From 7c6edf31ccf551825afdaf0a7e40bd762b88faf1 Mon Sep 17 00:00:00 2001
From: "Elijah C. Voigt" <elijah.caine.mv@gmail.com>
Date: Tue, 16 Jan 2024 20:28:30 -0800
Subject: [PATCH] Saving my place w/ shader example

---
 assets/examples/images/texture.png    |  3 +
 assets/examples/shaders/dissolve.wgsl | 57 ++++++++++++++++++
 examples/shaders.rs                   | 85 +++++++++++++++++++++++++++
 3 files changed, 145 insertions(+)
 create mode 100644 assets/examples/images/texture.png
 create mode 100644 assets/examples/shaders/dissolve.wgsl
 create mode 100644 examples/shaders.rs

diff --git a/assets/examples/images/texture.png b/assets/examples/images/texture.png
new file mode 100644
index 0000000..725852b
--- /dev/null
+++ b/assets/examples/images/texture.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:fbbafd145de1c0ee8643c72bda2dfd936810b5488411c34b7ce8ff49217fad08
+size 12064
diff --git a/assets/examples/shaders/dissolve.wgsl b/assets/examples/shaders/dissolve.wgsl
new file mode 100644
index 0000000..d61a121
--- /dev/null
+++ b/assets/examples/shaders/dissolve.wgsl
@@ -0,0 +1,57 @@
+#import bevy_pbr::{
+	pbr_fragment::pbr_input_from_standard_material,
+	forward_io::{VertexOutput, FragmentOutput},
+	mesh_view_bindings::globals,
+	pbr_functions::{
+		alpha_discard,
+		apply_pbr_lighting,
+		main_pass_post_lighting_processing
+	},
+}
+
+struct MatExt {
+	step: u32,
+}
+
+@group(1) @binding(100)
+var<uniform> mat_ext: MatExt;
+
+fn random(st: vec2<f32>) -> f32 {
+	var a = vec2(12.9898, 78.233);
+	var b = 43758.5453123;
+	return fract(sin(dot(st.xy, a)) * b);
+}
+
+fn noise(st: vec2<f32>) -> f32 {
+	var i = floor(st);
+	var f = floor(st);
+
+	var a = random(i);
+	var b = random(i + vec2(1.0, 0.0));
+	var c = random(i + vec2(0.0, 1.0));
+	var d = random(i + vec2(1.0, 1.0));
+
+	var u = smoothstep(vec2(0.0), vec2(1.0), f);
+
+	return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
+}
+
+@fragment
+fn fragment(
+	in: VertexOutput,
+	@builtin(front_facing) is_front: bool,
+) -> FragmentOutput {
+	var pbr_input = pbr_input_from_standard_material(in, is_front);
+	pbr_input.material.base_color.b = pbr_input.material.base_color.r;
+
+	var out: FragmentOutput;
+	out.color = apply_pbr_lighting(pbr_input);
+
+	var pos = vec2(in.uv * 5.0) + vec2(globals.time);
+
+	var n = noise(pos);
+
+	out.color = vec4(vec3(n), abs(sin(globals.time)));
+
+	return out;
+}
\ No newline at end of file
diff --git a/examples/shaders.rs b/examples/shaders.rs
new file mode 100644
index 0000000..5d29f83
--- /dev/null
+++ b/examples/shaders.rs
@@ -0,0 +1,85 @@
+use bevy::pbr::OpaqueRendererMethod;
+use bevy::prelude::*;
+use bevy::pbr::ExtendedMaterial;
+use bevy::pbr::MaterialExtension;
+use bevy::pbr::MaterialMeshBundle;
+use bevy::render::render_resource::*;
+
+type MyMat = ExtendedMaterial<StandardMaterial, MatExt>;
+
+fn main() {
+	App::new()
+		.add_plugins((
+			DefaultPlugins.set(ImagePlugin::default_nearest()),
+			MaterialPlugin::<MyMat>::default(),
+		))
+		.add_systems(Startup, setup)
+		.add_systems(Update, rotate)
+		.run();
+}
+
+fn setup(
+	mut commands: Commands,
+	mut meshes: ResMut<Assets<Mesh>>,
+	mut materials: ResMut<Assets<MyMat>>,
+) {
+	commands.spawn(MaterialMeshBundle {
+		mesh: meshes.add(
+			Mesh::try_from(shape::UVSphere {
+				radius: 1.0,
+				..default()
+			}).unwrap(),
+		),
+		transform: Transform::from_xyz(0.0, 0.5, 0.0),
+		material: materials.add(ExtendedMaterial {
+			base: StandardMaterial {
+				base_color: Color::RED,
+				opaque_render_method: OpaqueRendererMethod::Forward,
+				alpha_mode: AlphaMode::Mask(0.5),
+				..default()
+			},
+			extension: MatExt { step: 3 },
+		}),
+		..default()
+	});
+
+	commands.spawn(PointLightBundle { 
+		point_light: PointLight {
+			intensity: 10.0,
+			..default()
+		},
+		transform: Transform::from_xyz(-1.0, 4.5, 4.0).looking_at(Vec3::ZERO, Vec3::Y),
+		..default()
+	});
+
+	commands.spawn(Camera3dBundle {
+		transform: Transform::from_xyz(-1.0, 1.5, 4.0).looking_at(Vec3::ZERO, Vec3::Y),
+		..default()
+	});
+}
+
+#[derive(Asset, AsBindGroup, Reflect, Debug, Clone)]
+struct MatExt {
+	#[uniform(100)]
+	step: u32,
+}
+
+impl MaterialExtension for MatExt {
+	fn fragment_shader() -> ShaderRef {
+		"examples/shaders/dissolve.wgsl".into()
+	}
+	fn deferred_fragment_shader() -> ShaderRef {
+		"examples/shaders/dissolve.wgsl".into()
+	}
+}
+
+fn rotate(
+	mut query: Query<&mut Transform, With<Handle<Mesh>>>,
+	time: Res<Time>,
+) {
+	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);
+	})
+}
\ No newline at end of file