D3D12 vertex and index buffers with resource transitions
diff --git a/src/backend/d3d12/InputStateD3D12.cpp b/src/backend/d3d12/InputStateD3D12.cpp
new file mode 100644
index 0000000..e0abcb0
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+++ b/src/backend/d3d12/InputStateD3D12.cpp
@@ -0,0 +1,82 @@
+// Copyright 2017 The NXT Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "InputStateD3D12.h"
+
+namespace backend {
+namespace d3d12 {
+
+    static DXGI_FORMAT VertexFormatType(nxt::VertexFormat format) {
+        switch (format) {
+            case nxt::VertexFormat::FloatR32G32B32A32:
+                return DXGI_FORMAT_R32G32B32A32_FLOAT;
+            case nxt::VertexFormat::FloatR32G32B32:
+                return DXGI_FORMAT_R32G32B32_FLOAT;
+            case nxt::VertexFormat::FloatR32G32:
+                return DXGI_FORMAT_R32G32_FLOAT;
+        }
+    }
+
+    static D3D12_INPUT_CLASSIFICATION InputStepModeFunction(nxt::InputStepMode mode) {
+        switch (mode) {
+            case nxt::InputStepMode::Vertex:
+                return D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA;
+            case nxt::InputStepMode::Instance:
+                return D3D12_INPUT_CLASSIFICATION_PER_INSTANCE_DATA;
+        }
+    }
+
+    InputState::InputState(Device* device, InputStateBuilder* builder)
+        : InputStateBase(builder), device(device) {
+
+        const auto& attributesSetMask = GetAttributesSetMask();
+
+        size_t count = 0;
+        for (size_t i = 0; i < attributesSetMask.size(); ++i) {
+            if (!attributesSetMask[i]) {
+                continue;
+            }
+
+            D3D12_INPUT_ELEMENT_DESC& inputElementDescriptor = inputElementDescriptors[count++];
+
+            const AttributeInfo& attribute = GetAttribute(i);
+
+            // If the HLSL semantic is TEXCOORDN the SemanticName should be "TEXCOORD" and the SemanticIndex N
+            inputElementDescriptor.SemanticName = "TEXCOORD";
+            inputElementDescriptor.SemanticIndex = i;
+            inputElementDescriptor.Format = VertexFormatType(attribute.format);
+            inputElementDescriptor.InputSlot = attribute.bindingSlot;
+
+            const InputInfo& input = GetInput(attribute.bindingSlot);
+
+            inputElementDescriptor.AlignedByteOffset = attribute.offset;
+            inputElementDescriptor.InputSlotClass = InputStepModeFunction(input.stepMode);
+            if (inputElementDescriptor.InputSlotClass == D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA) {
+                inputElementDescriptor.InstanceDataStepRate = 0;
+            } else {
+                inputElementDescriptor.InstanceDataStepRate = 1;
+            }
+        }
+
+        inputLayoutDescriptor.pInputElementDescs = inputElementDescriptors;
+        inputLayoutDescriptor.NumElements = count;
+
+    }
+
+    const D3D12_INPUT_LAYOUT_DESC& InputState::GetD3D12InputLayoutDescriptor() const {
+        return inputLayoutDescriptor;
+    }
+
+}
+}