RigidBodies: Clarify usage of the custom density in the calculate mass

operator

This is only used when the preset is set to 'Custom', make that clear in
the tooltip and disable editing the value if another preset is used.

Issue came up in T88155.

Maniphest Tasks: T88155

Differential Revision: https://developer.blender.org/D11210

1 files changed, 22 insertions, 1 deletions

diff --git a/source/blender/editors/physics/rigidbody_object.c b/source/blender/editors/physics/rigidbody_object.c
index 81a8b57776b..fca3b5817b0 100644
--- a/source/blender/editors/physics/rigidbody_object.c
+++ b/source/blender/editors/physics/rigidbody_object.c
@@ -520,6 +520,26 @@ static int rigidbody_objects_calc_mass_exec(bContext *C, wmOperator *op)
   return OPERATOR_CANCELLED;
 }
 
+static bool mass_calculate_poll_property(const bContext *UNUSED(C),
+                                         wmOperator *op,
+                                         const PropertyRNA *prop)
+{
+  const char *prop_id = RNA_property_identifier(prop);
+
+  /* Disable density input when not using the 'Custom' preset. */
+  if (STREQ(prop_id, "density")) {
+    int material = RNA_enum_get(op->ptr, "material");
+    if (material >= 0) {
+      RNA_def_property_clear_flag((PropertyRNA *)prop, PROP_EDITABLE);
+    }
+    else {
+      RNA_def_property_flag((PropertyRNA *)prop, PROP_EDITABLE);
+    }
+  }
+
+  return true;
+}
+
 void RIGIDBODY_OT_mass_calculate(wmOperatorType *ot)
 {
   PropertyRNA *prop;
@@ -533,6 +553,7 @@ void RIGIDBODY_OT_mass_calculate(wmOperatorType *ot)
   ot->invoke = WM_menu_invoke; /* XXX */
   ot->exec = rigidbody_objects_calc_mass_exec;
   ot->poll = ED_operator_rigidbody_active_poll;
+  ot->poll_property = mass_calculate_poll_property;
 
   /* flags */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
@@ -554,7 +575,7 @@ void RIGIDBODY_OT_mass_calculate(wmOperatorType *ot)
                 FLT_MIN,
                 FLT_MAX,
                 "Density",
-                "Custom density value (kg/m^3) to use instead of material preset",
+                "Density value (kg/m^3), allows custom value if the 'Custom' preset is used",
                 1.0f,
                 2500.0f);
 }