                       // loop twice anyway as refinement
+                                       // usually helps
                                }
                        }
                }