Indirect cube

FredrikNoren · Nov 2, 2021 · 7da68cb · 7da68cb
1 parent ca7ca74
commit 7da68cb
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Showing 3 changed files with 39 additions and 3 deletions.
diff --git a/wgpu-hal/src/metal/adapter.rs b/wgpu-hal/src/metal/adapter.rs
@@ -875,7 +875,8 @@ impl super::PrivateCapabilities {
             | F::VERTEX_WRITABLE_STORAGE
             | F::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES
             | F::POLYGON_MODE_LINE
-            | F::CLEAR_COMMANDS;
+            | F::CLEAR_COMMANDS
+            | F::MULTI_DRAW_INDIRECT;
 
         features.set(F::DEPTH_CLAMPING, self.supports_depth_clamping);
 

diff --git a/wgpu/examples/cube/main.rs b/wgpu/examples/cube/main.rs
@@ -83,6 +83,16 @@ fn create_texels(size: usize) -> Vec<u8> {
         .collect()
 }
 
+#[repr(C)]
+#[derive(Debug, Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct DrawIndexedIndirect {
+    vertex_count: u32,
+    instance_count: u32,
+    base_index: u32,
+    vertex_offset: i32,
+    base_instance: u32,
+}
+
 struct Example {
     vertex_buf: wgpu::Buffer,
     index_buf: wgpu::Buffer,
@@ -91,6 +101,7 @@ struct Example {
     uniform_buf: wgpu::Buffer,
     pipeline: wgpu::RenderPipeline,
     pipeline_wire: Option<wgpu::RenderPipeline>,
+    commands: wgpu::Buffer,
 }
 
 impl Example {
@@ -110,6 +121,9 @@ impl framework::Example for Example {
     fn optional_features() -> wgt::Features {
         wgt::Features::POLYGON_MODE_LINE
     }
+    fn required_features() -> wgpu::Features {
+        wgt::Features::MULTI_DRAW_INDIRECT
+    }
 
     fn init(
         config: &wgpu::SurfaceConfiguration,
@@ -133,6 +147,24 @@ impl framework::Example for Example {
             usage: wgpu::BufferUsages::INDEX,
         });
 
+        let commands = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("Commands Buffer"),
+            contents: bytemuck::cast_slice(&[DrawIndexedIndirect {
+                vertex_count: index_data.len() as u32,
+                instance_count: 1,
+                base_index: 0,
+                vertex_offset: 0,
+                base_instance: 0,
+            }, DrawIndexedIndirect {
+                vertex_count: index_data.len() as u32,
+                instance_count: 1,
+                base_index: 0,
+                vertex_offset: 0,
+                base_instance: 1,
+            }]),
+            usage: wgpu::BufferUsages::INDIRECT,
+        });
+
         // Create pipeline layout
         let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
             label: None,
@@ -310,6 +342,7 @@ impl framework::Example for Example {
             uniform_buf,
             pipeline,
             pipeline_wire,
+            commands,
         }
     }
 
@@ -362,7 +395,8 @@ impl framework::Example for Example {
             rpass.set_vertex_buffer(0, self.vertex_buf.slice(..));
             rpass.pop_debug_group();
             rpass.insert_debug_marker("Draw!");
-            rpass.draw_indexed(0..self.index_count as u32, 0, 0..1);
+            rpass.multi_draw_indexed_indirect(&self.commands, 0, 2);
+            // rpass.draw_indexed(0..self.index_count as u32, 0, 0..1);
             if let Some(ref pipe) = self.pipeline_wire {
                 rpass.set_pipeline(pipe);
                 rpass.draw_indexed(0..self.index_count as u32, 0, 0..1);

diff --git a/wgpu/examples/cube/shader.wgsl b/wgpu/examples/cube/shader.wgsl
@@ -14,10 +14,11 @@ var<uniform> r_locals: Locals;
 fn vs_main(
     [[location(0)]] position: vec4<f32>,
     [[location(1)]] tex_coord: vec2<f32>,
+    [[builtin(instance_index)]] instance_index: u32
 ) -> VertexOutput {
     var out: VertexOutput;
     out.tex_coord = tex_coord;
-    out.position = r_locals.transform * position;
+    out.position = r_locals.transform * (position + vec4<f32>(f32(instance_index) * 2.5, 0., 0., 0.));
     return out;
 }