refactor: change mesh load pipeline

These changes allow mesh loading to conform even better to the file format, meaning that loading should be more natural and performant.

src/assets/asset_manager.rs

@@ -1,5 +1,3 @@
-use crate::assets::loaders::mat_loader::MaterialLoader;
-use crate::assets::loaders::mesh_loader::MeshLoader;
 use crate::common::material::{Material, MaterialRegistry};
 use crate::common::mesh::{MeshHandle, MeshRegistry};
 use crate::common::scene::Scene;
@@ -11,6 +9,7 @@ use std::path::Path;
 use std::sync::Arc;
 use vulkano::buffer::Subbuffer;
 use vulkano::memory::allocator::MemoryAllocator;
+use crate::assets::loaders::model_loader::{ModelLoadOptions, ModelLoader};
 
 /// A manager that controls all assets used for display. It handles loading all meshes, materials,
 /// and textures for now.
@@ -27,10 +26,6 @@ pub struct AssetManager {
     material_registry: MaterialRegistry,
     /// The asset manager's [`TextureRegistry`].
     texture_registry: TextureRegistry,
-
-    // Loaders
-    mesh_loader: MeshLoader,
-    material_loader: MaterialLoader,
 }
 
 impl AssetManager {
@@ -43,8 +38,6 @@ impl AssetManager {
             mesh_registry,
             material_registry,
             texture_registry: TextureRegistry::new(),
-            mesh_loader: MeshLoader::new(),
-            material_loader: MaterialLoader::new(),
         }
     }
 
@@ -59,8 +52,12 @@ impl AssetManager {
         // `MeshRegistry::append_mesh`), matching the index materials are registered under below.
         // Not every mesh format has a material loader yet (e.g. `.obj`), so a failure here just
         // means no materials get registered for this mesh rather than failing the whole load.
-        match self.material_loader.load_materials(&path) {
-            Ok(materials) => {
+        let path = path.as_ref();
+        let mut loader = ModelLoader::new();
+        let model_info = loader.load_model(path, ModelLoadOptions::default())?;
+        
+        match model_info.materials {
+            Some(materials) => {
                 for (index, info) in materials.into_iter().enumerate() {
                     let material_id = format!("{mesh_id}_mat_{index}");
                     self.material_registry
@@ -68,10 +65,11 @@ impl AssetManager {
                     println!("Loaded material {material_id}");
                 }
             }
-            Err(err) => println!("No materials loaded for mesh \"{mesh_id}\": {err}"),
+            None => println!("No materials loaded for mesh \"{mesh_id}\""),
         }
 
-        let mesh = self.mesh_loader.load_mesh(&path)?;
+        let mesh = model_info.mesh
+            .expect("Mesh was not loaded");
         self.mesh_registry.register_mesh(mesh_id.clone(), mesh);
 
         Ok(())

src/assets/loaders/gltf_loader.rs

@@ -1,19 +1,73 @@
 use anyhow::Result;
 use std::path::Path;
-use gltf::buffer::Data;
+use gltf::buffer::Data as BufferData;
+use gltf::image::Data as ImageData;
 use gltf::image::Source;
-use gltf::Texture;
+use gltf::{Document, Texture};
 use nalgebra::{Matrix4, Vector4};
 use crate::assets::loaders::common::{MaterialLoadInfo, MaterialUniforms, MeshLoadInfo, Submesh, TextureLoadInfo};
+use crate::assets::loaders::model_loader::{LoadModel, ModelLoadInfo, ModelLoadOptions};
 
 pub struct GltfLoader;
 
 impl GltfLoader {
-    /// Traverses and loads all information from a GLTF/GLB node.
-    pub fn traverse_node(
+    /// Returns a stable identifier for a texture's image, meant to be resolved by a texture
+    /// loader later. External images are identified by their URI; images embedded in the file
+    /// itself (e.g. in a `.glb`) have no URI, so they're identified by their image index instead.
+    fn texture_id(texture: &Texture) -> String {
+        let image = texture.source();
+        match image.source() {
+            Source::Uri { uri, .. } => uri.to_string(),
+            Source::View { .. } => format!("embedded_image_{}", image.index()),
+        }
+    }
+
+    /// Loads a mesh from the given [`Document`] and vector of [`Data`], both specific to the glTF
+    /// file format.
+    fn load_mesh(&self, document: &Document, buffers: &Vec<BufferData>) -> Result<MeshLoadInfo> {
+        let mut vertices = Vec::new();
+        let mut normals = Vec::new();
+        let mut uvs = Vec::new();
+        let mut indices = Vec::<u32>::new();
+        let mut submeshes = Vec::new();
+
+        let scenes = document.scenes();
+
+        // We need to iterate through scenes and apply the transforms from each scene to their
+        // corresponding vertices.
+        for scene in scenes {
+            for node in scene.nodes() {
+                // Read through the nodes and get all vertex information.
+                // Even if there are multiple scenes, we're treating the whole file as a single mesh.
+                Self::mesh_traverse_node(
+                    &node,
+                    &Matrix4::identity(),
+                    &buffers,
+                    &mut vertices,
+                    &mut normals,
+                    &mut uvs,
+                    &mut indices,
+                    &mut submeshes,
+                );
+            }
+        }
+
+        let info = MeshLoadInfo {
+            vertices,
+            indices,
+            normals,
+            uvs,
+            submeshes,
+        };
+
+        Ok(info)
+    }
+
+    /// Traverses and loads all mesh information from a glTF/glB node.
+    pub fn mesh_traverse_node(
         node: &gltf::Node,
         parent_transform: &Matrix4<f32>,
-        buffers: &Vec<Data>,
+        buffers: &Vec<BufferData>,
         vertices: &mut Vec<[f32; 3]>,
         normals: &mut Vec<[f32; 3]>,
         uvs: &mut Vec<[f32; 3]>,
@@ -73,7 +127,7 @@ impl GltfLoader {
 
         // Process all child nodes as well
         for child in node.children() {
-            Self::traverse_node(
+            Self::mesh_traverse_node(
                 &child,
                 &full_transform,
                 &buffers,
@@ -86,62 +140,12 @@ impl GltfLoader {
         }
     }
 
-    /// Returns a stable identifier for a texture's image, meant to be resolved by a texture
-    /// loader later. External images are identified by their URI; images embedded in the file
-    /// itself (e.g. in a `.glb`) have no URI, so they're identified by their image index instead.
-    fn texture_id(texture: &Texture) -> String {
-        let image = texture.source();
-        match image.source() {
-            Source::Uri { uri, .. } => uri.to_string(),
-            Source::View { .. } => format!("embedded_image_{}", image.index()),
-        }
-    }
-
-    fn load_mesh(&self, path: &Path) -> Result<MeshLoadInfo> {
-        let (document, buffers, _) = gltf::import(path)?;
-
-        let mut vertices = Vec::new();
-        let mut normals = Vec::new();
-        let mut uvs = Vec::new();
-        let mut indices = Vec::<u32>::new();
-        let mut submeshes = Vec::new();
-
-        let scenes = document.scenes();
-
-        // We need to iterate through scenes and apply the transforms from each scene to their
-        // corresponding vertices.
-        println!("Parsing {} scenes from {:?}", scenes.len(), path);
-        for scene in scenes {
-            for node in scene.nodes() {
-                // Read through the nodes and get all vertex information.
-                // Even if there are multiple scenes, we're treating the whole file as a single mesh.
-                Self::traverse_node(
-                    &node,
-                    &Matrix4::identity(),
-                    &buffers,
-                    &mut vertices,
-                    &mut normals,
-                    &mut uvs,
-                    &mut indices,
-                    &mut submeshes,
-                );
-            }
-        }
-
-        let info = MeshLoadInfo {
-            vertices,
-            indices,
-            normals,
-            uvs,
-            submeshes,
-        };
-
-        Ok(info)
-    }
-
-    fn load_materials(&self, path: &Path) -> anyhow::Result<Vec<MaterialLoadInfo>> {
-        let (document, _buffers, _images) = gltf::import(path)?;
-
+    /// Loads all materials from the given [`Document`] and [`Data`] buffers. These are glTF/glB
+    /// specific.
+    ///
+    /// Note that this does not load any textures that are used with the materials, so this must
+    /// be called in tandem with [`GltfLoader::load_textures`].
+    fn load_materials(&self, document: &Document, buffers: &Vec<BufferData>) -> anyhow::Result<Vec<MaterialLoadInfo>> {
         // Collected in document order, so a material's position here matches the
         // `primitive.material().index()` that mesh loading recorded for its submeshes.
         Ok(document
@@ -180,7 +184,42 @@ impl GltfLoader {
             .collect())
     }
 
-    fn load_texture(&self, path: &Path) -> Result<TextureLoadInfo> {
+    /// Loads all textures from the given [`Document`] and [`Data`] buffers.
+    ///
+    /// Note that loading this does not load any materials that may use the textures, so this must
+    /// be called in tandem with [`GltfLoader::load_materials`].
+    fn load_textures(&self, document: &Document, buffers: &Vec<BufferData>, images: &Vec<ImageData>) -> Result<Vec<TextureLoadInfo>> {
         todo!()
     }
 }
+
+impl LoadModel for GltfLoader {
+    fn load_model(&self, path: &Path, options: ModelLoadOptions) -> Result<ModelLoadInfo> {
+        let mut info = ModelLoadInfo::default();
+
+        // First try to parse the file at the given path and get the information from it, then
+        // continue with processing.
+        let (document, buffers, images) = gltf::import(path)?;
+
+        if options.load_mesh {
+            // Load the mesh.
+            let mesh_info = self.load_mesh(&document, &buffers)?;
+            info.mesh = Some(mesh_info);
+        }
+
+        if options.load_materials {
+            // Load the materials.
+            let material_info = self.load_materials(&document, &buffers)?;
+            info.materials = Some(material_info);
+        }
+
+        // TODO Textures aren't currently supported.
+        // if options.load_textures {
+        //     // Load the textures.
+        //     let texture_info = self.load_textures(&document, &buffers, &images)?;
+        //     info.textures = Some(texture_info)
+        // }
+
+        Ok(info)
+    }
+}

src/assets/loaders/model_loader.rs

@@ -1,7 +1,9 @@
 use anyhow::Result;
 use std::collections::HashMap;
 use std::path::Path;
+use thiserror::Error;
 use crate::assets::loaders::common::{MaterialLoadInfo, MeshLoadInfo, TextureLoadInfo};
+use crate::assets::loaders::gltf_loader::GltfLoader;
 
 /// A trait for loading a model from a given path.
 pub trait LoadModel {
@@ -10,7 +12,7 @@ pub trait LoadModel {
 }
 
 /// The options applicable to loading a model.
-#[derive(Default, Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug)]
 pub struct ModelLoadOptions {
     /// Whether to load the full mesh.
     pub load_mesh: bool,
@@ -20,8 +22,27 @@ pub struct ModelLoadOptions {
     pub load_textures: bool,
 }
 
+impl Default for ModelLoadOptions {
+    fn default() -> Self {
+        Self {
+            load_mesh: true,
+            load_materials: true,
+            load_textures: true,
+        }
+    }
+}
+
+#[derive(Error, Debug, Clone)]
+pub enum ModelLoadError {
+    #[error("Extension was not found")]
+    ExtensionNotFound,
+    #[error("Extension {0} is not supported")]
+    ExtensionNotSupported(String),
+}
+
 /// Contains the information about the mesh, materials, and textures that this model has loaded.
 /// Each type of information will only be loaded if the caller indicates that they should be.
+#[derive(Default)]
 pub struct ModelLoadInfo {
     /// The loaded mesh, if applicable.
     pub mesh: Option<MeshLoadInfo>,
@@ -41,9 +62,25 @@ impl ModelLoader {
     /// Creates a new `ModelLoader` instance.
     pub fn new() -> Self {
         let mut loaders =  HashMap::new();
+        loaders.insert("gltf".into(), Box::new(GltfLoader) as Box<dyn LoadModel>);
+        loaders.insert("glb".into(), Box::new(GltfLoader));
 
         Self {
             loaders,
         }
     }
+
+    /// Loads a model from the given path. The available options are indicated by the [`ModelLoadOptions`]
+    /// struct.
+    pub fn load_model<P: AsRef<Path>>(&mut self, path: P, options: ModelLoadOptions) -> Result<ModelLoadInfo> {
+        // Determine which loader type to use.
+        let path = path.as_ref();
+        let ext = path.extension()
+            .ok_or(ModelLoadError::ExtensionNotFound)?
+            .to_str().unwrap();
+
+        self.loaders.get(ext)
+            .ok_or(ModelLoadError::ExtensionNotSupported(ext.into()))?
+            .load_model(path, options)
+    }
 }

src/assets/loaders/obj_loader.rs

@@ -1,10 +1,10 @@
-use crate::assets::loaders::mesh_loader::{LoadMesh, MeshLoadInfo, Submesh};
 use std::path::Path;
 use wavefront::Obj;
+use crate::assets::loaders::common::{MeshLoadInfo, Submesh};
 
 pub struct ObjLoader;
 
-impl LoadMesh for ObjLoader {
+impl ObjLoader {
     fn load_mesh(&self, path: &Path) -> anyhow::Result<MeshLoadInfo> {
         let obj_info = Obj::from_file(path).expect("Couldn't read wavefront file");
 

src/common/material.rs

@@ -1,5 +1,5 @@
-use crate::assets::loaders::mat_loader::MaterialLoadInfo;
 use std::collections::HashMap;
+use crate::assets::loaders::common::MaterialLoadInfo;
 
 pub struct MaterialRegistry {
     materials: HashMap<String, Material>

src/common/mesh.rs

@@ -1,9 +1,9 @@
-use crate::assets::loaders::mesh_loader::MeshLoadInfo;
 use crate::gpu::vertex3::Vertex3;
 use std::collections::HashMap;
 use std::sync::Arc;
 use vulkano::buffer::{Buffer, BufferCreateInfo, BufferUsage, Subbuffer};
 use vulkano::memory::allocator::{AllocationCreateInfo, MemoryAllocator, MemoryTypeFilter};
+use crate::assets::loaders::common::MeshLoadInfo;
 
 /// This struct is slightly misleading - it doesn't actually contain the mesh information, but
 /// the locations of the mesh's information in the overall application's vertex buffer, index buffer,