Fix T99342: GPencil multiframe falloff is scaling wrongly in rotation

The falloff was applied to scale by error. Now, the falloff is only applied to the rotation.

Differential Revision: https://developer.blender.org/D15364

.

1 files changed, 6 insertions, 10 deletions

diff --git a/source/blender/editors/transform/transform_mode.c b/source/blender/editors/transform/transform_mode.c
index 2fd81486bb6..8df0f4eabd1 100644
--- a/source/blender/editors/transform/transform_mode.c
+++ b/source/blender/editors/transform/transform_mode.c
@@ -549,18 +549,14 @@ void ElementRotation_ex(const TransInfo *t,
     mul_m3_m3m3(totmat, mat, td->mtx);
     mul_m3_m3m3(smat, td->smtx, totmat);
 
-    /* apply gpencil falloff */
+    /* Apply gpencil falloff. */
     if (t->options & CTX_GPENCIL_STROKES) {
       bGPDstroke *gps = (bGPDstroke *)td->extra;
-      float sx = smat[0][0];
-      float sy = smat[1][1];
-      float sz = smat[2][2];
-
-      mul_m3_fl(smat, gps->runtime.multi_frame_falloff);
-      /* fix scale */
-      smat[0][0] = sx;
-      smat[1][1] = sy;
-      smat[2][2] = sz;
+      if (gps->runtime.multi_frame_falloff != 1.0f) {
+        float ident_mat[3][3];
+        unit_m3(ident_mat);
+        interp_m3_m3m3(smat, ident_mat, smat, gps->runtime.multi_frame_falloff);
+      }
     }
 
     sub_v3_v3v3(vec, td->iloc, center);