From ea0e2830db3b78b8d73ac103eede3a9fe1717851 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Tue, 7 May 2024 20:25:26 +0200
Subject: refactor(engine): make Wavefront obj parser not create Mesh

---
 engine/src/file_format/wavefront/obj.rs | 174 ++++++++++++++++----------------
 1 file changed, 86 insertions(+), 88 deletions(-)

(limited to 'engine/src/file_format/wavefront/obj.rs')

diff --git a/engine/src/file_format/wavefront/obj.rs b/engine/src/file_format/wavefront/obj.rs
index d60b41d..884229c 100644
--- a/engine/src/file_format/wavefront/obj.rs
+++ b/engine/src/file_format/wavefront/obj.rs
@@ -14,14 +14,6 @@ use crate::util::try_option;
 use crate::vector::{Vec2, Vec3};
 use crate::vertex::{Builder as VertexBuilder, Vertex};
 
-/// The output from parsing the content of a Wavefront `.obj` using [`parse`].
-#[derive(Debug)]
-#[non_exhaustive]
-pub struct Obj
-{
-    pub mesh: Mesh,
-}
-
 /// Parses the content of a Wavefront `.obj`.
 ///
 /// # Errors
@@ -107,26 +99,40 @@ pub fn parse(obj_content: &str) -> Result<Obj, Error>
         })
         .collect::<Result<Vec<[FaceVertex; 3]>, _>>()?;
 
-    let vertices = faces
-        .iter()
-        .flatten()
-        .map(|face_vertex| {
-            face_vertex_to_vertex(
-                face_vertex,
-                Data {
-                    vertex_positions: &vertex_positions,
-                    texture_positions: &texture_positions,
-                    vertex_normals: &vertex_normals,
-                },
-            )
-        })
-        .collect::<Result<Vec<_>, Error>>()?;
-
     Ok(Obj {
-        mesh: Mesh::new(
+        vertex_positions,
+        vertex_normals,
+        texture_positions,
+        faces,
+    })
+}
+
+/// The output from parsing the content of a Wavefront `.obj` using [`parse`].
+#[derive(Debug)]
+#[non_exhaustive]
+pub struct Obj
+{
+    pub vertex_positions: Vec<Vec3<f32>>,
+    pub vertex_normals: Vec<Vec3<f32>>,
+    pub texture_positions: Vec<Vec2<f32>>,
+    pub faces: Vec<[FaceVertex; 3]>,
+}
+
+impl Obj
+{
+    pub fn to_mesh(&self) -> Result<Mesh, Error>
+    {
+        let vertices = self
+            .faces
+            .iter()
+            .flatten()
+            .map(|face_vertex| face_vertex.to_vertex(self))
+            .collect::<Result<Vec<_>, Error>>()?;
+
+        Ok(Mesh::new(
             vertices,
             Some(
-                faces
+                self.faces
                     .iter()
                     .flatten()
                     .enumerate()
@@ -135,55 +141,67 @@ pub fn parse(obj_content: &str) -> Result<Obj, Error>
                     })
                     .collect::<Result<Vec<_>, _>>()?,
             ),
-        ),
-    })
+        ))
+    }
 }
 
-struct Data<'a>
+#[derive(Debug)]
+pub struct FaceVertex
 {
-    vertex_positions: &'a [Vec3<f32>],
-    texture_positions: &'a [Vec2<f32>],
-    vertex_normals: &'a [Vec3<f32>],
+    pub position: u32,
+    pub texture: Option<u32>,
+    pub normal: Option<u32>,
 }
 
-fn face_vertex_to_vertex(face_vertex: &FaceVertex, data: Data) -> Result<Vertex, Error>
+impl FaceVertex
 {
-    let vertex_pos = *data
-        .vertex_positions
-        .get(face_vertex.position as usize - 1)
-        .ok_or(Error::FaceVertexPositionNotFound {
-            vertex_pos_index: face_vertex.position,
-        })?;
-
-    let face_vertex_texture = face_vertex
-        .texture
-        .ok_or(Error::NoFaceVertexTextureNotSupported)?;
-
-    let texture_pos = *data
-        .texture_positions
-        .get(face_vertex_texture as usize - 1)
-        .ok_or(Error::FaceTexturePositionNotFound {
-            texture_pos_index: face_vertex_texture,
-        })?;
-
-    let face_vertex_normal = face_vertex
-        .normal
-        .ok_or(Error::NoFaceVertexNormalNotSupported)?;
-
-    let vertex_normal = *data
-        .vertex_normals
-        .get(face_vertex_normal as usize - 1)
-        .ok_or(Error::FaceVertexNormalNotFound {
-            vertex_normal_index: face_vertex_normal,
-        })?;
-
-    Ok(VertexBuilder::new()
-        .pos(vertex_pos)
-        .color(Color::WHITE_F32)
-        .texture_coords(texture_pos)
-        .normal(vertex_normal)
-        .build()
-        .unwrap())
+    /// Tries to convert this face vertex into a [`Vertex`].
+    pub fn to_vertex(&self, obj: &Obj) -> Result<Vertex, Error>
+    {
+        let vertex_pos = *obj.vertex_positions.get(self.position as usize - 1).ok_or(
+            Error::FaceVertexPositionNotFound { vertex_pos_index: self.position },
+        )?;
+
+        let face_vertex_texture =
+            self.texture.ok_or(Error::NoFaceVertexTextureNotSupported)?;
+
+        let texture_pos = *obj
+            .texture_positions
+            .get(face_vertex_texture as usize - 1)
+            .ok_or(Error::FaceTexturePositionNotFound {
+                texture_pos_index: face_vertex_texture,
+            })?;
+
+        let face_vertex_normal =
+            self.normal.ok_or(Error::NoFaceVertexNormalNotSupported)?;
+
+        let vertex_normal = *obj
+            .vertex_normals
+            .get(face_vertex_normal as usize - 1)
+            .ok_or(Error::FaceVertexNormalNotFound {
+                vertex_normal_index: face_vertex_normal,
+            })?;
+
+        Ok(VertexBuilder::new()
+            .pos(vertex_pos)
+            .color(Color::WHITE_F32)
+            .texture_coords(texture_pos)
+            .normal(vertex_normal)
+            .build()
+            .unwrap())
+    }
+}
+
+impl From<Triplet> for FaceVertex
+{
+    fn from(triplet: Triplet) -> Self
+    {
+        Self {
+            position: triplet.0,
+            texture: triplet.1,
+            normal: triplet.2,
+        }
+    }
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -248,23 +266,3 @@ keyword! {
         F,
     }
 }
-
-#[derive(Debug)]
-struct FaceVertex
-{
-    position: u32,
-    texture: Option<u32>,
-    normal: Option<u32>,
-}
-
-impl From<Triplet> for FaceVertex
-{
-    fn from(triplet: Triplet) -> Self
-    {
-        Self {
-            position: triplet.0,
-            texture: triplet.1,
-            normal: triplet.2,
-        }
-    }
-}
-- 
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