IMPORT: 3D Studio files

A .3ds file opens the 3D Studio Import window: the file's objects with
their kind and material count, filtered by kind or name, checked one by
one or all at once, where to put them on layers and what a mesh with
several materials becomes. Checked meshes come in as polyface meshes on
the chosen layers with materials made from the file's colours, cameras
as named views; a mesh with several materials is split, given its first
material, given none, or asked about on the command line. Automation
drives the window with tds_import_dialog.

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

src/app/view/modal.rs

@@ -51,6 +51,7 @@ impl OpenCADStudio {
             Some(K::PdfImportFile) => crate::t!("Import PDF").into_owned(),
             Some(K::ImportFile) => crate::t!("Import File").into_owned(),
             Some(K::DgnImport) => crate::t!("DGN Import").into_owned(),
+            Some(K::TdsImport) => crate::tr!("import-3ds", "title"),
             Some(K::XrefAttach) => crate::t!("Attach External Reference").into_owned(),
             Some(K::WriteBlock) => crate::t!("Write Block").into_owned(),
             Some(K::GeometricTolerance) => crate::t!("Geometric Tolerance").into_owned(),
@@ -613,6 +614,12 @@ impl OpenCADStudio {
                     crate::ui::window::import_dialogs::view_import_file(state, recent, flow)
                 })
             }
+            super::super::ModalKind::TdsImport => {
+                let state = self.import_dialogs.tds.as_ref()?;
+                sized_flow(ex, 860, 560, |flow| {
+                    crate::ui::window::import_dialogs::view_tds_import(state, flow)
+                })
+            }
             super::super::ModalKind::DgnImport => {
                 let state = self.import_dialogs.dgn.as_ref()?;
                 sized_flow(ex, 900, 680, |flow| {