From cb6931f87b06528f8c37ead90227ea4a7b6c01c0 Mon Sep 17 00:00:00 2001
From: kyren <kerriganw@gmail.com>
Date: Sat, 6 Jun 2020 15:54:15 -0400
Subject: [PATCH] [rs] Properly honor `mapped_at_creation` in
 `Device::create_buffer`

The returned `Buffer` should immediately be mappable.  Fixes #351
---
 wgpu/src/lib.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/wgpu/src/lib.rs b/wgpu/src/lib.rs
index 246eeb2dc1..f484bea4cc 100644
--- a/wgpu/src/lib.rs
+++ b/wgpu/src/lib.rs
@@ -1108,10 +1108,14 @@ impl Device {
 
     /// Creates a new buffer.
     pub fn create_buffer(&self, desc: &BufferDescriptor) -> Buffer {
+        let mut map_context = MapContext::new(desc.size);
+        if desc.mapped_at_creation {
+            map_context.initial_range = 0..desc.size;
+        }
         Buffer {
             context: Arc::clone(&self.context),
             id: Context::device_create_buffer(&*self.context, &self.id, desc),
-            map_context: Mutex::new(MapContext::new(desc.size)),
+            map_context: Mutex::new(map_context),
         }
     }