feat: implement gltf loader

src/loaders/gltf_loader.rs

@@ -1,11 +1,47 @@
 use std::path::Path;
-use anyhow::Result;
+use anyhow::{anyhow, Result};
 use crate::loaders::mesh_loader::{MeshFileLoader, MeshInfo};
 
 pub struct GltfLoader;
 
 impl MeshFileLoader for GltfLoader {
     fn load_mesh(&self, path: &Path) -> Result<MeshInfo> {
-        todo!()
+        let scenes = easy_gltf::load(path)
+            .map_err(|e| anyhow!("could not load gltf file: {e}"))?;
+
+        println!("Found {} scene(s) in gltf file", scenes.len());
+
+        let scene = scenes.first()
+            .ok_or(anyhow!("no scenes in gltf file"))?;
+
+        println!("Found {} model(s) in gltf file", scene.models.len());
+
+        let mut vertices = Vec::new();
+        let mut normals = Vec::new();
+        let mut uvs = Vec::new();
+        let mut indices = Vec::<u32>::new();
+        for model in &scene.models {
+            // Indices must be offset by the number of vertices that are already registered.
+            let idx_offset = vertices.len() as u32;
+
+            // Put all vertex info together for a MeshInfo struct
+            for vertex in model.vertices() {
+                vertices.push(*vertex.position.as_ref());
+                normals.push(*vertex.normal.as_ref());
+                uvs.push([vertex.tex_coords.x, vertex.tex_coords.y, 0.0]);
+            }
+            model.indices()
+                .expect("failed to find indices")
+                .iter()
+                .map(|i| i + idx_offset)
+                .for_each(|i| indices.push(i));
+        }
+
+        Ok(MeshInfo {
+            vertices,
+            indices,
+            normals,
+            uvs
+        })
     }
 }