LOD GPU

lib/examples/demo.rs

@@ -11,7 +11,11 @@
 //!   * `R` resets the view, keys `1`/`2`/`3` jump to front / side / top presets,
 //!   * a **directional** light (the shadow caster) + a **point** light + a **spot** light,
 //!     so the shadow of the cube and the colored light halos are all visible,
-//!   * the primitives slowly rotate in `update`, so depth, lighting and shadows read clearly.
+//!   * the primitives slowly rotate in `update`, so depth, lighting and shadows read clearly,
+//!   * **LOD** (Step 19): the rounded primitives are created with three levels each
+//!     (`create_mesh_with_lod`, auto-decimated by halving targets); the CPU picks each entity's
+//!     level from its projected screen size (with hysteresis) — zoom in/out with the wheel and
+//!     the sphere/cylinder/cone/torus visibly lose detail as they shrink on screen.
 //!
 //! Doc (this header) follows the English convention used for examples; internal comments stay
 //! concise and French where helpful. Run with:
@@ -118,23 +122,38 @@ impl AppHandler for Demo {
         app.scene.add_entity("ground", "ground_mesh").unwrap();
 
         // 4. One mesh per primitive, each assigned to a textured (or stripe) material.
+        //    The cube + ground stay single-level (tiny meshes — LOD would buy nothing); the
+        //    rounded primitives get three LOD levels each (Step 19): level 0 is the full mesh,
+        //    levels 1.. are auto-generated by greedy decimation at halving targets (D10), all
+        //    packed into the mesh's single vertex/index buffers (D7). Zooming with the wheel
+        //    switches levels on the fly (asymmetric hysteresis, D4).
         app.scene
             .create_mesh("cube_mesh", cube(0.8), Some("solid_mat"))
             .unwrap();
         app.scene
-            .create_mesh("sphere_mesh", uv_sphere(0.55, 32, 20), Some("stripes_mat"))
+            .create_mesh_with_lod(
+                "sphere_mesh",
+                uv_sphere(0.55, 32, 20),
+                Some("stripes_mat"),
+                3,
+            )
             .unwrap();
         app.scene
-            .create_mesh("ico_mesh", icosphere(0.5, 2), Some("solid_mat"))
+            .create_mesh_with_lod("ico_mesh", icosphere(0.5, 2), Some("solid_mat"), 3)
             .unwrap();
         app.scene
-            .create_mesh("cyl_mesh", cylinder(0.4, 0.9, 32), Some("stripes_mat"))
+            .create_mesh_with_lod("cyl_mesh", cylinder(0.4, 0.9, 32), Some("stripes_mat"), 3)
             .unwrap();
         app.scene
-            .create_mesh("cone_mesh", cone(0.45, 0.9, 32), Some("solid_mat"))
+            .create_mesh_with_lod("cone_mesh", cone(0.45, 0.9, 32), Some("solid_mat"), 3)
             .unwrap();
         app.scene
-            .create_mesh("torus_mesh", torus(0.42, 0.16, 24, 16), Some("solid_mat"))
+            .create_mesh_with_lod(
+                "torus_mesh",
+                torus(0.42, 0.16, 24, 16),
+                Some("solid_mat"),
+                3,
+            )
             .unwrap();
 
         place("cube_e", "cube_mesh", app, 0);