DataLoaders 3: add 3D point cloud DataLoader (.ply) (#4519)

`.ply` support, but point clouds only, at least for now.

No feature flag: I had some, and tbh it only made thing needlessly hard
to work with for very little gains.
`.ply` are so common anyway, they always come up in user requests.

Here's an example from
[there](https://github.com/HuangCongQing/Point-Clouds-Visualization/blob/master/2open3D/data/fragment.ply):

![image](https://github.com/rerun-io/rerun/assets/2910679/8242c5a2-037d-46c6-9816-ab9b240a7473)


Checks:
- [x] `cargo r -p rerun-cli --no-default-features --features
native_viewer --
examples/assets/example.{glb,gltf,obj,jpg,png,rrd,txt,md,ply}`
- [x] Native: `File > Open > examples/assets/*`
- [x] Native: `Drag-n-drop > examples/assets/*`
- [x] Web: `File > Open > examples/assets/*`
- [x] Web: `Drag-n-drop > examples/assets/*`

---

Part of a series of PRs to make it possible to load _any_ file from the
local filesystem, by any means, on web and native:
- #4516
- #4517 
- #4518 
- #4519 
- #4520 
- #4521 
- TODO: register custom loaders
- TODO: high level docs and guides for everything related to loading
files

Cargo.toml

@@ -146,6 +146,7 @@ itertools = "0.11"                                                 # updating it
 js-sys = "0.3"
 # No lazy_static - use `std::sync::OnceLock` or `once_cell` instead
 libc = "0.2"
+linked-hash-map = { version = "0.5", default-features = false }
 log = "0.4"
 log-once = "0.4"
 lz4_flex = "0.11"
@@ -167,6 +168,7 @@ ordered-float = "4.2"
 parking_lot = "0.12"
 pathdiff = "0.2"
 pico-args = "0.5"
+ply-rs = { version = "0.1", default-features = false }
 polars-core = "0.29"
 polars-lazy = "0.29"
 polars-ops = "0.29"

crates/re_data_source/src/data_loader/loader_archetype.rs

@@ -80,22 +80,25 @@ impl DataLoader for ArchetypeLoader {
 
         let mut rows = Vec::new();
 
-        if crate::SUPPORTED_MESH_EXTENSIONS.contains(&extension.as_str()) {
-            re_log::debug!(?filepath, loader = self.name(), "Loading 3D model…",);
-            rows.extend(load_mesh(
-                filepath,
+        if crate::SUPPORTED_IMAGE_EXTENSIONS.contains(&extension.as_str()) {
+            re_log::debug!(?filepath, loader = self.name(), "Loading image…",);
+            rows.extend(load_image(
+                &filepath,
                 timepoint,
                 entity_path,
                 contents.into_owned(),
             )?);
-        } else if crate::SUPPORTED_IMAGE_EXTENSIONS.contains(&extension.as_str()) {
-            re_log::debug!(?filepath, loader = self.name(), "Loading image…",);
-            rows.extend(load_image(
-                &filepath,
+        } else if crate::SUPPORTED_MESH_EXTENSIONS.contains(&extension.as_str()) {
+            re_log::debug!(?filepath, loader = self.name(), "Loading 3D model…",);
+            rows.extend(load_mesh(
+                filepath,
                 timepoint,
                 entity_path,
                 contents.into_owned(),
             )?);
+        } else if crate::SUPPORTED_POINT_CLOUD_EXTENSIONS.contains(&extension.as_str()) {
+            re_log::debug!(?filepath, loader = self.name(), "Loading 3D point cloud…",);
+            rows.extend(load_point_cloud(timepoint, entity_path, &contents)?);
         } else if crate::SUPPORTED_TEXT_EXTENSIONS.contains(&extension.as_str()) {
             re_log::debug!(?filepath, loader = self.name(), "Loading text document…",);
             rows.extend(load_text_document(
@@ -118,6 +121,28 @@ impl DataLoader for ArchetypeLoader {
 
 // ---
 
+fn load_image(
+    filepath: &std::path::Path,
+    timepoint: TimePoint,
+    entity_path: EntityPath,
+    contents: Vec<u8>,
+) -> Result<impl ExactSizeIterator<Item = DataRow>, DataLoaderError> {
+    re_tracing::profile_function!();
+
+    let rows = [
+        {
+            let arch = re_types::archetypes::Image::from_file_contents(
+                contents,
+                image::ImageFormat::from_path(filepath).ok(),
+            )?;
+            DataRow::from_archetype(RowId::new(), timepoint, entity_path, &arch)?
+        },
+        //
+    ];
+
+    Ok(rows.into_iter())
+}
+
 fn load_mesh(
     filepath: std::path::PathBuf,
     timepoint: TimePoint,
@@ -140,21 +165,18 @@ fn load_mesh(
     Ok(rows.into_iter())
 }
 
-fn load_image(
-    filepath: &std::path::Path,
+fn load_point_cloud(
     timepoint: TimePoint,
     entity_path: EntityPath,
-    contents: Vec<u8>,
+    contents: &[u8],
 ) -> Result<impl ExactSizeIterator<Item = DataRow>, DataLoaderError> {
     re_tracing::profile_function!();
 
     let rows = [
         {
-            let arch = re_types::archetypes::Image::from_file_contents(
-                contents,
-                image::ImageFormat::from_path(filepath).ok(),
-            )?;
-            DataRow::from_archetype(RowId::new(), timepoint, entity_path, &arch)?
+            // TODO(#4532): `.ply` data loader should support 2D point cloud & meshes
+            let points3d = re_types::archetypes::Points3D::from_file_contents(contents)?;
+            DataRow::from_archetype(RowId::new(), timepoint, entity_path, &points3d)?
         },
         //
     ];

crates/re_data_source/src/lib.rs

@@ -45,6 +45,9 @@ pub const SUPPORTED_IMAGE_EXTENSIONS: &[&str] = &[
 
 pub const SUPPORTED_MESH_EXTENSIONS: &[&str] = &["glb", "gltf", "obj"];
 
+// TODO(#4532): `.ply` data loader should support 2D point cloud & meshes
+pub const SUPPORTED_POINT_CLOUD_EXTENSIONS: &[&str] = &["ply"];
+
 pub const SUPPORTED_RERUN_EXTENSIONS: &[&str] = &["rrd"];
 
 // TODO(#4555): Add catch-all builtin `DataLoader` for text files
@@ -64,6 +67,7 @@ pub fn supported_extensions() -> impl Iterator<Item = &'static str> {
 pub fn is_supported_file_extension(extension: &str) -> bool {
     SUPPORTED_IMAGE_EXTENSIONS.contains(&extension)
         || SUPPORTED_MESH_EXTENSIONS.contains(&extension)
+        || SUPPORTED_POINT_CLOUD_EXTENSIONS.contains(&extension)
         || SUPPORTED_RERUN_EXTENSIONS.contains(&extension)
         || SUPPORTED_TEXT_EXTENSIONS.contains(&extension)
 }

crates/re_types/Cargo.toml

@@ -62,12 +62,14 @@ arrow2 = { workspace = true, features = [
 ] }
 bytemuck = { workspace = true, features = ["derive", "extern_crate_alloc"] }
 document-features.workspace = true
+half = { workspace = true, features = ["bytemuck"] }
 infer.workspace = true
 itertools.workspace = true
-half = { workspace = true, features = ["bytemuck"] }
+linked-hash-map.workspace = true
 mime_guess2.workspace = true
 ndarray.workspace = true
 once_cell.workspace = true
+ply-rs.workspace = true
 smallvec.workspace = true
 thiserror.workspace = true
 uuid = { workspace = true, features = ["serde", "v4", "js"] }
@@ -100,8 +102,6 @@ re_types_builder.workspace = true
 rayon.workspace = true
 
 # `machete` is not a fan of `build-dependencies`.
-
-
 [package.metadata.cargo-machete]
 ignored = ["rayon", "re_build_tools", "re_types_builder"]