library: render: mesh: load basic material from OBJ

pathtracer/src/core/color.rs

@@ -70,6 +70,25 @@ impl LinearColor {
         LinearColor { r, g, b }
     }
 
+    /// Creates a new `Color` from a slice.
+    ///
+    /// Panics if slice has less than 3 elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use pathtracer::core::LinearColor;
+    /// #
+    /// let color = LinearColor::new(&[1.0, 0.0, 0.0]); // bright red!
+    /// ```
+    pub fn from_slice(s: &[f32]) -> Self {
+        LinearColor {
+            r: s[0],
+            g: s[1],
+            b: s[2],
+        }
+    }
+
     #[must_use]
     /// Clamps the color's RGB components between 0.0 and 1.0.
     ///

pathtracer/src/render/mesh.rs

@@ -35,7 +35,7 @@ impl TryFrom<Wavefront> for Mesh {
     fn try_from(wavefront: Wavefront) -> Result<Mesh, Self::Error> {
         let mut shapes = Vec::new();
 
-        let (models, _materials) = load_obj(&wavefront.obj_file)?;
+        let (models, materials) = load_obj(&wavefront.obj_file)?;
 
         for model in models {
             let mesh = &model.mesh;
@@ -78,16 +78,24 @@ impl TryFrom<Wavefront> for Mesh {
 
                 // FIXME: handle material
                 let (material, texture): (MaterialEnum, TextureEnum) =
-                    if let Some(_) = mesh.material_id {
-                        (
-                            UniformMaterial::new(LightProperties::new(
-                                LinearColor::new(1.0, 0.0, 0.0),
-                                LinearColor::new(0.0, 0.0, 0.0),
-                                None,
-                            ))
-                            .into(),
-                            UniformTexture::new(LinearColor::new(0.5, 0.5, 0.5)).into(),
-                        )
+                    if let Some(mat_id) = mesh.material_id {
+                        let mesh_mat = &materials[mat_id];
+
+                        let diffuse = LinearColor::from_slice(&mesh_mat.ambient[..]);
+                        let specular = LinearColor::from_slice(&mesh_mat.ambient[..]);
+
+                        let material = UniformMaterial::new(LightProperties::new(
+                            diffuse.clone(),
+                            specular,
+                            // FIXME: material.dissolve is supposed to be "the alpha term"
+                            // Needs translation to our ReflTransEnum
+                            None,
+                        ));
+
+                        // we only handle uniform textures
+                        let texture = UniformTexture::new(diffuse);
+
+                        (material.into(), texture.into())
                     } else {
                         // FIXME: should we accept this, and use a default
                         // Material, or throw a LoadError