hal/gles: fix dirty vertex buffers that are unused

wgpu-hal/src/gles/command.rs

@@ -28,6 +28,7 @@ pub(super) struct State {
     has_pass_label: bool,
     instance_vbuf_mask: usize,
     dirty_vbuf_mask: usize,
+    active_first_instance: u32,
     push_offset_to_uniform: ArrayVec<super::UniformDesc, { super::MAX_PUSH_CONSTANTS }>,
 }
 
@@ -91,34 +92,44 @@ impl super::CommandEncoder {
             .private_caps
             .contains(super::PrivateCapabilities::VERTEX_BUFFER_LAYOUT)
         {
-            for (index, &(ref vb_desc, ref vb)) in self.state.vertex_buffers.iter().enumerate() {
+            for (index, pair) in self.state.vertex_buffers.iter().enumerate() {
                 if self.state.dirty_vbuf_mask & (1 << index) == 0 {
                     continue;
                 }
-                let vb = vb.as_ref().unwrap();
-                let instance_offset = match vb_desc.step {
+                let (buffer_desc, vb) = match *pair {
+                    // Not all dirty bindings are necessarily filled. Some may be unused.
+                    (_, None) => continue,
+                    (ref vb_desc, Some(ref vb)) => (vb_desc.clone(), vb),
+                };
+                let instance_offset = match buffer_desc.step {
                     wgt::VertexStepMode::Vertex => 0,
-                    wgt::VertexStepMode::Instance => first_instance * vb_desc.stride,
+                    wgt::VertexStepMode::Instance => first_instance * buffer_desc.stride,
                 };
+
                 self.cmd_buffer.commands.push(C::SetVertexBuffer {
                     index: index as u32,
                     buffer: super::BufferBinding {
                         raw: vb.raw,
                         offset: vb.offset + instance_offset as wgt::BufferAddress,
                     },
-                    buffer_desc: vb_desc.clone(),
+                    buffer_desc,
                 });
+                self.state.dirty_vbuf_mask ^= 1 << index;
             }
         } else {
+            let mut vbuf_mask = 0;
             for attribute in self.state.vertex_attributes.iter() {
                 if self.state.dirty_vbuf_mask & (1 << attribute.buffer_index) == 0 {
                     continue;
                 }
-                let (buffer_desc, buffer) =
-                    self.state.vertex_buffers[attribute.buffer_index as usize].clone();
+                let (buffer_desc, vb) =
+                    match self.state.vertex_buffers[attribute.buffer_index as usize] {
+                        // Not all dirty bindings are necessarily filled. Some may be unused.
+                        (_, None) => continue,
+                        (ref vb_desc, Some(ref vb)) => (vb_desc.clone(), vb),
+                    };
 
                 let mut attribute_desc = attribute.clone();
-                let vb = buffer.unwrap();
                 attribute_desc.offset += vb.offset as u32;
                 if buffer_desc.step == wgt::VertexStepMode::Instance {
                     attribute_desc.offset += buffer_desc.stride * first_instance;
@@ -129,7 +140,9 @@ impl super::CommandEncoder {
                     buffer_desc,
                     attribute_desc,
                 });
+                vbuf_mask |= 1 << attribute.buffer_index;
             }
+            self.state.dirty_vbuf_mask ^= vbuf_mask;
         }
     }
 
@@ -151,13 +164,13 @@ impl super::CommandEncoder {
     }
 
     fn prepare_draw(&mut self, first_instance: u32) {
-        if first_instance != 0 {
+        if first_instance != self.state.active_first_instance {
+            // rebind all per-instance buffers on first-instance change
             self.state.dirty_vbuf_mask |= self.state.instance_vbuf_mask;
+            self.state.active_first_instance = first_instance;
         }
         if self.state.dirty_vbuf_mask != 0 {
             self.rebind_vertex_data(first_instance);
-            let vertex_rate_mask = self.state.dirty_vbuf_mask & !self.state.instance_vbuf_mask;
-            self.state.dirty_vbuf_mask ^= vertex_rate_mask;
         }
     }
 
@@ -539,6 +552,7 @@ impl crate::CommandEncoder<super::Api> for super::CommandEncoder {
         }
         self.state.instance_vbuf_mask = 0;
         self.state.dirty_vbuf_mask = 0;
+        self.state.active_first_instance = 0;
         self.state.color_targets.clear();
         self.state.vertex_attributes.clear();
         self.state.primitive = super::PrimitiveState::default();