Make the index format part of the pipeline state.

examples/HelloDepthStencil.cpp

@@ -222,6 +222,7 @@ void init() {
         .SetLayout(pl)
         .SetStage(nxt::ShaderStage::Vertex, vsModule, "main")
         .SetStage(nxt::ShaderStage::Fragment, fsModule, "main")
+        .SetIndexFormat(nxt::IndexFormat::Uint32)
         .SetInputState(inputState)
         .SetDepthStencilState(depthStencilState)
         .GetResult();
@@ -286,7 +287,7 @@ void frame() {
             .TransitionBufferUsage(cameraBuffer, nxt::BufferUsageBit::Uniform)
             .SetBindGroup(0, bindGroup[0])
             .SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets)
-            .SetIndexBuffer(indexBuffer, 0, nxt::IndexFormat::Uint32)
+            .SetIndexBuffer(indexBuffer, 0)
             .DrawElements(36, 1, 0, 0)
 
             .SetStencilReference(0x1)

examples/HelloIndices.cpp

@@ -81,6 +81,7 @@ void init() {
         .SetSubpass(renderpass, 0)
         .SetStage(nxt::ShaderStage::Vertex, vsModule, "main")
         .SetStage(nxt::ShaderStage::Fragment, fsModule, "main")
+        .SetIndexFormat(nxt::IndexFormat::Uint32)
         .SetInputState(inputState)
         .GetResult();
 }
@@ -96,7 +97,7 @@ void frame() {
         .BeginRenderSubpass()
             .SetRenderPipeline(pipeline)
             .SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets)
-            .SetIndexBuffer(indexBuffer, 0, nxt::IndexFormat::Uint32)
+            .SetIndexBuffer(indexBuffer, 0)
             .DrawElements(3, 1, 0, 0)
         .EndRenderSubpass()
         .EndRenderPass()

examples/HelloTriangle.cpp

@@ -129,6 +129,7 @@ void init() {
         .SetLayout(pl)
         .SetStage(nxt::ShaderStage::Vertex, vsModule, "main")
         .SetStage(nxt::ShaderStage::Fragment, fsModule, "main")
+        .SetIndexFormat(nxt::IndexFormat::Uint32)
         .SetInputState(inputState)
         .GetResult();
 
@@ -159,7 +160,7 @@ void frame() {
             .SetRenderPipeline(pipeline)
             .SetBindGroup(0, bindGroup)
             .SetVertexBuffers(0, 1, &vertexBuffer, vertexBufferOffsets)
-            .SetIndexBuffer(indexBuffer, 0, nxt::IndexFormat::Uint32)
+            .SetIndexBuffer(indexBuffer, 0)
             .DrawElements(3, 1, 0, 0)
         .EndRenderSubpass()
         .EndRenderPass()

examples/glTFViewer/glTFViewer.cpp

@@ -295,6 +295,7 @@ namespace {
             .SetLayout(pipelineLayout)
             .SetStage(nxt::ShaderStage::Vertex, oVSModule, "main")
             .SetStage(nxt::ShaderStage::Fragment, oFSModule, "main")
+            .SetIndexFormat(nxt::IndexFormat::Uint16)
             .SetInputState(inputState)
             .SetDepthStencilState(depthStencilState)
             .GetResult();
@@ -544,7 +545,7 @@ namespace {
                     continue;
                 }
                 const auto& oIndicesBuffer = buffers.at(iIndices.bufferView);
-                cmd.SetIndexBuffer(oIndicesBuffer, static_cast<uint32_t>(iIndices.byteOffset), nxt::IndexFormat::Uint16);
+                cmd.SetIndexBuffer(oIndicesBuffer, static_cast<uint32_t>(iIndices.byteOffset));
                 cmd.DrawElements(static_cast<uint32_t>(iIndices.count), 1, 0, 0);
             } else {
                 // DrawArrays

next.json

@@ -457,8 +457,7 @@
                 "name": "set index buffer",
                 "args": [
                     {"name": "buffer", "type": "buffer"},
-                    {"name": "offset", "type": "uint32_t"},
+                    {"name": "offset", "type": "uint32_t"}
-                    {"name": "format", "type": "index format"}
                 ]
             },
             {
@@ -939,6 +938,12 @@
                     {"name": "depth stencil state", "type": "depth stencil state"}
                 ]
             },
+            {
+                "name": "set index format",
+                "args": [
+                    {"name": "format", "type": "index format"}
+                ]
+            },
             {
                 "name": "set input state",
                 "args": [

src/backend/CommandBuffer.cpp

@@ -820,14 +820,13 @@ namespace backend {
         cmd->group = group;
     }
 
-    void CommandBufferBuilder::SetIndexBuffer(BufferBase* buffer, uint32_t offset, nxt::IndexFormat format) {
+    void CommandBufferBuilder::SetIndexBuffer(BufferBase* buffer, uint32_t offset) {
         // TODO(kainino@chromium.org): validation
 
         SetIndexBufferCmd* cmd = allocator.Allocate<SetIndexBufferCmd>(Command::SetIndexBuffer);
         new(cmd) SetIndexBufferCmd;
         cmd->buffer = buffer;
         cmd->offset = offset;
-        cmd->format = format;
     }
 
     void CommandBufferBuilder::SetVertexBuffers(uint32_t startSlot, uint32_t count, BufferBase* const* buffers, uint32_t const* offsets){

src/backend/CommandBuffer.h

@@ -83,7 +83,7 @@ namespace backend {
             void SetStencilReference(uint32_t reference);
             void SetBlendColor(float r, float g, float b, float a);
             void SetBindGroup(uint32_t groupIndex, BindGroupBase* group);
-            void SetIndexBuffer(BufferBase* buffer, uint32_t offset, nxt::IndexFormat format);
+            void SetIndexBuffer(BufferBase* buffer, uint32_t offset);
 
             template<typename T>
             void SetVertexBuffers(uint32_t startSlot, uint32_t count, T* const* buffers, uint32_t const* offsets) {

src/backend/Commands.h

@@ -152,7 +152,6 @@ namespace backend {
     struct SetIndexBufferCmd {
         Ref<BufferBase> buffer;
         uint32_t offset;
-        nxt::IndexFormat format;
     };
 
     struct SetVertexBuffersCmd {

src/backend/RenderPipeline.cpp

@@ -28,6 +28,7 @@ namespace backend {
     RenderPipelineBase::RenderPipelineBase(RenderPipelineBuilder* builder)
         : PipelineBase(builder),
           depthStencilState(std::move(builder->depthStencilState)),
+          indexFormat(builder->indexFormat),
           inputState(std::move(builder->inputState)),
           primitiveTopology(builder->primitiveTopology),
           blendStates(builder->blendStates),
@@ -55,6 +56,10 @@ namespace backend {
         return depthStencilState.Get();
     }
 
+    nxt::IndexFormat RenderPipelineBase::GetIndexFormat() const {
+        return indexFormat;
+    }
+
     InputStateBase* RenderPipelineBase::GetInputState() {
         return inputState.Get();
     }
@@ -122,6 +127,10 @@ namespace backend {
         this->depthStencilState = depthStencilState;
     }
 
+    void RenderPipelineBuilder::SetIndexFormat(nxt::IndexFormat format) {
+        this->indexFormat = format;
+    }
+
     void RenderPipelineBuilder::SetInputState(InputStateBase* inputState) {
         this->inputState = inputState;
     }

src/backend/RenderPipeline.h

@@ -30,6 +30,7 @@ namespace backend {
 
             BlendStateBase* GetBlendState(uint32_t attachmentSlot);
             DepthStencilStateBase* GetDepthStencilState();
+            nxt::IndexFormat GetIndexFormat() const;
             InputStateBase* GetInputState();
             nxt::PrimitiveTopology GetPrimitiveTopology() const;
             RenderPassBase* GetRenderPass();
@@ -37,6 +38,7 @@ namespace backend {
 
         private:
             Ref<DepthStencilStateBase> depthStencilState;
+            nxt::IndexFormat indexFormat;
             Ref<InputStateBase> inputState;
             nxt::PrimitiveTopology primitiveTopology;
             std::array<Ref<BlendStateBase>, kMaxColorAttachments> blendStates;
@@ -52,6 +54,7 @@ namespace backend {
             void SetColorAttachmentBlendState(uint32_t attachmentSlot, BlendStateBase* blendState);
             void SetDepthStencilState(DepthStencilStateBase* depthStencilState);
             void SetPrimitiveTopology(nxt::PrimitiveTopology primitiveTopology);
+            void SetIndexFormat(nxt::IndexFormat format);
             void SetInputState(InputStateBase* inputState);
             void SetSubpass(RenderPassBase* renderPass, uint32_t subpass);
 
@@ -64,6 +67,7 @@ namespace backend {
             Ref<InputStateBase> inputState;
             // TODO(enga@google.com): Remove default when we validate that all required properties are set
             nxt::PrimitiveTopology primitiveTopology = nxt::PrimitiveTopology::TriangleList;
+            nxt::IndexFormat indexFormat = nxt::IndexFormat::Uint32;
             std::bitset<kMaxColorAttachments> blendStatesSet;
             std::array<Ref<BlendStateBase>, kMaxColorAttachments> blendStates;
             Ref<RenderPassBase> renderPass;

src/backend/d3d12/CommandBufferD3D12.cpp

@@ -560,7 +560,10 @@ namespace d3d12 {
                         D3D12_INDEX_BUFFER_VIEW bufferView;
                         bufferView.BufferLocation = buffer->GetVA() + cmd->offset;
                         bufferView.SizeInBytes = buffer->GetSize() - cmd->offset;
-                        bufferView.Format = DXGIIndexFormat(cmd->format);
+                        //TODO(cwallez@chromium.org): Make index buffers lazily applied, right now
+                        //this will break if the pipeline is changed for one with a different index
+                        //format after SetIndexBuffer
+                        bufferView.Format = DXGIIndexFormat(lastRenderPipeline->GetIndexFormat());
 
                         commandList->IASetIndexBuffer(&bufferView);
                     }

src/backend/metal/CommandBufferMTL.mm

@@ -29,15 +29,6 @@ namespace backend {
 namespace metal {
 
     namespace {
-        MTLIndexType IndexFormatType(nxt::IndexFormat format) {
-            switch (format) {
-                case nxt::IndexFormat::Uint16:
-                    return MTLIndexTypeUInt16;
-                case nxt::IndexFormat::Uint32:
-                    return MTLIndexTypeUInt32;
-            }
-        }
-
         struct CurrentEncoders {
             Device* device;
 
@@ -172,7 +163,6 @@ namespace metal {
         RenderPipeline* lastRenderPipeline = nullptr;
         id<MTLBuffer> indexBuffer = nil;
         uint32_t indexBufferOffset = 0;
-        MTLIndexType indexType = MTLIndexTypeUInt32;
 
         CurrentEncoders encoders;
         encoders.device = device;
@@ -333,7 +323,7 @@ namespace metal {
                         [encoders.render
                             drawIndexedPrimitives:lastRenderPipeline->GetMTLPrimitiveTopology()
                             indexCount:draw->indexCount
-                            indexType:indexType
+                            indexType:lastRenderPipeline->GetMTLIndexType()
                             indexBuffer:indexBuffer
                             indexBufferOffset:indexBufferOffset
                             instanceCount:draw->instanceCount
@@ -564,7 +554,6 @@ namespace metal {
                         auto b = ToBackend(cmd->buffer.Get());
                         indexBuffer = b->GetMTLBuffer();
                         indexBufferOffset = cmd->offset;
-                        indexType = IndexFormatType(cmd->format);
                     }
                     break;
 

src/backend/metal/RenderPipelineMTL.h

@@ -27,11 +27,13 @@ namespace metal {
             RenderPipeline(RenderPipelineBuilder* builder);
             ~RenderPipeline();
 
+            MTLIndexType GetMTLIndexType() const;
             MTLPrimitiveType GetMTLPrimitiveTopology() const;
 
             void Encode(id<MTLRenderCommandEncoder> encoder);
 
         private:
+            MTLIndexType mtlIndexType;
             MTLPrimitiveType mtlPrimitiveTopology;
             id<MTLRenderPipelineState> mtlRenderPipelineState = nil;
     };

src/backend/metal/RenderPipelineMTL.mm

@@ -53,10 +53,21 @@ namespace metal {
                     return MTLPrimitiveTopologyClassTriangle;
             }
         }
+
+        MTLIndexType MTLIndexFormat(nxt::IndexFormat format) {
+            switch (format) {
+                case nxt::IndexFormat::Uint16:
+                    return MTLIndexTypeUInt16;
+                case nxt::IndexFormat::Uint32:
+                    return MTLIndexTypeUInt32;
+            }
+        }
     }
 
     RenderPipeline::RenderPipeline(RenderPipelineBuilder* builder)
-        : RenderPipelineBase(builder), mtlPrimitiveTopology(MTLPrimitiveTopology(GetPrimitiveTopology())) {
+        : RenderPipelineBase(builder),
+          mtlIndexType(MTLIndexFormat(GetIndexFormat())),
+          mtlPrimitiveTopology(MTLPrimitiveTopology(GetPrimitiveTopology())) {
 
         auto mtlDevice = ToBackend(builder->GetDevice())->GetMTLDevice();
 
@@ -121,6 +132,10 @@ namespace metal {
         [mtlRenderPipelineState release];
     }
 
+    MTLIndexType RenderPipeline::GetMTLIndexType() const {
+        return mtlIndexType;
+    }
+
     MTLPrimitiveType RenderPipeline::GetMTLPrimitiveTopology() const {
         return mtlPrimitiveTopology;
     }

src/backend/opengl/CommandBufferGL.cpp

@@ -129,7 +129,6 @@ namespace opengl {
         PipelineGL* lastGLPipeline = nullptr;
         RenderPipeline* lastRenderPipeline = nullptr;
         uint32_t indexBufferOffset = 0;
-        nxt::IndexFormat indexBufferFormat = nxt::IndexFormat::Uint16;
 
         PersistentPipelineState persistentPipelineState;
         persistentPipelineState.SetDefaultState();
@@ -380,8 +379,9 @@ namespace opengl {
                         DrawElementsCmd* draw = commands.NextCommand<DrawElementsCmd>();
                         pushConstants.Apply(lastPipeline, lastGLPipeline);
 
-                        size_t formatSize = IndexFormatSize(indexBufferFormat);
+                        nxt::IndexFormat indexFormat = lastRenderPipeline->GetIndexFormat();
-                        GLenum formatType = IndexFormatType(indexBufferFormat);
+                        size_t formatSize = IndexFormatSize(indexFormat);
+                        GLenum formatType = IndexFormatType(indexFormat);
 
                         if (draw->firstInstance > 0) {
                             glDrawElementsInstancedBaseInstance(lastRenderPipeline->GetGLPrimitiveTopology(),
@@ -530,7 +530,6 @@ namespace opengl {
 
                         GLuint buffer = ToBackend(cmd->buffer.Get())->GetHandle();
                         indexBufferOffset = cmd->offset;
-                        indexBufferFormat = cmd->format;
                         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffer);
                     }
                     break;