Gemini tinkering 3

filament/backend/include/backend/PixelBufferDescriptor.h

@@ -204,23 +204,15 @@ public:
                 }, new T(std::forward<T>(functor))
         };
     }
-
-    // --------------------------------------------------------------------------------------------
-
     /**
-     * Computes the size in bytes needed to fit an image of given dimensions and format
+     * Computes the size in bytes for a pixel of given dimensions and format
      *
      * @param format    Format of the image pixels
      * @param type      Type of the image pixels
-     * @param stride    Stride of a row in pixels
-     * @param height    Height of the image in rows
-     * @param alignment Alignment in bytes of pixel rows
-     * @return The buffer size needed to fit this image in bytes
+     * @return The size of the specified pixel in bytes
      */
-    static constexpr size_t computeDataSize(PixelDataFormat format, PixelDataType type,
-            size_t stride, size_t height, size_t alignment) noexcept {
-        assert_invariant(alignment);
 
+    static constexpr size_t computePixelSize(PixelDataFormat format, PixelDataType type) noexcept {
         if (type == PixelDataType::COMPRESSED) {
             return 0;
         }
@@ -242,7 +234,7 @@ public:
             case PixelDataFormat::RGB_INTEGER:
                 n = 3;
                 break;
-            case PixelDataFormat::UNUSED: // shouldn't happen (used to be rgbm)
+            case PixelDataFormat::UNUSED:// shouldn't happen (used to be rgbm)
             case PixelDataFormat::RGBA:
             case PixelDataFormat::RGBA_INTEGER:
                 n = 4;
@@ -251,7 +243,7 @@ public:
 
         size_t bpp = n;
         switch (type) {
-            case PixelDataType::COMPRESSED: // Impossible -- to squash the IDE warnings
+            case PixelDataType::COMPRESSED:// Impossible -- to squash the IDE warnings
             case PixelDataType::UBYTE:
             case PixelDataType::BYTE:
                 // nothing to do
@@ -282,16 +274,35 @@ public:
                 bpp = 2;
                 break;
         }
+        return bpp;
+    }
 
+    // --------------------------------------------------------------------------------------------
+
+    /**
+     * Computes the size in bytes needed to fit an image of given dimensions and format
+     *
+     * @param format    Format of the image pixels
+     * @param type      Type of the image pixels
+     * @param stride    Stride of a row in pixels
+     * @param height    Height of the image in rows
+     * @param alignment Alignment in bytes of pixel rows
+     * @return The buffer size needed to fit this image in bytes
+     */
+    static constexpr size_t computeDataSize(PixelDataFormat format, PixelDataType type,
+            size_t stride, size_t height, size_t alignment) noexcept {
+        assert_invariant(alignment);
+
+        size_t bpp = computePixelSize(format, type);
         size_t const bpr = bpp * stride;
         size_t const bprAligned = (bpr + (alignment - 1)) & (~alignment + 1);
         return bprAligned * height;
     }
 
     //! left coordinate in pixels
-    uint32_t left   = 0;
+    uint32_t left = 0;
     //! top coordinate in pixels
-    uint32_t top    = 0;
+    uint32_t top = 0;
     union {
         struct {
             //! stride in pixels

filament/backend/src/webgpu/WebGPUDriver.cpp

@@ -26,7 +26,7 @@
 #include <backend/DriverEnums.h>
 #include <backend/Handle.h>
 #include <backend/TargetBufferInfo.h>
-
+#include <private/backend/BackendUtils.h>
 #include <math/mat3.h>
 #include <utils/CString.h>
 #include <utils/Panic.h>
@@ -39,6 +39,7 @@
 #include <array>
 #include <cstddef>
 #include <cstdint>
+#include <memory>
 #include <sstream>
 #include <string_view>
 #include <utility>
@@ -353,6 +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) {
@@ -579,7 +591,21 @@ 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) {}
 
@@ -752,11 +778,72 @@ void WebGPUDriver::setVertexBufferObject(Handle<HwVertexBuffer> vbh, uint32_t in
     vertexBuffer->buffers[index] = bufferObject->getBuffer();
 }
 
-void WebGPUDriver::update3DImage(Handle<HwTexture> th,
-        uint32_t level, uint32_t xoffset, uint32_t yoffset, uint32_t zoffset,
-        uint32_t width, uint32_t height, uint32_t depth,
-        PixelBufferDescriptor&& data) {
-    scheduleDestroy(std::move(data));
+void WebGPUDriver::update3DImage(Handle<HwTexture> th, uint32_t level, uint32_t xoffset,
+        uint32_t yoffset, uint32_t zoffset, uint32_t width, uint32_t height, uint32_t depth,
+        PixelBufferDescriptor&& p) {
+    PixelBufferDescriptor* data = &p;
+    PixelBufferDescriptor reshapedData;
+    if (reshape(p, reshapedData)) {
+        data = &reshapedData;
+    }
+    auto texture = handleCast<WGPUTexture>(th);
+
+    // TODO: Writing to a depth texture is illegal and errors. I'm not sure why Filament is trying
+    // to do so, but early returning is working?
+    if(texture->getAspect() == wgpu::TextureAspect::DepthOnly){
+        scheduleDestroy(std::move(p));
+        return;
+    }
+    size_t blockWidth = texture->getBlockWidth();
+    size_t blockHeight = texture->getBlockHeight();
+    // WebGPU specification requires that for compressed textures, the x and y offsets
+    // must be a multiple of the compressed texture format's block width and height.
+    // See: https://www.w3.org/TR/webgpu/#abstract-opdef-validating-gputexelcopytextureinfo
+    if (blockWidth > 1 || blockHeight > 1) {
+        FILAMENT_CHECK_PRECONDITION(xoffset % blockWidth == 0)
+                << "xoffset must be aligned to blockwidth, but offset is " << blockWidth
+                << "and offset is " << xoffset;
+        FILAMENT_CHECK_PRECONDITION(yoffset % blockHeight == 0)
+                << "yoffset must be aligned to blockHeight, but offset is " << blockHeight
+                << "and offset is " << yoffset;
+    }
+
+    auto copyInfo = wgpu::TexelCopyTextureInfo{ .texture = texture->getTexture(),
+        .mipLevel = level,
+        .origin = { .x = xoffset, .y = yoffset, .z = zoffset },
+        .aspect = texture->getAspect() };
+    uint32_t bytesPerRow = static_cast<uint32_t>(
+            PixelBufferDescriptor::computePixelSize(data->format, data->type) * width);
+    auto extent = wgpu::Extent3D{ .width = width, .height = height, .depthOrArrayLayers = depth };
+
+    const uint8_t* dataBuff = static_cast<const uint8_t*>(data->buffer);
+    size_t dataSize = data->size;
+    std::unique_ptr<uint8_t[]> paddedBuffer;
+
+    if (bytesPerRow % 256 != 0) {
+        uint32_t padding = 256 - (bytesPerRow % 256);
+        uint32_t paddedBytesPerRow = bytesPerRow + padding;
+
+        size_t paddedBufferSize = static_cast<size_t>(paddedBytesPerRow) * height * depth;
+        paddedBuffer = std::make_unique<uint8_t[]>(paddedBufferSize);
+        uint8_t* dest = paddedBuffer.get();
+
+        for (uint32_t z = 0; z < depth; ++z) {
+            for (uint32_t y = 0; y < height; ++y) {
+                std::memcpy(dest, dataBuff, bytesPerRow);
+                dest += paddedBytesPerRow;
+                dataBuff += bytesPerRow;
+            }
+        }
+        dataBuff = paddedBuffer.get();
+        dataSize = paddedBufferSize;
+        bytesPerRow = paddedBytesPerRow;
+    }
+
+    auto layout = wgpu::TexelCopyBufferLayout{ .bytesPerRow = bytesPerRow, .rowsPerImage = height };
+
+    mQueue.WriteTexture(&copyInfo, dataBuff, dataSize, &layout, &extent);
+    scheduleDestroy(std::move(p));
 }
 
 void WebGPUDriver::setupExternalImage(void* image) {
@@ -783,35 +870,74 @@ 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 */) {

filament/backend/src/webgpu/WebGPUHandles.cpp

@@ -20,7 +20,7 @@
 
 #include <utils/BitmaskEnum.h>
 #include <utils/Panic.h>
-
+#include <private/backend/BackendUtils.h>
 #include <webgpu/webgpu_cpp.h>
 
 #include <algorithm>
@@ -68,7 +68,7 @@ wgpu::VertexFormat getVertexFormat(filament::backend::ElementType type, bool nor
             case ElementType::BYTE4: return VertexFormat::Snorm8x4;
             case ElementType::UBYTE4: return VertexFormat::Unorm8x4;
             case ElementType::SHORT4: return VertexFormat::Snorm16x4;
-            case ElementType::USHORT4: return VertexFormat::Unorm8x4;
+            case ElementType::USHORT4: return VertexFormat::Unorm16x4;
             default:
                 FILAMENT_CHECK_POSTCONDITION(false) << "Normalized format does not exist.";
                 return VertexFormat::Float32x3;
@@ -502,6 +502,8 @@ WGPUTexture::WGPUTexture(SamplerType target, uint8_t levels, TextureFormat forma
     mUsage = fToWGPUTextureUsage(usage);
     mFormat = fToWGPUTextureFormat(format);
     mAspect = fToWGPUTextureViewAspect(usage, format);
+    mBlockWidth = filament::backend::getBlockWidth(format);
+    mBlockHeight = filament::backend::getBlockHeight(format);
     wgpu::TextureDescriptor textureDescriptor{
         .label = getUserTextureLabel(target),
         .usage = mUsage,
@@ -548,6 +550,10 @@ WGPUTexture::WGPUTexture(SamplerType target, uint8_t levels, TextureFormat forma
 
 WGPUTexture::WGPUTexture(WGPUTexture* src, uint8_t baseLevel, uint8_t levelCount) noexcept {
     mTexture = src->mTexture;
+    mAspect = src->mAspect;
+    mBlockWidth = src->mBlockWidth;
+    mBlockHeight = src->mBlockHeight;
+
     mTexView = makeTextureView(baseLevel, levelCount, target);
 }
 
@@ -917,58 +923,147 @@ 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

@@ -161,6 +161,9 @@ public:
             wgpu::Device const& device) noexcept;
 
     WGPUTexture(WGPUTexture* src, uint8_t baseLevel, uint8_t levelCount) noexcept;
+    wgpu::TextureAspect getAspect() const { return mAspect; }
+    size_t getBlockWidth() const { return mBlockWidth; }
+    size_t getBlockHeight() const { return mBlockHeight; }
 
     [[nodiscard]] const wgpu::Texture& getTexture() const { return mTexture; }
     [[nodiscard]] const wgpu::TextureView& getTexView() const { return mTexView; }
@@ -184,6 +187,8 @@ private:
     uint32_t mArrayLayerCount = 1;
     wgpu::TextureView mTexView = nullptr;
     wgpu::TextureUsage fToWGPUTextureUsage(filament::backend::TextureUsage const& fUsage);
+    size_t mBlockWidth;
+    size_t mBlockHeight;
 };
 
 struct WGPURenderPrimitive : public HwRenderPrimitive {
@@ -192,57 +197,66 @@ 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