Sculpt: Add orientation modes to the Cloth Filter

This adds the orientation modes to the Cloth Filter.
Similar to the mesh filter, they set the orientation of the axis when
limiting the forces.

When using the gravity mesh filter, the orientation also sets the gravity
direction. In world orientation, cloth will always fall towards the
ground plane. In view mode, cloth will always fall down relative to the
view.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8618

1 files changed, 39 insertions, 1 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_cloth.c b/source/blender/editors/sculpt_paint/sculpt_cloth.c
index 9a3fbe474b8..cf2ed0943eb 100644
--- a/source/blender/editors/sculpt_paint/sculpt_cloth.c
+++ b/source/blender/editors/sculpt_paint/sculpt_cloth.c
@@ -1071,6 +1071,25 @@ static EnumPropertyItem prop_cloth_filter_type[] = {
     {0, NULL, 0, NULL, NULL},
 };
 
+static EnumPropertyItem prop_cloth_filter_orientation_items[] = {
+    {SCULPT_FILTER_ORIENTATION_LOCAL,
+     "LOCAL",
+     0,
+     "Local",
+     "Use the local axis to limit the force and set the gravity direction"},
+    {SCULPT_FILTER_ORIENTATION_WORLD,
+     "WORLD",
+     0,
+     "World",
+     "Use the global axis to limit the force and set the gravity direction"},
+    {SCULPT_FILTER_ORIENTATION_VIEW,
+     "VIEW",
+     0,
+     "View",
+     "Use the view axis to limit the force and set the gravity direction"},
+    {0, NULL, 0, NULL, NULL},
+};
+
 typedef enum eClothFilterForceAxis {
   CLOTH_FILTER_FORCE_X = 1 << 0,
   CLOTH_FILTER_FORCE_Y = 1 << 1,
@@ -1120,7 +1139,15 @@ static void cloth_filter_apply_forces_task_cb(void *__restrict userdata,
 
     switch (filter_type) {
       case CLOTH_FILTER_GRAVITY:
-        force[2] = -data->filter_strength * fade;
+        if (ss->filter_cache->orientation == SCULPT_FILTER_ORIENTATION_VIEW) {
+          /* When using the view orientation apply gravity in the -Y axis, this way objects will
+           * fall down instead of backwards. */
+          force[1] = -data->filter_strength * fade;
+        }
+        else {
+          force[2] = -data->filter_strength * fade;
+        }
+        SCULPT_filter_to_object_space(force, ss->filter_cache);
         break;
       case CLOTH_FILTER_INFLATE: {
         float normal[3];
@@ -1138,11 +1165,13 @@ static void cloth_filter_apply_forces_task_cb(void *__restrict userdata,
         break;
     }
 
+    SCULPT_filter_to_orientation_space(force, ss->filter_cache);
     for (int axis = 0; axis < 3; axis++) {
       if (!ss->filter_cache->enabled_force_axis[axis]) {
         force[axis] = 0.0f;
       }
     }
+    SCULPT_filter_to_object_space(force, ss->filter_cache);
 
     add_v3_v3(force, sculpt_gravity);
 
@@ -1264,6 +1293,9 @@ static int sculpt_cloth_filter_invoke(bContext *C, wmOperator *op, const wmEvent
   ss->filter_cache->enabled_force_axis[1] = force_axis & CLOTH_FILTER_FORCE_Y;
   ss->filter_cache->enabled_force_axis[2] = force_axis & CLOTH_FILTER_FORCE_Z;
 
+  SculptFilterOrientation orientation = RNA_enum_get(op->ptr, "orientation");
+  ss->filter_cache->orientation = orientation;
+
   WM_event_add_modal_handler(C, op);
   return OPERATOR_RUNNING_MODAL;
 }
@@ -1297,6 +1329,12 @@ void SCULPT_OT_cloth_filter(struct wmOperatorType *ot)
                     CLOTH_FILTER_FORCE_X | CLOTH_FILTER_FORCE_Y | CLOTH_FILTER_FORCE_Z,
                     "Force axis",
                     "Apply the force in the selected axis");
+  RNA_def_enum(ot->srna,
+               "orientation",
+               prop_cloth_filter_orientation_items,
+               SCULPT_FILTER_ORIENTATION_LOCAL,
+               "Orientation",
+               "Orientation of the axis to limit the filter force");
   RNA_def_float(ot->srna,
                 "cloth_mass",
                 1.0f,