add cube primitive wip

src/smesh/mod.rs

@@ -16,8 +16,8 @@ pub mod iterators;
 pub mod loops;
 pub mod mesh_query;
 pub mod model;
+pub mod primitives;
 pub mod selection;
 pub mod topological_operations;
 pub mod transform;
 pub mod util;
-

src/smesh/primitives.rs

@@ -0,0 +1,49 @@
+use glam::vec3;
+
+use crate::prelude::*;
+
+pub struct Cube {
+    pub subdivisions: usize,
+}
+
+pub struct CubeData {
+    pub front_bottom_left_vertex: VertexId,
+}
+
+impl Cube {
+    pub fn generate(self) -> SMeshResult<(SMesh, CubeData)> {
+        // Construct SMesh
+        let mut smesh = SMesh::new();
+        let half_extent = 0.5;
+        let v0 = smesh.add_vertex(vec3(-half_extent, -half_extent, half_extent));
+        let v1 = smesh.add_vertex(vec3(half_extent, -half_extent, half_extent));
+        let v2 = smesh.add_vertex(vec3(half_extent, half_extent, half_extent));
+        let v3 = smesh.add_vertex(vec3(-half_extent, half_extent, half_extent));
+
+        let v4 = smesh.add_vertex(vec3(-half_extent, -half_extent, -half_extent));
+        let v5 = smesh.add_vertex(vec3(half_extent, -half_extent, -half_extent));
+        let v6 = smesh.add_vertex(vec3(half_extent, half_extent, -half_extent));
+        let v7 = smesh.add_vertex(vec3(-half_extent, half_extent, -half_extent));
+
+        // Front
+        smesh.make_face(vec![v0, v1, v2, v3])?;
+        // Right
+        smesh.make_face(vec![v1, v5, v6, v2])?;
+        // Back
+        smesh.make_face(vec![v5, v4, v7, v6])?;
+        // Left
+        smesh.make_face(vec![v4, v0, v3, v7])?;
+        // Top
+        smesh.make_face(vec![v3, v2, v6, v7])?;
+        // Bottom
+        smesh.make_face(vec![v4, v5, v1, v0])?;
+
+        smesh.recalculate_normals()?;
+        Ok((
+            smesh,
+            CubeData {
+                front_bottom_left_vertex: v0,
+            },
+        ))
+    }
+}