From 5a98ac516b05827850c80e9c8d030713f5243ede Mon Sep 17 00:00:00 2001
From: Robert Swain <robert.swain@gmail.com>
Date: Wed, 3 Nov 2021 21:50:52 +0000
Subject: [PATCH] MSAA example (#3049)

Add an example that demonstrates the difference between no MSAA and MSAA 4x. This is also useful for testing panics when resizing the window using MSAA. This is on top of #3042 .

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
---
 Cargo.toml                    |  4 +++
 examples/3d/msaa_pipelined.rs | 68 +++++++++++++++++++++++++++++++++++
 examples/README.md            |  1 +
 3 files changed, 73 insertions(+)
 create mode 100644 examples/3d/msaa_pipelined.rs

diff --git a/Cargo.toml b/Cargo.toml
index 3a70ebdfda342a..68c8770fa6853c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -180,6 +180,10 @@ path = "examples/3d/load_gltf_pipelined.rs"
 name = "msaa"
 path = "examples/3d/msaa.rs"
 
+[[example]]
+name = "msaa_pipelined"
+path = "examples/3d/msaa_pipelined.rs"
+
 [[example]]
 name = "orthographic"
 path = "examples/3d/orthographic.rs"
diff --git a/examples/3d/msaa_pipelined.rs b/examples/3d/msaa_pipelined.rs
new file mode 100644
index 00000000000000..f259ed2a22b343
--- /dev/null
+++ b/examples/3d/msaa_pipelined.rs
@@ -0,0 +1,68 @@
+use bevy::{
+    ecs::prelude::*,
+    input::Input,
+    math::Vec3,
+    pbr2::{PbrBundle, PointLightBundle, StandardMaterial},
+    prelude::{App, Assets, KeyCode, Transform},
+    render2::{
+        camera::PerspectiveCameraBundle,
+        color::Color,
+        mesh::{shape, Mesh},
+        view::Msaa,
+    },
+    PipelinedDefaultPlugins,
+};
+
+/// This example shows how to configure Multi-Sample Anti-Aliasing. Setting the sample count higher
+/// will result in smoother edges, but it will also increase the cost to render those edges. The
+/// range should generally be somewhere between 1 (no multi sampling, but cheap) to 8 (crisp but
+/// expensive).
+/// Note that WGPU currently only supports 1 or 4 samples.
+/// Ultimately we plan on supporting whatever is natively supported on a given device.
+/// Check out this issue for more info: https://github.com/gfx-rs/wgpu/issues/1832
+fn main() {
+    println!("Press 'm' to toggle MSAA");
+    println!("Using 4x MSAA");
+    App::new()
+        .insert_resource(Msaa { samples: 4 })
+        .add_plugins(PipelinedDefaultPlugins)
+        .add_startup_system(setup)
+        .add_system(cycle_msaa)
+        .run();
+}
+
+/// set up a simple 3D scene
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
+    // cube
+    commands.spawn_bundle(PbrBundle {
+        mesh: meshes.add(Mesh::from(shape::Cube { size: 2.0 })),
+        material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
+        ..Default::default()
+    });
+    // light
+    commands.spawn_bundle(PointLightBundle {
+        transform: Transform::from_xyz(4.0, 8.0, 4.0),
+        ..Default::default()
+    });
+    // camera
+    commands.spawn_bundle(PerspectiveCameraBundle {
+        transform: Transform::from_xyz(-3.0, 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
+        ..Default::default()
+    });
+}
+
+fn cycle_msaa(input: Res<Input<KeyCode>>, mut msaa: ResMut<Msaa>) {
+    if input.just_pressed(KeyCode::M) {
+        if msaa.samples == 4 {
+            println!("Not using MSAA");
+            msaa.samples = 1;
+        } else {
+            println!("Using 4x MSAA");
+            msaa.samples = 4;
+        }
+    }
+}
diff --git a/examples/README.md b/examples/README.md
index 1717dcff09da9e..6d8a563bd8fb61 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -103,6 +103,7 @@ Example | File | Description
 `load_gltf_pipelined` | [`3d/load_gltf_pipelined.rs`](./3d/load_gltf_pipelined.rs) | Loads and renders a gltf file as a scene
 `many_cubes_pipelined` | [`3d/many_cubes_pipelined.rs`](./3d/many_cubes_pipelined.rs) | Simple benchmark to test per-entity draw overhead
 `msaa` | [`3d/msaa.rs`](./3d/msaa.rs) | Configures MSAA (Multi-Sample Anti-Aliasing) for smoother edges
+`msaa_pipelined` | [`3d/msaa_pipelined.rs`](./3d/msaa_pipelined.rs) | Configures MSAA (Multi-Sample Anti-Aliasing) for smoother edges
 `orthographic` | [`3d/orthographic.rs`](./3d/orthographic.rs) | Shows how to create a 3D orthographic view (for isometric-look games or CAD applications)
 `orthographic_pipelined` | [`3d/orthographic_pipelined.rs`](./3d/orthographic_pipelined.rs) | Shows how to create a 3D orthographic view (for isometric-look games or CAD applications)
 `parenting` | [`3d/parenting.rs`](./3d/parenting.rs) | Demonstrates parent->child relationships and relative transformations