Merge branch 'blender-v2.82-release'

4 files changed, 37 insertions, 9 deletions

diff --git a/source/blender/editors/space_image/image_ops.c b/source/blender/editors/space_image/image_ops.c
index 2ed8b8c87ff..17c6f76a1d9 100644
--- a/source/blender/editors/space_image/image_ops.c
+++ b/source/blender/editors/space_image/image_ops.c
@@ -3356,6 +3356,9 @@ static void image_sample_draw(const bContext *C, ARegion *ar, void *arg_info)
 /* Returns color in linear space, matching ED_space_node_color_sample(). */
 bool ED_space_image_color_sample(SpaceImage *sima, ARegion *ar, int mval[2], float r_col[3])
 {
+  if (sima->image == NULL) {
+    return false;
+  }
   float uv[2];
   UI_view2d_region_to_view(&ar->v2d, mval[0], mval[1], &uv[0], &uv[1]);
   int tile = BKE_image_get_tile_from_pos(sima->image, uv, uv, NULL);
diff --git a/source/blender/editors/space_view3d/view3d_edit.c b/source/blender/editors/space_view3d/view3d_edit.c
index 3dcde401216..a4714249da2 100644
--- a/source/blender/editors/space_view3d/view3d_edit.c
+++ b/source/blender/editors/space_view3d/view3d_edit.c
@@ -758,7 +758,32 @@ static void viewrotate_apply(ViewOpsData *vod, const int event_xy[2])
     quat_to_mat3(m, vod->curr.viewquat);
     invert_m3_m3(m_inv, m);
 
-    /* avoid gimble lock */
+    /* Avoid Gimble Lock
+     *
+     * Even though turn-table mode is in use, this can occur when the user exits the camera view
+     * or when aligning the view to a rotated object.
+     *
+     * We have gimble lock when the user's view is rotated +/- 90 degrees along the view axis.
+     * In this case the vertical rotation is the same as the sideways turntable motion.
+     * Making it impossible to get out of the gimble locked state without resetting the view.
+     *
+     * The logic below lets the user exit out of this state without any abrupt 'fix'
+     * which would be disorienting.
+     *
+     * This works by blending two horizons:
+     * - Rotated-horizon: `cross_v3_v3v3(xaxis, zvec_global, m_inv[2])`
+     *   When only this is used, this turntable rotation works - but it's side-ways
+     *   (as if the entire turn-table has been placed on it's side)
+     *   While there is no gimble lock, it's also awkward to use.
+     * - Un-rotated-horizon: `m_inv[0]`
+     *   When only this is used, the turntable rotation can have gimbal lock.
+     *
+     * The solution used here is to blend between these two values,
+     * so the severity of the gimbal lock is used to blend the rotated horizon.
+     * Blending isn't essential, it just makes the transition smoother.
+     *
+     * This allows sideways turn-table rotation on a Z axis that isn't world-space Z,
+     * While up-down turntable rotation eventually corrects gimble lock. */
 #if 1
     if (len_squared_v3v3(zvec_global, m_inv[2]) > 0.001f) {
       float fac;
diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index a83a36fbd9d..db2be4c551d 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -2671,14 +2671,14 @@ static void rna_def_object(BlenderRNA *brna)
   prop = RNA_def_property(srna, "lock_location", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_LOCX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Location", "Lock editing of location in the interface");
+  RNA_def_property_ui_text(prop, "Lock Location", "Lock editing of location when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_update(prop, NC_OBJECT | ND_TRANSFORM, "rna_Object_internal_update");
 
   prop = RNA_def_property(srna, "lock_rotation", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_ROTX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Rotation", "Lock editing of rotation in the interface");
+  RNA_def_property_ui_text(prop, "Lock Rotation", "Lock editing of rotation when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_update(prop, NC_OBJECT | ND_TRANSFORM, "rna_Object_internal_update");
 
@@ -2690,7 +2690,7 @@ static void rna_def_object(BlenderRNA *brna)
   RNA_def_property_ui_text(
       prop,
       "Lock Rotation (4D Angle)",
-      "Lock editing of 'angle' component of four-component rotations in the interface");
+      "Lock editing of 'angle' component of four-component rotations when transforming");
   /* XXX this needs a better name */
   prop = RNA_def_property(srna, "lock_rotations_4d", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_ROT4D);
@@ -2702,7 +2702,7 @@ static void rna_def_object(BlenderRNA *brna)
   prop = RNA_def_property(srna, "lock_scale", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_SCALEX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Scale", "Lock editing of scale in the interface");
+  RNA_def_property_ui_text(prop, "Lock Scale", "Lock editing of scale when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_update(prop, NC_OBJECT | ND_TRANSFORM, "rna_Object_internal_update");
 
diff --git a/source/blender/makesrna/intern/rna_pose.c b/source/blender/makesrna/intern/rna_pose.c
index 43d0402d00a..85c4352d277 100644
--- a/source/blender/makesrna/intern/rna_pose.c
+++ b/source/blender/makesrna/intern/rna_pose.c
@@ -1356,7 +1356,7 @@ static void rna_def_pose_channel(BlenderRNA *brna)
   prop = RNA_def_property(srna, "lock_location", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_LOCX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Location", "Lock editing of location in the interface");
+  RNA_def_property_ui_text(prop, "Lock Location", "Lock editing of location when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
   RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
@@ -1364,7 +1364,7 @@ static void rna_def_pose_channel(BlenderRNA *brna)
   prop = RNA_def_property(srna, "lock_rotation", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_ROTX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Rotation", "Lock editing of rotation in the interface");
+  RNA_def_property_ui_text(prop, "Lock Rotation", "Lock editing of rotation when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
   RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
@@ -1376,7 +1376,7 @@ static void rna_def_pose_channel(BlenderRNA *brna)
   RNA_def_property_ui_text(
       prop,
       "Lock Rotation (4D Angle)",
-      "Lock editing of 'angle' component of four-component rotations in the interface");
+      "Lock editing of 'angle' component of four-component rotations when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
   RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
@@ -1394,7 +1394,7 @@ static void rna_def_pose_channel(BlenderRNA *brna)
   prop = RNA_def_property(srna, "lock_scale", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "protectflag", OB_LOCK_SCALEX);
   RNA_def_property_array(prop, 3);
-  RNA_def_property_ui_text(prop, "Lock Scale", "Lock editing of scale in the interface");
+  RNA_def_property_ui_text(prop, "Lock Scale", "Lock editing of scale when transforming");
   RNA_def_property_ui_icon(prop, ICON_UNLOCKED, 1);
   RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
   RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");