From e9c4e9e681db911efadc571ac54f96259753ec19 Mon Sep 17 00:00:00 2001
From: Florian RICHER <florian.richer@unova.fr>
Date: Thu, 9 Jun 2022 13:38:07 +0200
Subject: [PATCH] Add shader and pipeline

---
 engine_core/src/shader.wgsl | 19 ++++++++
 engine_core/src/state.rs    | 90 ++++++++++++++++++++++++++++++-------
 2 files changed, 94 insertions(+), 15 deletions(-)
 create mode 100644 engine_core/src/shader.wgsl

diff --git a/engine_core/src/shader.wgsl b/engine_core/src/shader.wgsl
new file mode 100644
index 0000000..01557fb
--- /dev/null
+++ b/engine_core/src/shader.wgsl
@@ -0,0 +1,19 @@
+struct VertexOutput {
+    [[builtin(position)]] clip_position: vec4<f32>;
+};
+
+[[stage(vertex)]]
+fn vs_main(
+    [[builtin(vertex_index)]] in_vertex_index: u32,
+) -> VertexOutput {
+    var out: VertexOutput;
+    let x = f32(1 - i32(in_vertex_index)) * 0.5;
+    let y = f32(i32(in_vertex_index & 1u) * 2 - 1) * 0.5;
+    out.clip_position = vec4<f32>(x, y, 0.0, 1.0);
+    return out;
+}
+
+[[stage(fragment)]]
+fn fs_main(in: VertexOutput) -> [[location(0)]] vec4<f32> {
+    return vec4<f32>(0.3, 0.2, 0.1, 1.0);
+}
diff --git a/engine_core/src/state.rs b/engine_core/src/state.rs
index e0aeffc..1b74e2b 100644
--- a/engine_core/src/state.rs
+++ b/engine_core/src/state.rs
@@ -6,6 +6,7 @@ pub struct State {
     pub queue: wgpu::Queue,
     pub config: wgpu::SurfaceConfiguration,
     pub size: winit::dpi::PhysicalSize<u32>,
+    render_pipeline: wgpu::RenderPipeline,
 }
 
 impl State {
@@ -59,12 +60,63 @@ impl State {
         };
         surface.configure(&device, &config);
 
+        let shader = device.create_shader_module(&wgpu::ShaderModuleDescriptor {
+            label: Some("Shader"),
+            source: wgpu::ShaderSource::Wgsl(include_str!("shader.wgsl").into()),
+        });
+
+        let render_pipeline_layout =
+        device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            label: Some("Render Pipeline Layout"),
+            bind_group_layouts: &[],
+            push_constant_ranges: &[],
+        });
+        
+        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: Some("Render Pipeline"),
+            layout: Some(&render_pipeline_layout),
+            vertex: wgpu::VertexState {
+                module: &shader,
+                entry_point: "vs_main",
+                buffers: &[],
+            },
+            fragment: Some(wgpu::FragmentState {
+                module: &shader,
+                entry_point: "fs_main",
+                targets: &[wgpu::ColorTargetState {
+                    format: config.format,
+                    blend: Some(wgpu::BlendState::REPLACE),
+                    write_mask: wgpu::ColorWrites::ALL,
+                }],
+            }),
+            primitive: wgpu::PrimitiveState {
+                topology: wgpu::PrimitiveTopology::TriangleList,
+                strip_index_format: None,
+                front_face: wgpu::FrontFace::Ccw,
+                cull_mode: Some(wgpu::Face::Back),
+                // Setting this to anything other than Fill requires Features::NON_FILL_POLYGON_MODE
+                polygon_mode: wgpu::PolygonMode::Fill,
+                // Requires Features::DEPTH_CLIP_CONTROL
+                unclipped_depth: false,
+                // Requires Features::CONSERVATIVE_RASTERIZATION
+                conservative: false,
+            },
+            depth_stencil: None,
+            multisample: wgpu::MultisampleState {
+                count: 1,
+                mask: !0,
+                alpha_to_coverage_enabled: false,
+            },
+            multiview: None,
+        });
+
         Self {
             surface,
             device,
             queue,
             config,
             size,
+            render_pipeline
         }
     }
 
@@ -78,7 +130,7 @@ impl State {
     }
 
     pub fn input(&mut self, event: &WindowEvent) -> bool {
-        log::info!("{:#?}", event);
+        // log::info!("{:#?}", event);
         false
     }
 
@@ -94,23 +146,31 @@ impl State {
         });
     
         {
-            let _render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                 label: Some("Render Pass"),
-                color_attachments: &[wgpu::RenderPassColorAttachment {
-                    view: &view,
-                    resolve_target: None,
-                    ops: wgpu::Operations {
-                        load: wgpu::LoadOp::Clear(wgpu::Color {
-                            r: 0.1,
-                            g: 0.2,
-                            b: 0.3,
-                            a: 1.0,
-                        }),
-                        store: true,
-                    },
-                }],
+                color_attachments: &[
+                    // This is what [[location(0)]] in the fragment shader targets
+                    wgpu::RenderPassColorAttachment {
+                        view: &view,
+                        resolve_target: None,
+                        ops: wgpu::Operations {
+                            load: wgpu::LoadOp::Clear(
+                                wgpu::Color {
+                                    r: 0.1,
+                                    g: 0.2,
+                                    b: 0.3,
+                                    a: 1.0,
+                                }
+                            ),
+                            store: true,
+                        }
+                    }
+                ],
                 depth_stencil_attachment: None,
             });
+
+            render_pass.set_pipeline(&self.render_pipeline); // 2.
+            render_pass.draw(0..3, 0..1);
         }
     
         // submit will accept anything that implements IntoIter