Add buffer to buffer copies

next.json

@@ -260,6 +260,19 @@
             {
                 "name": "end render pass"
             },
+            {
+                "name": "copy buffer to buffer",
+                "args": [
+                    {"name": "source", "type": "buffer"},
+                    {"name": "source offset", "type": "uint32_t"},
+                    {"name": "destination", "type": "buffer"},
+                    {"name": "destination offset", "type": "uint32_t"},
+                    {"name": "size", "type": "uint32_t"}
+                ],
+                "TODO": [
+                    "Restrictions on the alignment of the copy? Cf Metal on OSX"
+                ]
+            },
             {
                 "name": "copy buffer to texture",
                 "args": [

src/backend/common/CommandBuffer.cpp

@@ -67,6 +67,12 @@ namespace backend {
                         begin->~BeginRenderPassCmd();
                     }
                     break;
+                case Command::CopyBufferToBuffer:
+                    {
+                        CopyBufferToBufferCmd* copy = commands->NextCommand<CopyBufferToBufferCmd>();
+                        copy->~CopyBufferToBufferCmd();
+                    }
+                    break;
                 case Command::CopyBufferToTexture:
                     {
                         CopyBufferToTextureCmd* copy = commands->NextCommand<CopyBufferToTextureCmd>();
@@ -201,6 +207,35 @@ namespace backend {
                     }
                     break;
 
+                case Command::CopyBufferToBuffer:
+                    {
+                        CopyBufferToBufferCmd* copy = iterator.NextCommand<CopyBufferToBufferCmd>();
+                        BufferBase* source = copy->source.Get();
+                        BufferBase* destination = copy->destination.Get();
+                        uint32_t sourceOffset = copy->sourceOffset;
+                        uint32_t destinationOffset = copy->destinationOffset;
+                        uint32_t size = copy->size;
+
+                        uint64_t sourceEnd = uint64_t(sourceOffset) + uint64_t(size);
+                        if (sourceEnd > uint64_t(source->GetSize())) {
+                            HandleError("Copy would read after end of the source buffer");
+                            return false;
+                        }
+
+                        uint64_t destinationEnd = uint64_t(destinationOffset) + uint64_t(size);
+                        if (destinationEnd > uint64_t(destination->GetSize())) {
+                            HandleError("Copy would read after end of the destination buffer");
+                            return false;
+                        }
+
+                        if (!state->ValidateCanCopy() ||
+                            !state->ValidateCanUseBufferAs(source, nxt::BufferUsageBit::TransferSrc) ||
+                            !state->ValidateCanUseBufferAs(destination, nxt::BufferUsageBit::TransferDst)) {
+                            return false;
+                        }
+                    }
+                    break;
+
                 case Command::CopyBufferToTexture:
                     {
                         CopyBufferToTextureCmd* copy = iterator.NextCommand<CopyBufferToTextureCmd>();
@@ -391,6 +426,16 @@ namespace backend {
         cmd->framebuffer = framebuffer;
     }
 
+    void CommandBufferBuilder::CopyBufferToBuffer(BufferBase* source, uint32_t sourceOffset, BufferBase* destination, uint32_t destinationOffset, uint32_t size) {
+        CopyBufferToBufferCmd* copy = allocator.Allocate<CopyBufferToBufferCmd>(Command::CopyBufferToBuffer);
+        new(copy) CopyBufferToBufferCmd;
+        copy->source = source;
+        copy->sourceOffset = sourceOffset;
+        copy->destination = destination;
+        copy->destinationOffset = destinationOffset;
+        copy->size = size;
+    }
+
     void CommandBufferBuilder::CopyBufferToTexture(BufferBase* buffer, uint32_t bufferOffset,
                                                    TextureBase* texture, uint32_t x, uint32_t y, uint32_t z,
                                                    uint32_t width, uint32_t height, uint32_t depth, uint32_t level) {

src/backend/common/CommandBuffer.h

@@ -61,6 +61,7 @@ namespace backend {
             // NXT API
             void AdvanceSubpass();
             void BeginRenderPass(RenderPassBase* renderPass, FramebufferBase* framebuffer);
+            void CopyBufferToBuffer(BufferBase* source, uint32_t sourceOffset, BufferBase* destination, uint32_t destinationOffset, uint32_t size);
             void CopyBufferToTexture(BufferBase* buffer, uint32_t bufferOffset,
                                      TextureBase* texture, uint32_t x, uint32_t y, uint32_t z,
                                      uint32_t width, uint32_t height, uint32_t depth, uint32_t level);

src/backend/common/Commands.h

@@ -30,6 +30,7 @@ namespace backend {
     enum class Command {
         AdvanceSubpass,
         BeginRenderPass,
+        CopyBufferToBuffer,
         CopyBufferToTexture,
         Dispatch,
         DrawArrays,
@@ -53,6 +54,14 @@ namespace backend {
         Ref<FramebufferBase> framebuffer;
     };
 
+    struct CopyBufferToBufferCmd {
+        Ref<BufferBase> source;
+        Ref<BufferBase> destination;
+        uint32_t sourceOffset;
+        uint32_t destinationOffset;
+        uint32_t size;
+    };
+
     struct CopyBufferToTextureCmd {
         Ref<BufferBase> buffer;
         uint32_t bufferOffset;

src/backend/d3d12/CommandBufferD3D12.cpp

@@ -61,6 +61,12 @@ namespace d3d12 {
                       }
                       break;
 
+                  case Command::CopyBufferToBuffer:
+                      {
+                          CopyBufferToBufferCmd* copy = commands.NextCommand<CopyBufferToBufferCmd>();
+                      }
+                      break;
+
                   case Command::CopyBufferToTexture:
                       {
                           CopyBufferToTextureCmd* copy = commands.NextCommand<CopyBufferToTextureCmd>();

src/backend/metal/MetalBackend.mm

@@ -376,6 +376,20 @@ namespace metal {
                     }
                     break;
 
+                case Command::CopyBufferToBuffer:
+                    {
+                        CopyBufferToBufferCmd* copy = commands.NextCommand<CopyBufferToBufferCmd>();
+
+                        encoders.EnsureBlit(commandBuffer);
+                        [encoders.blit
+                            copyFromBuffer:ToBackend(copy->source)->GetMTLBuffer()
+                            sourceOffset:copy->sourceOffset
+                            toBuffer:ToBackend(copy->destination)->GetMTLBuffer()
+                            destinationOffset:copy->destinationOffset
+                            size:copy->size];
+                    }
+                    break;
+
                 case Command::CopyBufferToTexture:
                     {
                         CopyBufferToTextureCmd* copy = commands.NextCommand<CopyBufferToTextureCmd>();

src/backend/opengl/CommandBufferGL.cpp

@@ -78,6 +78,19 @@ namespace opengl {
                     }
                     break;
 
+                case Command::CopyBufferToBuffer:
+                    {
+                        CopyBufferToBufferCmd* copy = commands.NextCommand<CopyBufferToBufferCmd>();
+
+                        glBindBuffer(GL_PIXEL_PACK_BUFFER, ToBackend(copy->source)->GetHandle());
+                        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, ToBackend(copy->destination)->GetHandle());
+                        glCopyBufferSubData(GL_PIXEL_PACK_BUFFER, GL_PIXEL_UNPACK_BUFFER, copy->sourceOffset, copy->destinationOffset, copy->size);
+
+                        glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
+                        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+                    }
+                    break;
+
                 case Command::CopyBufferToTexture:
                     {
                         CopyBufferToTextureCmd* copy = commands.NextCommand<CopyBufferToTextureCmd>();