Index buffer

Source/Main.rs

@@ -43,6 +43,11 @@ const VERTICES: &[Vertex] = &[
     Vertex { position: [0.5, -0.5, 0.0], color: [0.0, 0.0, 1.0] },
 ];
 
+#[rustfmt::skip]
+const INDICES: &[u16] = &[
+    0, 1, 2,
+];
+
 struct State {
     surface: wgpu::Surface,
     device: wgpu::Device,
@@ -51,7 +56,8 @@ struct State {
     size: winit::dpi::PhysicalSize<u32>,
     render_pipeline: wgpu::RenderPipeline,
     vertex_buffer: wgpu::Buffer,
-    num_vertices: u32,
+    index_buffer: wgpu::Buffer,
+    num_indices: u32,
 }
 
 impl State {
@@ -152,7 +158,13 @@ impl State {
             usage: wgpu::BufferUsages::VERTEX,
         });
 
-        let num_vertices = VERTICES.len() as u32;
+        let index_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("Index Buffer"),
+            contents: bytemuck::cast_slice(INDICES),
+            usage: wgpu::BufferUsages::INDEX,
+        });
+
+        let num_indices = INDICES.len() as u32;
 
         Self {
             surface,
@@ -162,7 +174,8 @@ impl State {
             size,
             render_pipeline,
             vertex_buffer,
-            num_vertices,
+            index_buffer,
+            num_indices,
         }
     }
 
@@ -217,8 +230,8 @@ impl State {
 
             render_pass.set_pipeline(&self.render_pipeline);
             render_pass.set_vertex_buffer(0, self.vertex_buffer.slice(..));
-
-            render_pass.draw(0..self.num_vertices, 0..1);
+            render_pass.set_index_buffer(self.index_buffer.slice(..), wgpu::IndexFormat::Uint16);
+            render_pass.draw_indexed(0..self.num_indices, 0, 0..1);
         }
 
         // submit will accept anything that implements IntoIter