Fix: UI: Transform Feedback for Invalid Trackball

Patch #132957 added helpful UI feedback when attempting to rotate or
scale an object whose transforms are set to "only affect locations."
But it neglected to check for invalid trackpad rotations that are
affected the same way. This patch renames the original `HLP_ERROR` to
`HLP_ERROR_DASH` to distinguish it from a `HLP_ERROR` transform cursor
with no dashed line present, which matches trackball's normal state.

Pull Request: https://projects.blender.org/blender/blender/pulls/134653

source/blender/editors/transform/transform.hh

@@ -257,6 +257,7 @@ enum eTHelpline {
   HLP_CARROW = 5,
   HLP_TRACKBALL = 6,
   HLP_ERROR = 7,
+  HLP_ERROR_DASH = 8,
 };
 
 enum eTOType {
@@ -959,6 +960,7 @@ enum MouseInputMode {
   INPUT_CUSTOM_RATIO,
   INPUT_CUSTOM_RATIO_FLIP,
   INPUT_ERROR,
+  INPUT_ERROR_DASH,
 };
 
 void initMouseInput(TransInfo *t,

source/blender/editors/transform/transform_draw_cursors.cc

@@ -128,7 +128,7 @@ void transform_draw_cursor_draw(bContext *C, int x, int y, void *customdata)
       immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
   /* Dashed lines first. */
-  if (ELEM(t->helpline, HLP_SPRING, HLP_ANGLE, HLP_ERROR)) {
+  if (ELEM(t->helpline, HLP_SPRING, HLP_ANGLE, HLP_ERROR_DASH)) {
     GPU_line_width(DASH_WIDTH);
     immBindBuiltinProgram(GPU_SHADER_3D_LINE_DASHED_UNIFORM_COLOR);
     immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
@@ -250,6 +250,7 @@ void transform_draw_cursor_draw(bContext *C, int x, int y, void *customdata)
       break;
     }
     case HLP_ERROR:
+    case HLP_ERROR_DASH:
     case HLP_NONE:
       break;
   }

source/blender/editors/transform/transform_input.cc

@@ -430,6 +430,10 @@ void initMouseInputMode(TransInfo *t, MouseInput *mi, MouseInputMode mode)
       mi->apply = nullptr;
       t->helpline = HLP_ERROR;
       break;
+    case INPUT_ERROR_DASH:
+      mi->apply = nullptr;
+      t->helpline = HLP_ERROR_DASH;
+      break;
     case INPUT_NONE:
     default:
       mi->apply = nullptr;
@@ -472,6 +476,7 @@ void initMouseInputMode(TransInfo *t, MouseInput *mi, MouseInputMode mode)
       }
       break;
     case HLP_ERROR:
+    case HLP_ERROR_DASH:
       t->flag |= T_MODAL_CURSOR_SET;
       WM_cursor_modal_set(win, WM_CURSOR_STOP);
       break;

source/blender/editors/transform/transform_mode.cc

@@ -79,6 +79,13 @@ bool transform_mode_is_changeable(const int mode)
               TFM_NORMAL_ROTATION);
 }
 
+bool transform_mode_affect_only_locations(const TransInfo *t)
+{
+  return (t->flag & T_V3D_ALIGN) && (t->options & CTX_OBJECT) &&
+         (t->settings->transform_pivot_point != V3D_AROUND_CURSOR) && t->context &&
+         (CTX_DATA_COUNT(t->context, selected_editable_objects) == 1);
+}
+
 /* -------------------------------------------------------------------- */
 /** \name Transform Locks
  * \{ */

source/blender/editors/transform/transform_mode.hh

@@ -68,6 +68,7 @@ bool transdata_check_local_center(const TransInfo *t, short around);
  * Informs if the mode can be switched during modal.
  */
 bool transform_mode_is_changeable(int mode);
+bool transform_mode_affect_only_locations(const TransInfo *t);
 void protectedTransBits(short protectflag, float vec[3]);
 void protectedSizeBits(short protectflag, float size[3]);
 void constraintTransLim(const TransInfo *t, const TransDataContainer *tc, TransData *td);

source/blender/editors/transform/transform_mode_resize.cc

@@ -312,17 +312,14 @@ static void initResize(TransInfo *t, wmOperator *op)
     zero_v3(mouse_dir_constraint);
   }
 
-  const bool only_location = (t->flag & T_V3D_ALIGN) && (t->options & CTX_OBJECT) &&
+  const bool only_location = transform_mode_affect_only_locations(t);
-                             (t->settings->transform_pivot_point != V3D_AROUND_CURSOR) &&
-                             t->context &&
-                             (CTX_DATA_COUNT(t->context, selected_editable_objects) == 1);
   if (only_location) {
     WorkspaceStatus status(t->context);
     status.item(TIP_("Transform is set to only affect location"), ICON_ERROR);
   }
 
   if (is_zero_v3(mouse_dir_constraint)) {
-    initMouseInputMode(t, &t->mouse, only_location ? INPUT_ERROR : INPUT_SPRING_FLIP);
+    initMouseInputMode(t, &t->mouse, only_location ? INPUT_ERROR_DASH : INPUT_SPRING_FLIP);
   }
   else {
     int mval_start[2], mval_end[2];
@@ -350,7 +347,7 @@ static void initResize(TransInfo *t, wmOperator *op)
 
     setCustomPoints(t, &t->mouse, mval_end, mval_start);
 
-    initMouseInputMode(t, &t->mouse, only_location ? INPUT_ERROR : INPUT_CUSTOM_RATIO);
+    initMouseInputMode(t, &t->mouse, only_location ? INPUT_ERROR_DASH : INPUT_CUSTOM_RATIO);
   }
 
   t->num.val_flag[0] |= NUM_NULL_ONE;

source/blender/editors/transform/transform_mode_rotate.cc

@@ -411,14 +411,10 @@ static void initRotation(TransInfo *t, wmOperator * /*op*/)
 
   t->mode = TFM_ROTATION;
 
-  const bool only_location = (t->flag & T_V3D_ALIGN) && (t->options & CTX_OBJECT) &&
+  if (transform_mode_affect_only_locations(t)) {
-                             (t->settings->transform_pivot_point != V3D_AROUND_CURSOR) &&
-                             t->context &&
-                             (CTX_DATA_COUNT(t->context, selected_editable_objects) == 1);
-  if (only_location) {
     WorkspaceStatus status(t->context);
     status.item(TIP_("Transform is set to only affect location"), ICON_ERROR);
-    initMouseInputMode(t, &t->mouse, INPUT_ERROR);
+    initMouseInputMode(t, &t->mouse, INPUT_ERROR_DASH);
   }
   else {
     initMouseInputMode(t, &t->mouse, INPUT_ANGLE);

source/blender/editors/transform/transform_mode_trackball.cc

@@ -191,7 +191,14 @@ static void initTrackball(TransInfo *t, wmOperator * /*op*/)
 {
   t->mode = TFM_TRACKBALL;
 
-  initMouseInputMode(t, &t->mouse, INPUT_TRACKBALL);
+  if (transform_mode_affect_only_locations(t)) {
+    WorkspaceStatus status(t->context);
+    status.item(TIP_("Transform is set to only affect location"), ICON_ERROR);
+    initMouseInputMode(t, &t->mouse, INPUT_ERROR);
+  }
+  else {
+    initMouseInputMode(t, &t->mouse, INPUT_TRACKBALL);
+  }
 
   t->idx_max = 1;
   t->num.idx_max = 1;

source/blender/editors/transform/transform_ops.cc

@@ -420,7 +420,7 @@ static int transform_modal(bContext *C, wmOperator *op, const wmEvent *event)
   /* XXX insert keys are called here, and require context. */
   t->context = C;
 
-  if ((t->helpline != HLP_ERROR)) {
+  if (t->helpline != HLP_ERROR && t->helpline != HLP_ERROR_DASH) {
     ED_workspace_status_text(t->context, nullptr);
   }