webassembly/app.html: Fetch mesh from search-query url-param

webassembly/app.html

@@ -212,8 +212,6 @@ <h1 class="title">F3D Web</h1>
             openFile(document.getElementById('file-name').innerHTML);
           });
 
-        // load the file located in the virtual filesystem
-        openFile('f3d.vtp');
 
         // setup the window size based on the canvas size
         const main = document.getElementById('main');
@@ -223,6 +221,49 @@ <h1 class="title">F3D Web</h1>
         // do a first render and start the interactor
         Module.engineInstance.getWindow().render();
         Module.engineInstance.getInteractor().start();
+
+        // Parse search-query mesh url-param or load default mesh file
+        // const params = new URLSearchParams(window.location.search);
+        // Replace first hash with question mark to have real search query parsing and avoid leading # in first parsed urlparam
+        const params = new URLSearchParams(window.location.hash.replace('#', '?'));
+        const mesh_url_passed = params.get("mesh");
+        const extension_parsed = params.get("extension");
+        if (mesh_url_passed) {
+          const mesh_url = decodeURI(mesh_url_passed);
+          fetch(mesh_url)
+          .then((response) => {
+            if (!response.ok) {
+              throw new Error(`HTTP error, status = ${response.status}`);
+            }
+            // Build filename given extension urlparam or response header content-disposition
+            let filename;
+            if (extension_parsed) {
+              filename = `mesh_urlparam.${extension_parsed}`;
+            } else {
+              // If extension is not provided by user, try to get it auto from content-disposition header of url extension 
+              const contentDisposition = response.headers.get('content-disposition');
+              if (contentDisposition) {
+                filename = contentDisposition.split('filename=')[1].split(';')[0];
+              } else {
+                try {
+                  filename = mesh_url.split('/').pop();
+                  const url_extension = '.' + mesh_url.split('.').at(-1) ;
+                } catch {
+                  throw new Error(`Could not infer file extension from content-disposition or url extension. Please enforce it via the extension urlparam`);
+                }
+              }
+            }
+            // Convert buffer to Uint8Array and openFile
+            response.arrayBuffer().then((buffer) => {
+              const uint8array = new Uint8Array(buffer);
+              Module.FS.writeFile(filename, uint8array);
+              openFile(filename);
+            });
+          })
+        } else {
+          // load the file located in the virtual filesystem
+          openFile('f3d.vtp');
+        }
       })
       .catch(error => console.error("Internal exception: " + error));
   </script>