[Merged by Bors] - Expose draw indirect

crates/bevy_render/src/render_phase/draw_state.rs

@@ -1,7 +1,7 @@
 use crate::{
     prelude::Color,
     render_resource::{
-        BindGroup, BindGroupId, BufferId, BufferSlice, RenderPipeline, RenderPipelineId,
+        BindGroup, BindGroupId, Buffer, BufferId, BufferSlice, RenderPipeline, RenderPipelineId,
         ShaderStages,
     },
 };
@@ -233,9 +233,61 @@ impl<'a> TrackedRenderPass<'a> {
         self.pass.draw_indexed(indices, base_vertex, instances);
     }
 
+    /// Draws primitives from the active vertex buffer(s) based on the contents of the `indirect_buffer`.
+    ///
+    /// The active vertex buffers can be set with [`TrackedRenderPass::set_vertex_buffer`].
+    ///
+    /// The structure expected in `indirect_buffer` is the following:
+    ///
+    /// ```rust
+    /// #[repr(C)]
+    /// struct DrawIndirect {
+    ///     vertex_count: u32, // The number of vertices to draw.
+    ///     instance_count: u32, // The number of instances to draw.
+    ///     first_vertex: u32, // The Index of the first vertex to draw.
+    ///     first_instance: u32, // The instance ID of the first instance to draw.
+    ///     // has to be 0, unless [`Features::INDIRECT_FIRST_INSTANCE`] is enabled.
+    /// }
+    /// ```
+    pub fn draw_indirect(&mut self, indirect_buffer: &'a Buffer, indirect_offset: u64) {
+        trace!("draw indirect: {:?} {}", indirect_buffer, indirect_offset);
+        self.pass.draw_indirect(indirect_buffer, indirect_offset);
+    }
+
+    /// Draws indexed primitives using the active index buffer and the active vertex buffers,
+    /// based on the contents of the `indirect_buffer`.
+    ///
+    /// The active index buffer can be set with [`TrackedRenderPass::set_index_buffer`], while the active
+    /// vertex buffers can be set with [`TrackedRenderPass::set_vertex_buffer`].
+    ///
+    /// The structure expected in `indirect_buffer` is the following:
+    ///
+    /// ```rust
+    /// #[repr(C)]
+    /// struct DrawIndexedIndirect {
+    ///     vertex_count: u32, // The number of vertices to draw.
+    ///     instance_count: u32, // The number of instances to draw.
+    ///     first_index: u32, // The base index within the index buffer.
+    ///     vertex_offset: i32, // The value added to the vertex index before indexing into the vertex buffer.
+    ///     first_instance: u32, // The instance ID of the first instance to draw.
+    ///     // has to be 0, unless [`Features::INDIRECT_FIRST_INSTANCE`] is enabled.
+    /// }
+    /// ```
+    pub fn draw_indexed_indirect(&mut self, indirect_buffer: &'a Buffer, indirect_offset: u64) {
+        trace!(
+            "draw indexed indirect: {:?} {}",
+            indirect_buffer,
+            indirect_offset
+        );
+        self.pass
+            .draw_indexed_indirect(indirect_buffer, indirect_offset);
+    }
+
+    /// Sets the stencil reference.
+    ///
+    /// Subsequent stencil tests will test against this value.
     pub fn set_stencil_reference(&mut self, reference: u32) {
         trace!("set stencil reference: {}", reference);
-
         self.pass.set_stencil_reference(reference);
     }