Needs cleaning: Move descriptor set binding to bind pipeline, caching them if a render pass is not begun

filament/backend/src/webgpu/WebGPUDriver.cpp

@@ -354,6 +354,17 @@ void WebGPUDriver::destroyProgram(Handle<HwProgram> ph) {
 }
 
 void WebGPUDriver::destroyRenderTarget(Handle<HwRenderTarget> rth) {
+    if (rth) {
+        WGPURenderTarget* rt = handleCast<WGPURenderTarget>(rth);
+        if (rt == mDefaultRenderTarget) {
+            mDefaultRenderTarget = nullptr;
+        }
+        // WGPURenderTarget destructor is trivial.
+        // The HwTexture handles stored within WGPURenderTarget (via MRT, TargetBufferInfo)
+        // are not owned by WGPURenderTarget, so they are not destroyed here.
+        // They are destroyed via WebGPUDriver::destroyTexture.
+        destructHandle<WGPURenderTarget>(rth);
+    }
 }
 
 void WebGPUDriver::destroySwapChain(Handle<HwSwapChain> sch) {
@@ -571,7 +582,6 @@ void WebGPUDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph, Handle<
 void WebGPUDriver::createProgramR(Handle<HwProgram> ph, Program&& program) {
     constructHandle<WGPUProgram>(ph, mDevice, program);
 }
-
 void WebGPUDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, int) {
     assert_invariant(!mDefaultRenderTarget);
     mDefaultRenderTarget = constructHandle<WGPURenderTarget>(rth);
@@ -580,7 +590,21 @@ void WebGPUDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, int) {
 
 void WebGPUDriver::createRenderTargetR(Handle<HwRenderTarget> rth, TargetBufferFlags targets,
         uint32_t width, uint32_t height, uint8_t samples, uint8_t layerCount, MRT color,
-        TargetBufferInfo depth, TargetBufferInfo stencil) {}
+        TargetBufferInfo depth, TargetBufferInfo stencil) {
+    // The `targets` flags indicate which of the `color`, `depth`, `stencil` TargetBufferInfo
+    // are actually active for this render target.
+    // We'll pass all TargetBufferInfo to WGPURenderTarget; it will use them if their handles are valid.
+
+    // Ensure that textures intended for use as attachments were created with
+    // wgpu::TextureUsage::RenderAttachment. This check should ideally be in createTextureR
+    // or validated here if possible.
+
+    // The `layerCount` parameter might be for creating array textures that this RT targets.
+    // Individual attachments (color[i].layer, depth.layer, stencil.layer) specify which layer
+    // of an array texture to bind. For now, we assume textures are pre-configured.
+
+    constructHandle<WGPURenderTarget>(rth, width, height, samples, color, depth, stencil);
+}
 
 void WebGPUDriver::createFenceR(Handle<HwFence> fh, int) {}
 
@@ -845,35 +869,74 @@ void WebGPUDriver::compilePrograms(CompilerPriorityQueue priority,
 
 void WebGPUDriver::beginRenderPass(Handle<HwRenderTarget> rth, RenderPassParams const& params) {
     assert_invariant(mCommandEncoder);
-
     auto* renderTarget = handleCast<WGPURenderTarget>(rth);
-    // if (renderTarget == mDefaultRenderTarget) {
-    //     FWGPU_LOGW << "Default render target"
-    //                << utils::io::endl;
-    // } else {
-    //     FWGPU_LOGW << "Non Default render target"
-    //                << utils::io::endl;
-    // }
-    wgpu::RenderPassDescriptor renderPassDescriptor;
-    wgpu::RenderPassDepthStencilAttachment depthStencilAttachment{
-        .view = mSwapChain->getDepthTextureView(),
-        .depthLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::DEPTH),
-        .depthStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::DEPTH),
-        .depthClearValue = static_cast<float>(params.clearDepth),
-        .depthReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) > 0,
-        .stencilLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::STENCIL),
-        .stencilStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::STENCIL),
-        .stencilClearValue = params.clearStencil,
-        .stencilReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_STENCIL) > 0
-    };
-    renderTarget->setUpRenderPassAttachments(renderPassDescriptor, mTextureView, params);
-    renderPassDescriptor.depthStencilAttachment = &depthStencilAttachment;
 
-    assert_invariant(mTextureView);
+    wgpu::RenderPassDescriptor renderPassDescriptor{};
+    wgpu::TextureView defaultColorView = nullptr;
+    wgpu::TextureView defaultDepthStencilView = nullptr;
+
+    std::array<wgpu::TextureView, MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT> customColorViews{};
+    uint32_t customColorViewCount = 0;
+    wgpu::TextureView customDepthView = nullptr;
+    wgpu::TextureView customStencilView = nullptr;
+
+    if (renderTarget->isDefaultRenderTarget()) {
+        assert_invariant(mSwapChain && mTextureView);
+        defaultColorView = mTextureView;
+        defaultDepthStencilView = mSwapChain->getDepthTextureView();
+    } else {
+        // Resolve views for custom render target
+        const auto& colorInfos = renderTarget->getColorAttachmentInfos();
+        for (int i = 0; i < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT; ++i) {
+            if (colorInfos[i].handle) {
+                auto* hwTexture = handleCast<WGPUTexture>(colorInfos[i].handle);
+                if (hwTexture) {
+                    // TODO: Consider colorInfos[i].level and colorInfos[i].layer for view creation
+                    // if WGPUTexture::getTexView() isn't sufficient or needs parameters.
+                    customColorViews[customColorViewCount++] = hwTexture->getTexView();
+                }
+            }
+        }
+
+        const auto& depthInfo = renderTarget->getDepthAttachmentInfo();
+        if (depthInfo.handle) {
+            auto* hwTexture = handleCast<WGPUTexture>(depthInfo.handle);
+            if (hwTexture) {
+                customDepthView = hwTexture->getTexView();
+            }
+        }
+
+        const auto& stencilInfo = renderTarget->getStencilAttachmentInfo();
+        if (stencilInfo.handle) {
+            // If depth and stencil use the same texture handle, this will re-cast but that's fine.
+            auto* hwTexture = handleCast<WGPUTexture>(stencilInfo.handle);
+            if (hwTexture) {
+                customStencilView = hwTexture->getTexView();
+            }
+        }
+    }
+
+    renderTarget->setUpRenderPassAttachments(renderPassDescriptor,
+            params,
+            defaultColorView,
+            defaultDepthStencilView,
+            customColorViews.data(),
+            customColorViewCount,
+            customDepthView,
+            customStencilView);
 
     mRenderPassEncoder = mCommandEncoder.BeginRenderPass(&renderPassDescriptor);
-    mRenderPassEncoder.SetViewport(params.viewport.left, params.viewport.bottom,
-            params.viewport.width, params.viewport.height, params.depthRange.near, params.depthRange.far);
+    // Ensure viewport dimensions are positive
+    uint32_t viewportWidth = params.viewport.width > 0 ? params.viewport.width : 1;
+    uint32_t viewportHeight = params.viewport.height > 0 ? params.viewport.height : 1;
+
+    mRenderPassEncoder.SetViewport(
+            static_cast<float>(params.viewport.left),
+            static_cast<float>(params.viewport.bottom),
+            static_cast<float>(viewportWidth),
+            static_cast<float>(viewportHeight),
+            params.depthRange.near,
+            params.depthRange.far);
 }
 
 void WebGPUDriver::endRenderPass(int /* dummy */) {
@@ -966,10 +1029,20 @@ void WebGPUDriver::bindPipeline(PipelineState const& pipelineState) {
     // VulkanPipelineCache to handle this, may be missing nuance
     static auto pipleineStateHasher = utils::hash::MurmurHashFn<filament::backend::PipelineState>();
     auto hash = pipleineStateHasher(pipelineState);
-    if(mPipelineMap.find(hash) != mPipelineMap.end()){
+    if(mPipelineMap.find(hash) != mPipelineMap.end()) {
         mRenderPassEncoder.SetPipeline(mPipelineMap[hash]);
         return;
     }
+    for (size_t index = 0; index < MAX_DESCRIPTOR_SET_COUNT; ++index) {
+        auto& entry = currentDescriptorSets[index];
+        if (entry.bg != nullptr) {
+            mRenderPassEncoder.SetBindGroup(index, entry.bg, entry.dynamicOffsetCount,
+                    entry.offsets.data());
+            entry.bg = nullptr;
+            entry.dynamicOffsetCount = 0;
+            entry.offsets.clear();
+        }
+    }
     const auto* program = handleCast<WGPUProgram>(pipelineState.program);
     assert_invariant(program);
     assert_invariant(program->computeShaderModule == nullptr &&
@@ -1012,14 +1085,20 @@ void WebGPUDriver::bindPipeline(PipelineState const& pipelineState) {
 
 void WebGPUDriver::bindRenderPrimitive(Handle<HwRenderPrimitive> rph) {
     auto* renderPrimitive = handleCast<WGPURenderPrimitive>(rph);
+    auto* vbi = handleCast<WGPUVertexBufferInfo>(renderPrimitive->vertexBuffer->vbih);
 
-    // This *must* match the WGPUVertexBufferInfo that was bound in bindPipeline(). But we want
-    // to allow to call this before bindPipeline(), so the validation can only happen in draw()
-    auto vbi = handleCast<WGPUVertexBufferInfo>(renderPrimitive->vertexBuffer->vbih);
-    assert_invariant(
-            vbi->getVertexBufferLayoutSize() == renderPrimitive->vertexBuffer->buffers.size());
-    for (uint32_t i = 0; i < vbi->getVertexBufferLayoutSize(); i++) {
-        mRenderPassEncoder.SetVertexBuffer(i, renderPrimitive->vertexBuffer->buffers[i]);
+    // Loop over the WebGPU vertex buffer slots defined by the VertexBufferInfo.
+    // For each WebGPU slot, find the corresponding Filament buffer that supplies the data.
+    for (uint32_t webGPUSlot = 0; webGPUSlot < vbi->getWebGPULayoutCount(); ++webGPUSlot) {
+        uint8_t filamentBufferIndex = vbi->getFilamentBufferIndexForSlot(webGPUSlot);
+
+        // Ensure the Filament buffer index is valid for the vertexBuffer's internal storage.
+        // This check assumes renderPrimitive->vertexBuffer->buffers is sized by the
+        // original Filament buffer count.
+        assert_invariant(filamentBufferIndex < renderPrimitive->vertexBuffer->buffers.size());
+
+        mRenderPassEncoder.SetVertexBuffer(webGPUSlot,
+                renderPrimitive->vertexBuffer->buffers[filamentBufferIndex]);
     }
 
     mRenderPassEncoder.SetIndexBuffer(renderPrimitive->indexBuffer->getBuffer(),
@@ -1093,9 +1172,12 @@ void WebGPUDriver::bindDescriptorSet(Handle<HwDescriptorSet> dsh,
         backend::descriptor_set_t setIndex, backend::DescriptorSetOffsetArray&& offsets) {
     const auto bindGroup = handleCast<WebGPUDescriptorSet>(dsh);
     const auto wbg = bindGroup->lockAndReturn(mDevice);
-    assert_invariant(mRenderPassEncoder);
     const size_t dynamicOffsetCount = bindGroup->countEntitiesWithDynamicOffsets();
-    mRenderPassEncoder.SetBindGroup(setIndex, wbg, dynamicOffsetCount, offsets.data());
+
+    if(mRenderPassEncoder){
+        mRenderPassEncoder.SetBindGroup(setIndex, wbg, dynamicOffsetCount, offsets.data());
+    }
+    currentDescriptorSets[setIndex] = {wbg, dynamicOffsetCount, std::move(offsets)};
 }
 
 void WebGPUDriver::setDebugTag(HandleBase::HandleId handleId, utils::CString tag) {

filament/backend/src/webgpu/WebGPUDriver.h

@@ -72,6 +72,12 @@ private:
     wgpu::CommandEncoder mCommandEncoder = nullptr;
     wgpu::TextureView mTextureView = nullptr;
     wgpu::RenderPassEncoder mRenderPassEncoder = nullptr;
+    struct bgInfo{
+        wgpu::BindGroup bg;
+        size_t dynamicOffsetCount;
+        backend::DescriptorSetOffsetArray offsets;
+    };
+    std::array<bgInfo, MAX_DESCRIPTOR_SET_COUNT> currentDescriptorSets = {};
     wgpu::CommandBuffer mCommandBuffer = nullptr;
     WGPURenderTarget* mDefaultRenderTarget = nullptr;
 

filament/backend/src/webgpu/WebGPUHandles.cpp

@@ -25,6 +25,7 @@
 
 #include <algorithm>
 #include <cstdint>
+#include <map>
 #include <utility>
 #include <vector>
 
@@ -196,43 +197,77 @@ void WGPUBufferBase::updateGPUBuffer(BufferDescriptor& bufferDescriptor, uint32_
         queue.WriteBuffer(buffer, byteOffset + legalSize, &mRemainderChunk, 4);
     }
 }
+
 WGPUVertexBufferInfo::WGPUVertexBufferInfo(uint8_t bufferCount, uint8_t attributeCount,
         AttributeArray const& attributes)
-    : HwVertexBufferInfo(bufferCount, attributeCount),
-      mVertexBufferLayout(bufferCount),
-      mAttributes(bufferCount) {
+    : HwVertexBufferInfo(bufferCount, attributeCount) { // Base class constructor
+
     assert_invariant(attributeCount > 0);
-    assert_invariant(bufferCount > 0);
+    // bufferCount is Filament's buffer count. The number of WebGPU slots might differ.
+
+    struct LayoutKey {
+        uint8_t filamentBufferIndex;
+        uint16_t stride;
+        bool operator<(const LayoutKey& other) const {
+            if (filamentBufferIndex != other.filamentBufferIndex) {
+                return filamentBufferIndex < other.filamentBufferIndex;
+            }
+            return stride < other.stride;
+        }
+    };
+    std::map<LayoutKey, uint32_t> layoutKeyToWebGPUSlot;
+    uint32_t nextWebGPUSlot = 0;
+
     for (uint32_t attribIndex = 0; attribIndex < attributes.size(); attribIndex++) {
         Attribute const& attrib = attributes[attribIndex];
-        // Ignore the attributes which are not bind to vertex buffers.
+        // Ignore attributes not bound to any vertex buffer.
         if (attrib.buffer == Attribute::BUFFER_UNUSED) {
             continue;
         }
 
-        assert_invariant(attrib.buffer < bufferCount);
+        assert_invariant(attrib.buffer < bufferCount); // Ensure Filament buffer index is valid
+
+        LayoutKey key = {attrib.buffer, attrib.stride};
+        uint32_t currentWebGPUSlot;
+
+        auto it = layoutKeyToWebGPUSlot.find(key);
+        if (it == layoutKeyToWebGPUSlot.end()) {
+            currentWebGPUSlot = nextWebGPUSlot++;
+            layoutKeyToWebGPUSlot[key] = currentWebGPUSlot;
+
+            mActualWebGPULayouts.emplace_back();
+            mActualWebGPULayouts.back().arrayStride = attrib.stride;
+            mActualWebGPULayouts.back().stepMode = wgpu::VertexStepMode::Vertex;
+            // .attributes and .attributeCount will be set later
+
+            mSlotMappings.emplace_back(SlotMapping{attrib.buffer});
+            mActualWebGPUAttributes.emplace_back(); // Add a new vector for this slot's attributes
+        } else {
+            currentWebGPUSlot = it->second;
+            // Sanity check: if we found an existing slot for this key, its stride should match.
+            assert_invariant(mActualWebGPULayouts[currentWebGPUSlot].arrayStride == attrib.stride);
+        }
+
         bool const isInteger = attrib.flags & Attribute::FLAG_INTEGER_TARGET;
         bool const isNormalized = attrib.flags & Attribute::FLAG_NORMALIZED;
         wgpu::VertexFormat vertexFormat = getVertexFormat(attrib.type, isNormalized, isInteger);
 
-        // Attributes are sequential per buffer
-        mAttributes[attrib.buffer].push_back({
+        mActualWebGPUAttributes[currentWebGPUSlot].push_back({
             .format = vertexFormat,
             .offset = attrib.offset,
-            .shaderLocation = attribIndex,
+            .shaderLocation = attribIndex, // Use original attribIndex as shaderLocation
         });
-
-        mVertexBufferLayout[attrib.buffer].stepMode = wgpu::VertexStepMode::Vertex;
-        if (mVertexBufferLayout[attrib.buffer].arrayStride == 0) {
-            mVertexBufferLayout[attrib.buffer].arrayStride = attrib.stride;
-        } else {
-            assert_invariant(mVertexBufferLayout[attrib.buffer].arrayStride == attrib.stride);
-        }
     }
 
-    for (uint32_t bufferIndex = 0; bufferIndex < bufferCount; bufferIndex++) {
-        mVertexBufferLayout[bufferIndex].attributeCount = mAttributes[bufferIndex].size();
-        mVertexBufferLayout[bufferIndex].attributes = mAttributes[bufferIndex].data();
+    // Finalize attribute pointers and counts in mActualWebGPULayouts
+    for (uint32_t slot = 0; slot < mActualWebGPULayouts.size(); ++slot) {
+        if (!mActualWebGPUAttributes[slot].empty()) {
+            mActualWebGPULayouts[slot].attributeCount = mActualWebGPUAttributes[slot].size();
+            mActualWebGPULayouts[slot].attributes = mActualWebGPUAttributes[slot].data();
+        } else {
+            mActualWebGPULayouts[slot].attributeCount = 0;
+            mActualWebGPULayouts[slot].attributes = nullptr;
+        }
     }
 }
 
@@ -923,58 +958,147 @@ wgpu::TextureView WGPUTexture::makeTextureView(const uint8_t& baseLevel, const u
     return textureView;
 }
 
-WGPURenderTarget::Attachment WGPURenderTarget::getDrawColorAttachment(size_t index) {
-    assert_invariant( index < MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT);
-    auto result = color[index];
-    if (index == 0 && defaultRenderTarget) {
-
-    }
-
-    return result;
+WGPURenderTarget::WGPURenderTarget(uint32_t width, uint32_t height, uint8_t samples,
+        const MRT& colorAttachmentsMRT,
+        const Attachment& depthAttachmentInfo,
+        const Attachment& stencilAttachmentInfo)
+    : HwRenderTarget(width, height),
+      defaultRenderTarget(false),
+      samples(samples),
+      mColorAttachments(colorAttachmentsMRT),
+      mDepthAttachment(depthAttachmentInfo),
+      mStencilAttachment(stencilAttachmentInfo) {
+    mColorAttachmentDescriptors.reserve(MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT);
 }
 
+// Static helper to map MRT index to TargetBufferFlags
+TargetBufferFlags WGPURenderTarget::getTargetBufferFlagsAt(int mrtIndex) {
+    if (mrtIndex < 0 || mrtIndex >= MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT) {
+        return TargetBufferFlags::NONE;
+    }
+    // This mapping assumes TargetBufferFlags::COLOR_0, COLOR_1 etc. are contiguous
+    return static_cast<TargetBufferFlags>(
+            static_cast<uint32_t>(TargetBufferFlags::COLOR0) << mrtIndex);
+}
+
+// Corrected getLoadOperation
 wgpu::LoadOp WGPURenderTarget::getLoadOperation(RenderPassParams const& params,
-                                             TargetBufferFlags buffer) {
-    auto clearFlags = params.flags.clear;
-    auto discardStartFlags = params.flags.discardStart;
-    if (any(clearFlags & buffer)) {
-        return wgpu::LoadOp::Clear;
-    } else if (any(discardStartFlags & buffer)) {
+                                                TargetBufferFlags bufferToOperateOn) {
+    if (any(params.flags.clear & bufferToOperateOn)) {
         return wgpu::LoadOp::Clear;
     }
+    if (any(params.flags.discardStart & bufferToOperateOn)) {
+        return wgpu::LoadOp::Clear; // Or wgpu::LoadOp::Undefined if clear is not desired on discard
+    }
     return wgpu::LoadOp::Load;
 }
 
+// Corrected getStoreOperation
 wgpu::StoreOp WGPURenderTarget::getStoreOperation(RenderPassParams const& params,
-                                               TargetBufferFlags buffer) {
-    const auto discardEndFlags = params.flags.discardEnd;
-    if (any(discardEndFlags & buffer)) {
+                                                  TargetBufferFlags bufferToOperateOn) {
+    if (any(params.flags.discardEnd & bufferToOperateOn)) {
         return wgpu::StoreOp::Discard;
     }
     return wgpu::StoreOp::Store;
 }
-void WGPURenderTarget::setUpRenderPassAttachments(wgpu::RenderPassDescriptor& descriptor,
-        wgpu::TextureView const& textureView, RenderPassParams const& params) {
-    // auto discardFlags = params.flags.discardEnd;
-    // (void) discardFlags;
-    // std::vector<wgpu::RenderPassColorAttachment> colorAttachments;
-    colorAttachments.clear();
-    for (size_t i = 0; i < 1/*MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT*/; i++) {
-        // auto attachment = getDrawColorAttachment(i);
-        // if (attachment) {
-            wgpu::RenderPassColorAttachment colorAttachment;
-            colorAttachment.view = textureView;
-            colorAttachment.loadOp  = getLoadOperation(params, getTargetBufferFlagsAt(i));
-            colorAttachment.storeOp = getStoreOperation(params, getTargetBufferFlagsAt(i));
-            colorAttachment.clearValue = { params.clearColor.r, params.clearColor.g, params.clearColor.b, params.clearColor.a };
-            colorAttachments.emplace_back(colorAttachment);
-        // }
+
+void WGPURenderTarget::setUpRenderPassAttachments(
+        wgpu::RenderPassDescriptor& descriptor,
+        RenderPassParams const& params,
+        wgpu::TextureView const& defaultColorTextureView,
+        wgpu::TextureView const& defaultDepthStencilTextureView,
+        wgpu::TextureView const* customColorTextureViews,
+        uint32_t customColorTextureViewCount,
+        wgpu::TextureView const& customDepthTextureView,
+        wgpu::TextureView const& customStencilTextureView) {
+    mColorAttachmentDescriptors.clear();
+    mHasDepthStencilAttachment = false;
+
+    if (defaultRenderTarget) {
+        assert_invariant(defaultColorTextureView);
+        wgpu::RenderPassColorAttachment colorAttDesc{};
+        colorAttDesc.view = defaultColorTextureView;
+        colorAttDesc.resolveTarget = nullptr;
+        colorAttDesc.loadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::COLOR0);
+        colorAttDesc.storeOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::COLOR0);
+        colorAttDesc.clearValue = {params.clearColor.r, params.clearColor.g,
+                                   params.clearColor.b, params.clearColor.a};
+        mColorAttachmentDescriptors.push_back(colorAttDesc);
+
+        if (defaultDepthStencilTextureView) {
+            mDepthStencilAttachmentDescriptor = {
+                .view = defaultDepthStencilTextureView,
+                .depthLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::DEPTH),
+                .depthStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::DEPTH),
+                .depthClearValue = static_cast<float>(params.clearDepth),
+                .depthReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) > 0,
+                .stencilLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::STENCIL),
+                .stencilStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::STENCIL),
+                .stencilClearValue = params.clearStencil,
+                .stencilReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_STENCIL) > 0,
+            };
+            mHasDepthStencilAttachment = true;
+        }
+    } else { // Custom Render Target
+        for (uint32_t i = 0; i < customColorTextureViewCount; ++i) {
+            if (customColorTextureViews[i]) {
+                wgpu::RenderPassColorAttachment colorAttDesc{};
+                colorAttDesc.view = customColorTextureViews[i];
+                colorAttDesc.resolveTarget = nullptr; // TODO: MSAA resolve for custom RT
+                colorAttDesc.loadOp = WGPURenderTarget::getLoadOperation(params, getTargetBufferFlagsAt(i));
+                colorAttDesc.storeOp = WGPURenderTarget::getStoreOperation(params, getTargetBufferFlagsAt(i));
+                colorAttDesc.clearValue = {params.clearColor.r, params.clearColor.g,
+                                           params.clearColor.b, params.clearColor.a};
+                mColorAttachmentDescriptors.push_back(colorAttDesc);
+            }
+        }
+
+        wgpu::TextureView combinedDsView = customDepthTextureView ? customDepthTextureView : customStencilTextureView;
+
+        if (combinedDsView) {
+            mDepthStencilAttachmentDescriptor = {};
+            mDepthStencilAttachmentDescriptor.view = combinedDsView;
+
+            if (customDepthTextureView) {
+                mDepthStencilAttachmentDescriptor.depthLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::DEPTH);
+                mDepthStencilAttachmentDescriptor.depthStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::DEPTH);
+                mDepthStencilAttachmentDescriptor.depthClearValue = static_cast<float>(params.clearDepth);
+                mDepthStencilAttachmentDescriptor.depthReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_DEPTH) > 0;
+            } else {
+                mDepthStencilAttachmentDescriptor.depthLoadOp = wgpu::LoadOp::Undefined;
+                mDepthStencilAttachmentDescriptor.depthStoreOp = wgpu::StoreOp::Undefined;
+                mDepthStencilAttachmentDescriptor.depthReadOnly = true;
+            }
+
+            if (customStencilTextureView) {
+                mDepthStencilAttachmentDescriptor.stencilLoadOp = WGPURenderTarget::getLoadOperation(params, TargetBufferFlags::STENCIL);
+                mDepthStencilAttachmentDescriptor.stencilStoreOp = WGPURenderTarget::getStoreOperation(params, TargetBufferFlags::STENCIL);
+                mDepthStencilAttachmentDescriptor.stencilClearValue = params.clearStencil;
+                mDepthStencilAttachmentDescriptor.stencilReadOnly = (params.readOnlyDepthStencil & RenderPassParams::READONLY_STENCIL) > 0;
+            } else {
+                mDepthStencilAttachmentDescriptor.stencilLoadOp = wgpu::LoadOp::Undefined;
+                mDepthStencilAttachmentDescriptor.stencilStoreOp = wgpu::StoreOp::Undefined;
+                mDepthStencilAttachmentDescriptor.stencilReadOnly = true;
+            }
+            mHasDepthStencilAttachment = true;
+        }
     }
-    descriptor.colorAttachments = colorAttachments.data();
-    descriptor.colorAttachmentCount = colorAttachments.size();
-    descriptor.depthStencilAttachment = nullptr;
-    descriptor.timestampWrites = nullptr;
+
+    descriptor.colorAttachmentCount = mColorAttachmentDescriptors.size();
+    descriptor.colorAttachments = mColorAttachmentDescriptors.data();
+    descriptor.depthStencilAttachment = mHasDepthStencilAttachment ? &mDepthStencilAttachmentDescriptor : nullptr;
+    // descriptor.sampleCount was removed from the core spec. If your webgpu.h still has it,
+    // and your Dawn version expects it, you might need to set it here based on this->samples.
+    // e.g., descriptor.sampleCount = this->samples;
 }
 
+math::uint2 WGPURenderTarget::getAttachmentSize() const noexcept {
+    if (!defaultRenderTarget) {
+        return {width, height};
+    }
+    // For default RT, size is dynamic and usually obtained from the swapchain.
+    // The caller (WebGPUDriver::beginRenderPass) should know the current swapchain size.
+    return {0,0};
+}
 
 }// namespace filament::backend

filament/backend/src/webgpu/WebGPUHandles.h

@@ -52,30 +52,40 @@ class WGPUVertexBufferInfo : public HwVertexBufferInfo {
 public:
     WGPUVertexBufferInfo(uint8_t bufferCount, uint8_t attributeCount,
             AttributeArray const& attributes);
-    inline  wgpu::VertexBufferLayout const* getVertexBufferLayout() const {
-        return mVertexBufferLayout.data();
+
+    // Returns the WebGPU native vertex buffer layouts
+    inline wgpu::VertexBufferLayout const* getWebGPULayouts() const {
+        return mActualWebGPULayouts.data();
     }
 
-    inline uint32_t getVertexBufferLayoutSize() const {
-        return mVertexBufferLayout.size();
+    // Returns the count of WebGPU native vertex buffer layouts
+    inline uint32_t getWebGPULayoutCount() const {
+        return mActualWebGPULayouts.size();
     }
 
-    inline wgpu::VertexAttribute const* getVertexAttributeForIndex(uint32_t index) const {
-        assert_invariant(index < mAttributes.size());
-        return mAttributes[index].data();
-    }
-
-    inline uint32_t getVertexAttributeSize(uint32_t index) const {
-        assert_invariant(index < mAttributes.size());
-        return mAttributes[index].size();
+    // Returns the Filament buffer index for a given WebGPU layout slot
+    inline uint8_t getFilamentBufferIndexForSlot(uint32_t webgpuSlotIndex) const {
+        assert_invariant(webgpuSlotIndex < mSlotMappings.size());
+        return mSlotMappings[webgpuSlotIndex].filamentBufferIndex;
     }
 
 private:
-    // TODO: can we do better in terms on heap management.
-    std::vector<wgpu::VertexBufferLayout> mVertexBufferLayout{};
-    std::vector<std::vector<wgpu::VertexAttribute>> mAttributes{};
-};
+    // Stores the final WebGPU vertex buffer layouts
+    std::vector<wgpu::VertexBufferLayout> mActualWebGPULayouts;
+    // Stores attributes per WebGPU layout, parallel to mActualWebGPULayouts.
+    // Each wgpu::VertexBufferLayout in mActualWebGPULayouts will point to its attributes here.
+    std::vector<std::vector<wgpu::VertexAttribute>> mActualWebGPUAttributes;
 
+    struct SlotMapping {
+        uint8_t filamentBufferIndex; // Original Filament buffer index for this WebGPU slot
+    };
+    // Maps a WebGPU slot index to its original Filament buffer index
+    std::vector<SlotMapping> mSlotMappings;
+
+    // Remove or comment out old members if they were similarly named:
+    // std::vector<wgpu::VertexBufferLayout> mVertexBufferLayout {}; // OLD
+    // std::vector<std::vector<wgpu::VertexAttribute>> mAttributes {}; // OLD
+};
 struct WGPUVertexBuffer : public HwVertexBuffer {
     WGPUVertexBuffer(wgpu::Device const &device, uint32_t vertexCount, uint32_t bufferCount,
                      Handle<HwVertexBufferInfo> vbih);
@@ -197,57 +207,66 @@ struct WGPURenderPrimitive : public HwRenderPrimitive {
     WGPUIndexBuffer* indexBuffer = nullptr;
 };
 
+
+
 class WGPURenderTarget : public HwRenderTarget {
 public:
-    class Attachment {
-    public:
-        friend class WGPURenderTarget;
-
-        Attachment() = default;
-        Attachment(WGPUTexture* gpuTexture, uint8_t level = 0, uint16_t layer = 0)
-            : level(level),
-              layer(layer),
-              texture(gpuTexture->getTexture()),
-              mWGPUTexture(gpuTexture) {}
-        operator bool() const {
-            return mWGPUTexture != nullptr;
-        }
-
-        uint8_t level = 0;
-        uint16_t layer = 0;
-
-    private:
-        wgpu::Texture texture = nullptr;
-        WGPUTexture* mWGPUTexture = nullptr;
-    };
+    using Attachment = TargetBufferInfo; // Using TargetBufferInfo directly for attachments
 
     WGPURenderTarget(uint32_t width, uint32_t height, uint8_t samples,
-            Attachment colorAttachments[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT]);
+            const MRT& colorAttachments,
+            const Attachment& depthAttachment,
+            const Attachment& stencilAttachment);
+
+    // Default constructor for the default render target
     WGPURenderTarget()
         : HwRenderTarget(0, 0),
-          defaultRenderTarget(true) {}
+          defaultRenderTarget(true),
+          samples(1) {}
 
-    void setUpRenderPassAttachments(wgpu::RenderPassDescriptor& descriptor,
-            wgpu::TextureView const& textureView, RenderPassParams const& params);
+    // Updated signature: takes resolved views for custom RTs, and default views for default RT
+    void setUpRenderPassAttachments(
+            wgpu::RenderPassDescriptor& descriptor,
+            RenderPassParams const& params,
+            // For default render target:
+            wgpu::TextureView const& defaultColorTextureView,
+            wgpu::TextureView const& defaultDepthStencilTextureView,
+            // For custom render targets:
+            wgpu::TextureView const* customColorTextureViews, // Array of views
+            uint32_t customColorTextureViewCount,
+            wgpu::TextureView const& customDepthTextureView,
+            wgpu::TextureView const& customStencilTextureView);
 
-    math::uint2 getAttachmentSize() noexcept;
+
+    math::uint2 getAttachmentSize() const noexcept;
 
     bool isDefaultRenderTarget() const { return defaultRenderTarget; }
     uint8_t getSamples() const { return samples; }
 
-    Attachment getDrawColorAttachment(size_t index);
-    Attachment getReadColorAttachment(size_t index);
+    // Accessors for the driver to get stored attachment info
+    const MRT& getColorAttachmentInfos() const { return mColorAttachments; }
+    const Attachment& getDepthAttachmentInfo() const { return mDepthAttachment; }
+    const Attachment& getStencilAttachmentInfo() const { return mStencilAttachment; }
 
+    // Static helpers for load/store operations
     static wgpu::LoadOp getLoadOperation(const RenderPassParams& params, TargetBufferFlags buffer);
     static wgpu::StoreOp getStoreOperation(const RenderPassParams& params, TargetBufferFlags buffer);
+
 private:
+    // Helper to map MRT index to TargetBufferFlags
+    static TargetBufferFlags getTargetBufferFlagsAt(int mrtIndex);
+
     bool defaultRenderTarget = false;
     uint8_t samples = 1;
 
-    Attachment color[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT] = {};
-    math::uint2 attachmentSize = {};
-    std::vector<wgpu::RenderPassColorAttachment> colorAttachments{};
-};
+    MRT mColorAttachments{};
+    Attachment mDepthAttachment{};
+    Attachment mStencilAttachment{};
 
+    // Cached descriptors for the render pass
+    std::vector<wgpu::RenderPassColorAttachment> mColorAttachmentDescriptors;
+    wgpu::RenderPassDepthStencilAttachment mDepthStencilAttachmentDescriptor{};
+    bool mHasDepthStencilAttachment = false;
+};
 }// namespace filament::backend
 #endif// TNT_FILAMENT_BACKEND_WEBGPUHANDLES_H

filament/backend/src/webgpu/WebGPUPipelineCreation.cpp

@@ -191,8 +191,8 @@ wgpu::RenderPipeline createWebGPURenderPipeline(wgpu::Device const& device,
             .entryPoint = "main",
             .constantCount = program.constants.size(),
             .constants = program.constants.data(),
-            .bufferCount = vertexBufferInfo.getVertexBufferLayoutSize(),
-            .buffers = vertexBufferInfo.getVertexBufferLayout()
+            .bufferCount = vertexBufferInfo.getWebGPULayoutCount(),
+            .buffers = vertexBufferInfo.getWebGPULayouts()
         },
         .primitive = {
             .topology = toWebGPU(primitiveType),

filament/backend/src/webgpu/WebGPUSwapChain.cpp

@@ -320,11 +320,14 @@ wgpu::TextureView WebGPUSwapChain::getCurrentSurfaceTextureView(
     if (surfaceTexture.status != wgpu::SurfaceGetCurrentTextureStatus::SuccessOptimal) {
         return nullptr;
     }
+
+    mCurrentSurfaceTexture = nullptr;
+    mCurrentSurfaceTexture = surfaceTexture.texture;
     // Create a view for this surface texture
     // TODO: review these initiliazations as webgpu pipeline gets mature
     wgpu::TextureViewDescriptor textureViewDescriptor = {
         .label = "surface_texture_view",
-        .format = surfaceTexture.texture.GetFormat(),
+        .format = mCurrentSurfaceTexture.GetFormat(),
         .dimension = wgpu::TextureViewDimension::e2D,
         .baseMipLevel = 0,
         .mipLevelCount = 1,
@@ -337,6 +340,7 @@ wgpu::TextureView WebGPUSwapChain::getCurrentSurfaceTextureView(
 void WebGPUSwapChain::present() {
     assert_invariant(mSurface);
     mSurface.Present();
+    mCurrentSurfaceTexture = nullptr;
 }
 
 }// namespace filament::backend

filament/backend/src/webgpu/WebGPUSwapChain.h

@@ -52,6 +52,8 @@ private:
     wgpu::TextureFormat mDepthFormat = wgpu::TextureFormat::Undefined;
     wgpu::Texture mDepthTexture = nullptr;
     wgpu::TextureView mDepthTextureView = nullptr;
+    wgpu::Texture mCurrentSurfaceTexture = nullptr; // To hold the texture from getCurrentTexture()
+
 };
 
 } // namespace filament::backend

libs/filamat/src/GLSLPostProcessor.cpp

@@ -48,7 +48,7 @@
 #include <unordered_map>
 #include <utility>
 #include <vector>
-
+#include "regex"
 #include <stddef.h>
 #include <stdint.h>
 
@@ -601,7 +601,6 @@ bool GLSLPostProcessor::spirvToWgsl(SpirvBlob *spirv, std::string *outWsl) {
         return false;
 #endif
     }
-
     tint::Result<tint::wgsl::writer::Output> wgslOut = tint::wgsl::writer::Generate(tintRead,writerOpts);
     /// An instance of SuccessType that can be used to check a tint Result.
     tint::SuccessType tintSuccess;
@@ -610,7 +609,9 @@ bool GLSLPostProcessor::spirvToWgsl(SpirvBlob *spirv, std::string *outWsl) {
         slog.e << "Tint writer error: " << wgslOut.Failure().reason << io::endl;
         return false;
     }
-    *outWsl = wgslOut->wgsl;
+    //Tint adds some annotations that Dawn complains about and needs removal
+    std::regex stride_regex(R"(@stride\([0-9]+\)\s*@internal\(disable_validation__ignore_stride\))");
+    *outWsl = std::regex_replace(wgslOut->wgsl, stride_regex, "");
     return true;
 #else
     slog.i << "Trying to emit WGSL without including WebGPU dependencies,"