Crafter.Graphics/implementations/Crafter.Graphics-UI-WebGPU.cpp

/*
Crafter®.Graphics
Copyright (C) 2026 Catcrafts®
catcrafts.net
*/

// WebGPU UIRenderer implementation — DOM mode parallel to
// Crafter.Graphics-UI.cpp. Compute pipelines and bind groups live JS-side
// in additional/dom-webgpu.js; this file just translates UIRenderer's
// public method calls into wgpu* import calls.

module Crafter.Graphics:UI_webgpu_impl;
import :UI;
import :Window;
import :Font;
import :FontAtlas;
import :WebGPU;
import :WebGPUBuffer;
import :DescriptorHeapWebGPU;
import :GraphicsTypes;
import std;

using namespace Crafter;

void UIRenderer::Initialize(Window& window, GraphicsDescriptorHeap& heap, GraphicsCommandBuffer initCmd,
                            std::filesystem::path /*quadsSpv*/,
                            std::filesystem::path /*circlesSpv*/,
                            std::filesystem::path /*imagesSpv*/,
                            std::filesystem::path /*textSpv*/) {
    (void)initCmd;
    window_ = &window;
    heap_   = &heap;

    // The JS bridge owns the compute pipelines (4 of them, precompiled at
    // page load). The C++ side has nothing to load. We do reserve one
    // image slot for the swapchain output (kept symmetrical with Vulkan)
    // and register the font atlas if one was set.
    auto outRange = heap_->AllocateImageSlots(1);
    outImageSlot_ = ImageSlot{heap_, outRange.firstElement};
    // No JS texture handle stored at this slot — the canvas's
    // getCurrentTexture() is per-frame and the JS bridge resolves it
    // internally. The slot value is only meaningful through
    // UIDispatchHeader.outImage, which the WGSL shaders ignore.

    if (fontAtlas != nullptr) {
        auto atlasImg = heap_->AllocateImageSlots(1);
        fontAtlasImageSlot_ = ImageSlot{heap_, atlasImg.firstElement};
        heap_->imageTable[atlasImg.firstElement] = fontAtlas->textureHandle;
        fontAtlasSamplerSlot_ = RegisterLinearClampSampler();
    }

    resizeSub_.SetEvent(&window.onResize, [this]() {
        // Storage textures + bind groups are recreated JS-side at next
        // wgpuFrameBegin (via the ensureSized path). Nothing to do here.
    });
}

void UIRenderer::Record(GraphicsCommandBuffer cmd, std::uint32_t frameIdx, Window& window) {
    if (fontAtlas != nullptr && fontAtlas->dirty) {
        fontAtlas->Update(cmd);
    }
    onBuild.Invoke({cmd, frameIdx});
    if (fontAtlas != nullptr && fontAtlas->dirty) {
        fontAtlas->Update(cmd);
    }
    (void)window;
}

namespace {
    inline std::uint32_t TilesFor(std::uint32_t dim) { return (dim + 7u) / 8u; }
}

void UIRenderer::DispatchQuads(GraphicsCommandBuffer /*cmd*/, std::uint32_t bufferSlot,
                               std::uint32_t itemCount,
                               std::array<float,4> clipRectPx) {
    if (itemCount == 0) return;
    UIDispatchHeader hdr = FillHeader(bufferSlot, itemCount, clipRectPx);
    auto handle = heap_->bufferTable[bufferSlot];
    WebGPU::wgpuDispatchQuads(handle, &hdr,
        static_cast<std::int32_t>(TilesFor(window_->width)),
        static_cast<std::int32_t>(TilesFor(window_->height)));
}

void UIRenderer::DispatchCircles(GraphicsCommandBuffer /*cmd*/, std::uint32_t bufferSlot,
                                 std::uint32_t itemCount,
                                 std::array<float,4> clipRectPx) {
    if (itemCount == 0) return;
    UIDispatchHeader hdr = FillHeader(bufferSlot, itemCount, clipRectPx);
    auto handle = heap_->bufferTable[bufferSlot];
    WebGPU::wgpuDispatchCircles(handle, &hdr,
        static_cast<std::int32_t>(TilesFor(window_->width)),
        static_cast<std::int32_t>(TilesFor(window_->height)));
}

void UIRenderer::DispatchImages(GraphicsCommandBuffer /*cmd*/, std::uint32_t bufferSlot,
                                std::uint32_t itemCount,
                                std::array<float,4> clipRectPx) {
    if (itemCount == 0) return;
    UIDispatchHeader hdr = FillHeader(bufferSlot, itemCount, clipRectPx);
    auto handle = heap_->bufferTable[bufferSlot];
    // For DispatchImages, the WGSL expects a texture + sampler in group 3.
    // The library v1 doesn't expose user-image registration on DOM (out of
    // scope per plan). If the user calls DispatchImages without a registered
    // image, fall back to using the font atlas binding — the user's items
    // should reference texSlot/sampSlot but on DOM those are ignored. For
    // now, route through the font atlas texture if available; otherwise
    // skip the dispatch.
    if (fontAtlasImageSlot_) {
        auto texHandle  = heap_->imageTable[fontAtlasImageSlot_];
        auto sampHandle = heap_->samplerTable[fontAtlasSamplerSlot_];
        WebGPU::wgpuDispatchImages(handle, &hdr,
            static_cast<std::int32_t>(TilesFor(window_->width)),
            static_cast<std::int32_t>(TilesFor(window_->height)),
            texHandle, sampHandle);
    }
}

void UIRenderer::DispatchText(GraphicsCommandBuffer /*cmd*/, std::uint32_t bufferSlot,
                              std::uint32_t itemCount,
                              std::array<float,4> clipRectPx) {
    if (itemCount == 0) return;
    if (!fontAtlasImageSlot_) {
        std::println("UIRenderer::DispatchText: no FontAtlas registered (set fontAtlas before Initialize)");
        std::abort();
    }
    UIDispatchHeader hdr = FillHeader(bufferSlot, itemCount, clipRectPx);
    auto bufHandle  = heap_->bufferTable[bufferSlot];
    auto texHandle  = heap_->imageTable[fontAtlasImageSlot_];
    auto sampHandle = heap_->samplerTable[fontAtlasSamplerSlot_];
    WebGPU::wgpuDispatchText(bufHandle, &hdr,
        static_cast<std::int32_t>(TilesFor(window_->width)),
        static_cast<std::int32_t>(TilesFor(window_->height)),
        texHandle, sampHandle);
}

SamplerSlot UIRenderer::RegisterLinearClampSampler() {
    auto range = heap_->AllocateSamplerSlots(1);
    heap_->samplerTable[range.firstElement] = WebGPU::wgpuCreateLinearClampSampler();
    return SamplerSlot{heap_, range.firstElement};
}