From 8d88a5467568506fd9ebe3ae8676b93e5bec2081 Mon Sep 17 00:00:00 2001
From: "Elijah C. Voigt" <elijah.caine.mv@gmail.com>
Date: Mon, 5 Feb 2024 21:09:02 -0800
Subject: [PATCH] make the shader example closer to reality...

With Backup<T> and all that jazz...

I wonder if it will work in the real game!
---
 examples/shaders.rs | 75 +++++++++++++++++++++++++++++++++++++++------
 src/debug.rs        |  1 -
 src/main.rs         |  2 +-
 3 files changed, 66 insertions(+), 12 deletions(-)

diff --git a/examples/shaders.rs b/examples/shaders.rs
index cfde391..0e857d4 100644
--- a/examples/shaders.rs
+++ b/examples/shaders.rs
@@ -1,6 +1,5 @@
 use bevy::pbr::ExtendedMaterial;
 use bevy::pbr::MaterialExtension;
-use bevy::pbr::MaterialMeshBundle;
 use bevy::pbr::OpaqueRendererMethod;
 use bevy::prelude::*;
 use bevy::render::render_resource::*;
@@ -15,7 +14,14 @@ fn main() {
         ))
         .add_systems(Startup, setup)
         .add_systems(Update, rotate)
-        .add_systems(Update, setup_material)
+        .add_systems(Update, toggle_material.run_if(
+            |keys: Res<Input<KeyCode>>| -> bool {
+                keys.just_pressed(KeyCode::Space)
+            })
+        )
+        .add_systems(Update, init_materials.run_if(|events: Query<Entity, Added<Transform>>| -> bool {
+            !events.is_empty()
+        }))
         .run();
 }
 
@@ -52,29 +58,80 @@ impl MaterialExtension for MatExt {
     }
 }
 
-fn setup_material(
+
+#[derive(Debug, Component)]
+struct Backup<T: Component>(T);
+
+fn init_materials(
     events: Query<(Entity, &Handle<StandardMaterial>), Added<Handle<StandardMaterial>>>,
     standard_materials: Res<Assets<StandardMaterial>>,
     mut materials: ResMut<Assets<MyMat>>,
     mut commands: Commands,
 ) {
-    events.iter().for_each(|(entity, handle)| {
+    info!("initializing materials");
+
+    events.iter().for_each(|(entity, std_handle)| {
         // Extension we will add to existing gltf-sourced materials
         let extension = MatExt { cutoff: 1.0 };
         // Base material we will extend for the duration of the dissolve effect
         let mut base = standard_materials
-            .get(handle)
+            .get(std_handle)
             .expect("Resolve material data")
             .clone();
 
         base.opaque_render_method = OpaqueRendererMethod::Auto;
         base.alpha_mode = AlphaMode::Mask(0.5);
 
+        let ext_handle = materials.add(ExtendedMaterial { base, extension });
+
         commands
             .entity(entity)
-            .insert(materials.add(ExtendedMaterial { base, extension }))
-            .remove::<Handle<StandardMaterial>>();
-    })
+            .insert(Backup(ext_handle.clone()));
+    });
+}
+
+fn toggle_material(
+    query: Query<Entity, Or<(With<Handle<StandardMaterial>>, With<Handle<MyMat>>)>>,
+    std_mat: Query<(&Handle<StandardMaterial>, Option<&Backup<Handle<MyMat>>>)>,
+    ext_mat: Query<(&Handle<MyMat>, Option<&Backup<Handle<StandardMaterial>>>)>,
+    mut commands: Commands,
+) {
+    query.iter().for_each(|entity| {
+        // Entity has standard material, and had extended material
+        // Swap these materials
+        if let Ok(
+            (std_handle, Some(Backup(ext_handle)))
+        ) = std_mat.get(entity) {
+            info!("Swapping standard material for extended material");
+            commands
+                .entity(entity)
+                .insert(ext_handle.clone())
+                .insert(Backup(std_handle.clone()))
+                .remove::<Backup<Handle<MyMat>>>()
+                .remove::<Handle<StandardMaterial>>();
+
+            return
+        }
+
+        // In this branch we have the extended material assigned to the object
+        if let Ok(
+            (ext_handle, Some(Backup(std_handle)))
+        ) = ext_mat.get(entity) {
+            // Entity has standard material, and had extended material // Swap these materials
+            info!("Swapping extended material for standard material");
+
+            commands
+                .entity(entity)
+                .insert(std_handle.clone())
+                .insert(Backup(ext_handle.clone()))
+                .remove::<Backup<Handle<StandardMaterial>>>()
+                .remove::<Handle<MyMat>>();
+
+            return
+        }
+
+        panic!("What is happening?")
+    });
 }
 
 fn rotate(
@@ -84,8 +141,6 @@ fn rotate(
 ) {
     query.iter_mut().for_each(|mut t| {
         t.rotate_local_y(time.delta_seconds() / 2.0);
-        // t.rotate_local_z(time.delta_seconds() / 2.0);
-        // t.rotate_local_x(time.delta_seconds() / 2.0);
     });
     materials.iter_mut().for_each(|(_id, m)| {
         m.extension.cutoff = time.elapsed_seconds().sin().abs();
diff --git a/src/debug.rs b/src/debug.rs
index 3eb4cd8..3b64896 100644
--- a/src/debug.rs
+++ b/src/debug.rs
@@ -41,7 +41,6 @@ impl Plugin for DebugPlugin {
                 display_diagnostics.run_if(resource_exists::<DebugEnabled>()),
                 toggle_debug_ui.run_if(resource_changed_or_removed::<DebugEnabled>()),
                 camera_info.run_if(resource_exists::<DebugEnabled>()),
-                // gltf_info.run_if(on_event::<AssetEvent<Gltf>>()),
             ),
         );
     }
diff --git a/src/main.rs b/src/main.rs
index 8b53d44..21e1753 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -49,7 +49,7 @@ fn main() {
             .set(WindowPlugin {
                 primary_window: Some(Window {
                     title: "Martian Chess".into(),
-                    resolution: (640., 480.).into(),
+                    resolution: (1280.0, 720.0).into(),
                     ..default()
                 }),
                 ..default()