[Vk] Align mapping to nonCoherentAtomSize

Author: TechPizzaDev

src/Veldrid/MapMode.cs

@@ -9,24 +9,30 @@ public enum MapMode : byte
         /// <summary>
         /// A read-only resource mapping. The mapped data region is not writable, and cannot be used to transfer data into the
         /// graphics resource.
-        /// NOTE: This mode can only be used on resources created with the Staging usage flag.
         /// </summary>
+        /// <remarks>
+        /// This mode can only be used on resources created with the Staging usage flag.
+        /// </remarks>
         Read = 1 << 0,
 
         /// <summary>
         /// A write-only resource mapping. The mapped data region is writable, and will be transferred into the graphics resource
         /// when <see cref="GraphicsDevice.Unmap(MappableResource, uint)"/> is called.
-        /// NOTE: upon mapping a buffer with this
+        /// </summary>
+        /// <remarks>
+        /// Upon mapping a buffer with this
         /// mode, the previous contents of the resource will be erased. This mode can only be used to entirely replace the
         /// contents of a resource.
-        /// </summary>
+        /// </remarks>
         Write = 1 << 1,
 
         /// <summary>
         /// A read-write resource mapping. The mapped data region is both readable and writable.
-        /// NOTE: this mode can only be used
-        /// on resources created with the Staging usage flag.
         /// </summary>
+        /// <remarks>
+        /// This mode can only be used
+        /// on resources created with the Staging usage flag.
+        /// </remarks>
         ReadWrite = Write | Read,
     }
 }

src/Veldrid/Vk/VkGraphicsDevice.cs

@@ -1005,7 +1005,6 @@ private protected override MappedResource MapCore(
             if (resource is VkBuffer buffer)
             {
                 memoryBlock = buffer.Memory;
-                sizeInBytes = buffer.SizeInBytes;
             }
             else
             {
@@ -1020,15 +1019,20 @@ private protected override MappedResource MapCore(
 
             if (memoryBlock.DeviceMemory != VkDeviceMemory.NULL)
             {
+                ulong atomSize = _physicalDeviceProperties.limits.nonCoherentAtomSize;
+                ulong mapOffset = memoryBlock.Offset + offsetInBytes;
+                ulong bindOffset = ((mapOffset / atomSize) * atomSize);
+                ulong bindSize = ((sizeInBytes + atomSize - 1) / atomSize) * atomSize;
+
                 if (memoryBlock.IsPersistentMapped)
                 {
-                    mappedPtr = (IntPtr)memoryBlock.BlockMappedPointer;
+                    mappedPtr = (IntPtr)((byte*)memoryBlock.BaseMappedPointer + mapOffset);
                 }
                 else
                 {
                     void* ret;
                     VkResult result = vkMapMemory(
-                        _device, memoryBlock.DeviceMemory, memoryBlock.Offset, memoryBlock.Size, 0, &ret);
+                        _device, memoryBlock.DeviceMemory, bindOffset, bindSize, 0, &ret);
                     if (result != VkResult.VK_ERROR_MEMORY_MAP_FAILED)
                     {
                         CheckResult(result);
@@ -1037,15 +1041,14 @@ private protected override MappedResource MapCore(
                     {
                         ThrowMapFailedException(resource, subresource);
                     }
-                    mappedPtr = (IntPtr)ret;
+                    mappedPtr = (IntPtr)((byte*)ret + (mapOffset - bindOffset));
                 }
             }
 
-            byte* dataPtr = (byte*)mappedPtr.ToPointer() + offsetInBytes;
             return new MappedResource(
                 resource,
                 mode,
-                (IntPtr)dataPtr,
+                mappedPtr,
                 offsetInBytes,
                 sizeInBytes,
                 subresource,
@@ -1280,7 +1283,7 @@ internal VkCommandList GetAndBeginCommandList()
                 {
                     Transient = true
                 };
-                sharedList = (VkCommandList) ResourceFactory.CreateCommandList(desc);
+                sharedList = (VkCommandList)ResourceFactory.CreateCommandList(desc);
             }
 
             sharedList.Begin();