GPencil: Improve smooth operation

This patch makes the grease pencil smooth operation symmetric.
It also increases the performance a lot if strong smoothing is
required. Additionally there is an option for the position smooth
operation to keep the shape closer to the original for more iterations.

Since the result differs from the previous algorithm, versioning is used
to change the iterations and factor to match the old result.

Differential Revision: http://developer.blender.org/D14325

1 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/blenloader/intern/versioning_300.c b/source/blender/blenloader/intern/versioning_300.c
index 51b5cab1f7c..adc6b990869 100644
--- a/source/blender/blenloader/intern/versioning_300.c
+++ b/source/blender/blenloader/intern/versioning_300.c
@@ -2415,6 +2415,24 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
         }
       }
     }
+
+    /* Change grease pencil smooth iterations to match old results with new algorithm. */
+    LISTBASE_FOREACH (Object *, ob, &bmain->objects) {
+      LISTBASE_FOREACH (GpencilModifierData *, md, &ob->greasepencil_modifiers) {
+        if (md->type == eGpencilModifierType_Smooth) {
+          SmoothGpencilModifierData *gpmd = (SmoothGpencilModifierData *)md;
+          if (gpmd->step == 1 && gpmd->factor <= 0.5f) {
+            gpmd->factor *= 2.0f;
+          }
+          else {
+            gpmd->step = 1 + (int)(gpmd->factor * max_ff(0.0f,
+                                                         min_ff(5.1f * sqrtf(gpmd->step) - 3.0f,
+                                                                gpmd->step + 2.0f)));
+            gpmd->factor = 1.0f;
+          }
+        }
+      }
+    }
   }
 
   /**