feat: properly implement GTLF/GLB loading

src/loaders/gltf_loader.rs

@@ -1,7 +1,8 @@
 use crate::loaders::mesh_loader::{MeshFileLoader, MeshInfo};
 use anyhow::Result;
 use std::path::Path;
-use nalgebra::{Matrix4, OMatrix, RowVector4};
+use gltf::buffer::Data;
+use nalgebra::{Matrix4, Vector4};
 
 pub struct GltfLoader;
 
@@ -10,53 +11,33 @@ impl GltfLoader {
     pub fn traverse_node(
         node: &gltf::Node,
         parent_transform: &Matrix4<f32>,
-        buffers: &[Vec<u8>],
+        buffers: &Vec<Data>,
         vertices: &mut Vec<[f32; 3]>,
         normals: &mut Vec<[f32; 3]>,
         uvs: &mut Vec<[f32; 3]>,
         indices: &mut Vec<u32>
     ) {
-
-    }
-}
-
-impl MeshFileLoader for GltfLoader {
-    fn load_mesh(&self, path: &Path) -> Result<MeshInfo> {
-        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 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() {
         let transform = node.transform().matrix()
             .iter()
             .flatten()
             .cloned()
             .collect::<Vec<f32>>();
-                let matrix = Matrix4::from_row_slice(transform.as_slice());
-                println!("Scene has transform: {}", matrix);
-            }
-        }
+        let matrix = Matrix4::from_column_slice(transform.as_slice());
+        let full_transform = parent_transform * matrix;
 
-        for mesh in document.meshes() {
+        if let Some(mesh) = node.mesh() {
+            // Read the mesh and apply the current transformation to every vertex
             for primitive in mesh.primitives() {
-                // Read the primitives as vertices and indices,
-                // and register a material for the primitive as well
                 let vert_offset = vertices.len() as u32;
 
                 let reader = primitive.reader(|buffer_index| Some(&buffers[buffer_index.index()]));
 
                 if let Some(positions) = reader.read_positions() {
                     for position in positions {
-                        vertices.push([position[0], position[2], -position[1]]);
+                        // Transform into a Vector4, apply transform, push as 3D slice
+                        let pos_vec = Vector4::new(position[0], position[1], position[2], 1.0);
+                        let transformed = full_transform * pos_vec;
+                        vertices.push([transformed.x, transformed.y, transformed.z]);
                     }
                 }
 
@@ -80,6 +61,51 @@ impl MeshFileLoader for GltfLoader {
             }
         }
 
+        // Process all child nodes as well
+        for child in node.children() {
+            Self::traverse_node(
+                &child,
+                &full_transform,
+                &buffers,
+                vertices,
+                normals,
+                uvs,
+                indices
+            );
+        }
+    }
+}
+
+impl MeshFileLoader for GltfLoader {
+    fn load_mesh(&self, path: &Path) -> Result<MeshInfo> {
+        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 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
+                );
+            }
+        }
+
         Ok(MeshInfo {
             vertices,
             indices,