Point clouds: drawn from their scans, placed, cropped and attached as the reference does

Scans (.rcs) and projects (.rcp) are read and their points drawn as
screen-sized dots, coloured by the cloud's stylization. The cloud's
placement carries its scale and rotation; its extents and crops stay in
the scan's coordinates. A missing scan shows the extents with the saved
path. -POINTCLOUDATTACH / POINTCLOUDATTACH, POINTCLOUDCROP and the
POINTCLOUD* settings follow the reference's prompts and messages, the
Properties list is the reference's, and a locked cloud is left alone by
edits.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/io/xref.rs

@@ -322,6 +322,21 @@ pub fn register_underlay_sources(doc: &CadDocument, base_dir: &Path) {
             crate::scene::model::pdf_raster::register_source(stored, std::sync::Arc::new(bytes));
         }
     }
+    // Point cloud scans are large and read lazily: register where they are.
+    for object in doc.objects.values() {
+        let codec::objects::ObjectType::ClassObject(object) = object else {
+            continue;
+        };
+        let (codec::objects::ClassObjectData::PointCloudDefinitionEx(def)
+        | codec::objects::ClassObjectData::PointCloudDefinition(def)) = &object.data
+        else {
+            continue;
+        };
+        let stored = def.source_filename.trim();
+        if let Some(found) = (!stored.is_empty()).then(|| resolve_path(stored, base_dir)).flatten() {
+            crate::scene::model::point_cloud::register_source(stored, found);
+        }
+    }
 }
 
 /// Layer properties an override can change, as compared for the
@@ -3106,3 +3121,24 @@ mod tests {
         }
     }
 }
+
+/// Point cloud definitions keep the full path while the drawing is open; a
+/// DWG stores it relative to the drawing (".\rcs\scan.rcs"), as the
+/// reference writes it. Paths on another drive stay full.
+pub fn relative_point_cloud_paths(doc: &mut CadDocument, host: &Path) {
+    use crate::io::xref_model::{is_relative_path, normalize_lexical, to_pathtype_result, Pathtype};
+    for object in doc.objects.values_mut() {
+        let codec::objects::ObjectType::ClassObject(object) = object else {
+            continue;
+        };
+        let codec::objects::ClassObjectData::PointCloudDefinitionEx(def) = &mut object.data else {
+            continue;
+        };
+        if def.source_filename.is_empty() || is_relative_path(&normalize_lexical(&def.source_filename)) {
+            continue;
+        }
+        if let Ok(relative) = to_pathtype_result(&def.source_filename, host, Pathtype::Relative) {
+            def.source_filename = relative.replace('/', "\\");
+        }
+    }
+}