include/rive/pls/pls_render_context.hpp

/*
 * Copyright 2022 Rive
 */

#pragma once

#include "rive/math/vec2d.hpp"
#include "rive/pls/pls.hpp"
#include "rive/pls/pls_factory.hpp"
#include "rive/pls/pls_render_target.hpp"
#include "rive/pls/trivial_block_allocator.hpp"
#include "rive/shapes/paint/color.hpp"
#include <array>
#include <unordered_map>

class PushRetrofittedTrianglesGMDraw;
class PLSRenderContextTest;

namespace rive
{
class RawPath;
} // namespace rive

namespace rive::pls
{
class GradientLibrary;
class IntersectionBoard;
class ImageMeshDraw;
class ImageRectDraw;
class InteriorTriangulationDraw;
class MidpointFanPathDraw;
class StencilClipReset;
class PLSDraw;
class PLSGradient;
class PLSPaint;
class PLSPath;
class PLSPathDraw;
class PLSRenderContextImpl;

// Used as a key for complex gradients.
class GradientContentKey
{
public:
    inline GradientContentKey(rcp<const PLSGradient> gradient);
    inline GradientContentKey(GradientContentKey&& other);
    bool operator==(const GradientContentKey&) const;
    const PLSGradient* gradient() const { return m_gradient.get(); }

private:
    rcp<const PLSGradient> m_gradient;
};

// Hashes all stops and all colors in a complex gradient.
class DeepHashGradient
{
public:
    size_t operator()(const GradientContentKey&) const;
};

// Even though PLSDraw is block-allocated, we still need to call releaseRefs() on each individual
// instance before releasing the block. This smart pointer guarantees we always call releaseRefs()
// (implementation in pls_draw.hpp).
struct PLSDrawReleaseRefs
{
    void operator()(PLSDraw* draw);
};
using PLSDrawUniquePtr = std::unique_ptr<PLSDraw, PLSDrawReleaseRefs>;

// Top-level, API agnostic rendering context for PLSRenderer. This class manages all the GPU
// buffers, context state, and other resources required for Rive's pixel local storage path
// rendering algorithm.
//
// Intended usage pattern of this class:
//
//   context->beginFrame(...);
//   for (path : paths)
//   {
//       context->pushPath(...);
//       for (contour : path.contours)
//       {
//           context->pushContour(...);
//           for (cubic : contour.cubics)
//           {
//               context->pushCubic(...);
//           }
//       }
//   }
//   context->flush();
class PLSRenderContext : public PLSFactory
{
public:
    PLSRenderContext(std::unique_ptr<PLSRenderContextImpl>);
    ~PLSRenderContext();

    PLSRenderContextImpl* impl() { return m_impl.get(); }
    template <typename T> T* static_impl_cast() { return static_cast<T*>(m_impl.get()); }

    const pls::PlatformFeatures& platformFeatures() const;

    // Options for controlling how and where a frame is rendered.
    struct FrameDescriptor
    {
        uint32_t renderTargetWidth = 0;
        uint32_t renderTargetHeight = 0;
        LoadAction loadAction = LoadAction::clear;
        ColorInt clearColor = 0;
        int msaaSampleCount = 0; // If nonzero, the number of MSAA samples to use.
                                 // Setting this to a nonzero value forces depthStencil mode.
        bool disableRasterOrdering = false; // Use atomic mode in place of rasterOrdering, even if
                                            // rasterOrdering is supported.

        // Testing flags.
        bool wireframe = false;
        bool fillsDisabled = false;
        bool strokesDisabled = false;
    };

    // Called at the beginning of a frame and establishes where and how it will be rendered.
    //
    // All rendering related calls must be made between beginFrame() and flush().
    void beginFrame(const FrameDescriptor&);

    const FrameDescriptor& frameDescriptor() const
    {
        assert(m_didBeginFrame);
        return m_frameDescriptor;
    }

    // True if bounds is empty or outside [0, 0, renderTargetWidth, renderTargetHeight].
    bool isOutsideCurrentFrame(const IAABB& pixelBounds);

    // True if the current frame supports draws with clipRects (clipRectInverseMatrix != null).
    // If false, all clipping must be done with clipPaths.
    bool frameSupportsClipRects() const;

    // If the frame doesn't support image paints, the client must draw images with pushImageRect().
    // If it DOES support image paints, the client CANNOT use pushImageRect(); it should draw images
    // as rectangular paths with an image paint.
    bool frameSupportsImagePaintForPaths() const;

    const pls::InterlockMode frameInterlockMode() const { return m_frameInterlockMode; }

    // Generates a unique clip ID that is guaranteed to not exist in the current clip buffer, and
    // assigns a contentBounds to it.
    //
    // Returns 0 if a unique ID could not be generated, at which point the caller must issue a
    // logical flush and try again.
    uint32_t generateClipID(const IAABB& contentBounds);

    // Screen-space bounding box of the region inside the given clip.
    const IAABB& getClipContentBounds(uint32_t clipID)
    {
        assert(m_didBeginFrame);
        assert(!m_logicalFlushes.empty());
        return m_logicalFlushes.back()->getClipInfo(clipID).contentBounds;
    }

    // Mark the given clip as being read from within a screen-space bounding box.
    void addClipReadBounds(uint32_t clipID, const IAABB& bounds)
    {
        assert(m_didBeginFrame);
        assert(!m_logicalFlushes.empty());
        return m_logicalFlushes.back()->addClipReadBounds(clipID, bounds);
    }

    // Union of screen-space bounding boxes from all draws that read the given clip element.
    const IAABB& getClipReadBounds(uint32_t clipID)
    {
        assert(m_didBeginFrame);
        assert(!m_logicalFlushes.empty());
        return m_logicalFlushes.back()->getClipInfo(clipID).readBounds;
    }

    // Get/set a "clip content ID" that uniquely identifies the current contents of the clip buffer.
    // This ID is reset to 0 on every logical flush.
    void setClipContentID(uint32_t clipID)
    {
        assert(m_didBeginFrame);
        m_clipContentID = clipID;
    }

    uint32_t getClipContentID()
    {
        assert(m_didBeginFrame);
        return m_clipContentID;
    }

    // Appends a list of high-level PLSDraws to the current frame.
    // Returns false if the draws don't fit within the current resource constraints, at which point
    // the caller must issue a logical flush and try again.
    [[nodiscard]] bool pushDrawBatch(PLSDrawUniquePtr draws[], size_t drawCount);

    // Records a "logical" flush, in that it builds up commands to break up the render pass and
    // re-render the resource textures, but it won't submit any command buffers or
    // rotate/synchronize the buffer rings.
    void logicalFlush();

    // GPU resources required to execute the GPU commands for a frame.
    struct FlushResources
    {
        PLSRenderTarget* renderTarget = nullptr;
        void* externalCommandBuffer = nullptr; // Required on Metal.
    };

    // Submits all GPU commands that have been built up since beginFrame().
    void flush(const FlushResources&);

    // Called when the client will stop rendering. Releases all CPU and GPU resources associated
    // with this render context.
    void releaseResources();

    // Returns the context's TrivialBlockAllocator, which is automatically reset at the end of every
    // frame. (Memory in this allocator is preserved between logical flushes.)
    TrivialBlockAllocator& perFrameAllocator()
    {
        assert(m_didBeginFrame);
        return m_perFrameAllocator;
    }

    // Allocators for intermediate path processing buffers.
    TrivialArrayAllocator<uint8_t>& numChopsAllocator() { return m_numChopsAllocator; }
    TrivialArrayAllocator<Vec2D>& chopVerticesAllocator() { return m_chopVerticesAllocator; }
    TrivialArrayAllocator<std::array<Vec2D, 2>>& tangentPairsAllocator()
    {
        return m_tangentPairsAllocator;
    }
    TrivialArrayAllocator<uint32_t, alignof(float4)>& polarSegmentCountsAllocator()
    {
        return m_polarSegmentCountsAllocator;
    }
    TrivialArrayAllocator<uint32_t, alignof(float4)>& parametricSegmentCountsAllocator()
    {
        return m_parametricSegmentCountsAllocator;
    }

    // Allocates a trivially destructible object that will be automatically dropped at the end of
    // the current frame.
    template <typename T, typename... Args> T* make(Args&&... args)
    {
        assert(m_didBeginFrame);
        return m_perFrameAllocator.make<T>(std::forward<Args>(args)...);
    }

    // Backend-specific PLSFactory implementation.
    rcp<RenderBuffer> makeRenderBuffer(RenderBufferType, RenderBufferFlags, size_t) override;
    rcp<RenderImage> decodeImage(Span<const uint8_t>) override;

private:
    friend class PLSDraw;
    friend class PLSPathDraw;
    friend class MidpointFanPathDraw;
    friend class InteriorTriangulationDraw;
    friend class ImageRectDraw;
    friend class ImageMeshDraw;
    friend class StencilClipReset;
    friend class ::PushRetrofittedTrianglesGMDraw; // For testing.
    friend class ::PLSRenderContextTest;           // For testing.

    // Resets the CPU-side STL containers so they don't have unbounded growth.
    void resetContainers();

    // Defines the exact size of each of our GPU resources. Computed during flush(), based on
    // LogicalFlush::ResourceCounters and LogicalFlush::LayoutCounters.
    struct ResourceAllocationCounts
    {
        using VecType = simd::gvec<size_t, 12>;

        RIVE_ALWAYS_INLINE VecType toVec() const
        {
            static_assert(sizeof(VecType) >= sizeof(*this));
            VecType vec;
            RIVE_INLINE_MEMCPY(&vec, this, sizeof(*this));
            return vec;
        }

        RIVE_ALWAYS_INLINE ResourceAllocationCounts(const VecType& vec)
        {
            static_assert(sizeof(VecType) >= sizeof(*this));
            RIVE_INLINE_MEMCPY(this, &vec, sizeof(*this));
        }

        ResourceAllocationCounts() = default;

        size_t flushUniformBufferCount = 0;
        size_t imageDrawUniformBufferCount = 0;
        size_t pathBufferCount = 0;
        size_t paintBufferCount = 0;
        size_t paintAuxBufferCount = 0;
        size_t contourBufferCount = 0;
        size_t simpleGradientBufferCount = 0;
        size_t complexGradSpanBufferCount = 0;
        size_t tessSpanBufferCount = 0;
        size_t triangleVertexBufferCount = 0;
        size_t gradTextureHeight = 0;
        size_t tessTextureHeight = 0;
    };

    // Reallocates GPU resources and updates m_currentResourceAllocations.
    // If forceRealloc is true, every GPU resource is allocated, even if the size would not change.
    void setResourceSizes(ResourceAllocationCounts, bool forceRealloc = false);

    void mapResourceBuffers(const ResourceAllocationCounts&);
    void unmapResourceBuffers();

    const std::unique_ptr<PLSRenderContextImpl> m_impl;
    const size_t m_maxPathID;

    ResourceAllocationCounts m_currentResourceAllocations;
    ResourceAllocationCounts m_maxRecentResourceRequirements;
    double m_lastResourceTrimTimeInSeconds;

    // Per-frame state.
    FrameDescriptor m_frameDescriptor;
    pls::InterlockMode m_frameInterlockMode;
    pls::ShaderFeatures m_frameShaderFeaturesMask;
    RIVE_DEBUG_CODE(bool m_didBeginFrame = false;)

    // Clipping state.
    uint32_t m_clipContentID = 0;

    // Used by LogicalFlushes for re-ordering high level draws.
    std::vector<int64_t> m_indirectDrawList;
    std::unique_ptr<IntersectionBoard> m_intersectionBoard;

    WriteOnlyMappedMemory<pls::FlushUniforms> m_flushUniformData;
    WriteOnlyMappedMemory<pls::PathData> m_pathData;
    WriteOnlyMappedMemory<pls::PaintData> m_paintData;
    WriteOnlyMappedMemory<pls::PaintAuxData> m_paintAuxData;
    WriteOnlyMappedMemory<pls::ContourData> m_contourData;
    // Simple gradients get written by the CPU.
    WriteOnlyMappedMemory<pls::TwoTexelRamp> m_simpleColorRampsData;
    // Complex gradients get rendered by the GPU.
    WriteOnlyMappedMemory<pls::GradientSpan> m_gradSpanData;
    WriteOnlyMappedMemory<pls::TessVertexSpan> m_tessSpanData;
    WriteOnlyMappedMemory<pls::TriangleVertex> m_triangleVertexData;
    WriteOnlyMappedMemory<pls::ImageDrawUniforms> m_imageDrawUniformData;

    // Simple allocator for trivially-destructible data that needs to persist until the current
    // frame has completed. All memory in this allocator is dropped at the end of the every frame.
    constexpr static size_t kPerFlushAllocatorInitialBlockSize = 1024 * 1024; // 1 MiB.
    TrivialBlockAllocator m_perFrameAllocator{kPerFlushAllocatorInitialBlockSize};

    // Allocators for intermediate path processing buffers.
    constexpr static size_t kIntermediateDataInitialStrokes = 8192;     // * 84 == 688 KiB.
    constexpr static size_t kIntermediateDataInitialFillCurves = 32768; // * 4 == 128 KiB.
    TrivialArrayAllocator<uint8_t> m_numChopsAllocator{kIntermediateDataInitialStrokes *
                                                       4}; // 4 byte per stroke curve.
    TrivialArrayAllocator<Vec2D> m_chopVerticesAllocator{kIntermediateDataInitialStrokes *
                                                         4}; // 32 bytes per stroke curve.
    TrivialArrayAllocator<std::array<Vec2D, 2>> m_tangentPairsAllocator{
        kIntermediateDataInitialStrokes * 2}; // 32 bytes per stroke curve.
    TrivialArrayAllocator<uint32_t, alignof(float4)> m_polarSegmentCountsAllocator{
        kIntermediateDataInitialStrokes * 4}; // 16 bytes per stroke curve.
    TrivialArrayAllocator<uint32_t, alignof(float4)> m_parametricSegmentCountsAllocator{
        kIntermediateDataInitialFillCurves}; // 4 bytes per fill curve.

    // Manages a list of high-level PLSDraws and their required resources.
    //
    // Since textures have hard size limits, we can't always fit an entire frame into one flush.
    // It's rare for us to require more than one flush in a single frame, but for the times that we
    // do, this flush logic is encapsulated in a nested class that can be built up into a list and
    // executed the end of a frame.
    class LogicalFlush
    {
    public:
        LogicalFlush(PLSRenderContext* parent);

        // Rewinds this flush object back to an empty state without shrinking any internal
        // allocations held by CPU-side STL containers.
        void rewind();

        // Resets the CPU-side STL containers so they don't have unbounded growth.
        void resetContainers();

        // Access this flush's pls::FlushDescriptor (which is not valid until layoutResources()).
        // NOTE: Some fields in the FlushDescriptor (tessVertexSpanCount, hasTriangleVertices,
        // drawList, and combinedShaderFeatures) do not become valid until after writeResources().
        const pls::FlushDescriptor& desc()
        {
            assert(m_hasDoneLayout);
            return m_flushDesc;
        }

        // Generates a unique clip ID that is guaranteed to not exist in the current clip buffer.
        //
        // Returns 0 if a unique ID could not be generated, at which point the caller must issue a
        // logical flush and try again.
        uint32_t generateClipID(const IAABB& contentBounds);

        struct ClipInfo
        {
            ClipInfo(const IAABB& contentBounds_) : contentBounds(contentBounds_) {}

            // Screen-space bounding box of the region inside the clip.
            const IAABB contentBounds;

            // Union of screen-space bounding boxes from all draws that read the clip.
            //
            // (Initialized with a maximally negative rectangle whose union with any other rectangle
            // will be equal to that same rectangle.)
            IAABB readBounds = {std::numeric_limits<int32_t>::max(),
                                std::numeric_limits<int32_t>::max(),
                                std::numeric_limits<int32_t>::min(),
                                std::numeric_limits<int32_t>::min()};
        };

        const ClipInfo& getClipInfo(uint32_t clipID) { return getWritableClipInfo(clipID); }

        // Mark the given clip as being read from within a screen-space bounding box.
        void addClipReadBounds(uint32_t clipID, const IAABB& bounds);

        // Appends a list of high-level PLSDraws to the flush.
        // Returns false if the draws don't fit within the current resource constraints, at which
        // point the context must append a new logical flush and try again.
        [[nodiscard]] bool pushDrawBatch(PLSDrawUniquePtr draws[], size_t drawCount);

        // Running counts of data records required by PLSDraws that need to be allocated in the
        // render context's various GPU buffers.
        struct ResourceCounters
        {
            using VecType = simd::gvec<size_t, 8>;

            VecType toVec() const
            {
                static_assert(sizeof(VecType) == sizeof(*this));
                VecType vec;
                RIVE_INLINE_MEMCPY(&vec, this, sizeof(VecType));
                return vec;
            }

            ResourceCounters(const VecType& vec)
            {
                static_assert(sizeof(*this) == sizeof(VecType));
                RIVE_INLINE_MEMCPY(this, &vec, sizeof(*this));
            }

            ResourceCounters() = default;

            size_t midpointFanTessVertexCount = 0;
            size_t outerCubicTessVertexCount = 0;
            size_t pathCount = 0;
            size_t contourCount = 0;
            size_t maxTessellatedSegmentCount = 0; // lines, curves, lone joins, emulated caps, etc.
            size_t maxTriangleVertexCount = 0;
            size_t imageDrawCount = 0; // imageRect or imageMesh.
            size_t complexGradientSpanCount = 0;
        };

        // Additional counters for layout state that don't need to be tracked by individual draws.
        struct LayoutCounters
        {
            uint32_t pathPaddingCount = 0;
            uint32_t paintPaddingCount = 0;
            uint32_t paintAuxPaddingCount = 0;
            uint32_t contourPaddingCount = 0;
            uint32_t simpleGradCount = 0;
            uint32_t maxGradTextureHeight = 0;
            uint32_t maxTessTextureHeight = 0;
        };

        // Allocates a horizontal span of texels in the gradient texture and schedules either a
        // texture upload or a draw that fills it with the given gradient's color ramp.
        //
        // Fills out a ColorRampLocation record that tells the shader how to access the gradient.
        //
        // Returns false if the gradient texture is out of space, at which point the caller must
        // issue a logical flush and try again.
        [[nodiscard]] bool allocateGradient(const PLSGradient*,
                                            ResourceCounters*,
                                            pls::ColorRampLocation*);

        // Carves out space for this specific flush within the total frame's resource buffers and
        // lays out the flush-specific resource textures. Updates the total frame running conters
        // based on layout.
        void layoutResources(const FlushResources&,
                             size_t logicalFlushIdx,
                             bool isFinalFlushOfFrame,
                             ResourceCounters* runningFrameResourceCounts,
                             LayoutCounters* runningFrameLayoutCounts);

        // Called after all flushes in a frame have done their layout and the render context has
        // allocated and mapped its resource buffers. Writes the GPU data for this flush to the
        // context's actively mapped resource buffers.
        void writeResources();

        // Pushes a record to the GPU for the given path, which will be referenced by future calls
        // to pushContour() and pushCubic().
        void pushPath(PLSPathDraw*, pls::PatchType, uint32_t tessVertexCount);

        // Pushes a contour record to the GPU for the given contour, which references the
        // most-recently pushed path and will be referenced by future calls to pushCubic().
        //
        // The first curve of the contour will be pre-padded with 'paddingVertexCount' tessellation
        // vertices, colocated at T=0. The caller must use this argument to align the end of the
        // contour on a boundary of the patch size. (See pls::PaddingToAlignUp().)
        void pushContour(Vec2D midpoint, bool closed, uint32_t paddingVertexCount);

        // Appends a cubic curve and join to the most-recently pushed contour, and reserves the
        // appropriate number of tessellated vertices in the tessellation texture.
        //
        // An instance consists of a cubic curve with "parametricSegmentCount + polarSegmentCount"
        // segments, followed by a join with "joinSegmentCount" segments, for a grand total of
        // "parametricSegmentCount + polarSegmentCount + joinSegmentCount - 1" vertices.
        //
        // If a cubic has already been pushed to the current contour, pts[0] must be equal to the
        // former cubic's pts[3].
        //
        // "joinTangent" is the ending tangent of the join that follows the cubic.
        void pushCubic(const Vec2D pts[4],
                       Vec2D joinTangent,
                       uint32_t additionalContourFlags,
                       uint32_t parametricSegmentCount,
                       uint32_t polarSegmentCount,
                       uint32_t joinSegmentCount);

        // Pushes triangles to be drawn using the data records from the most recent calls to
        // pushPath() and pushPaint().
        void pushInteriorTriangulation(InteriorTriangulationDraw*);

        // Pushes an imageRect to the draw list.
        // This should only be used when we don't have bindless textures in atomic mode. Otherwise,
        // images should be drawn as rectangular paths with an image paint.
        void pushImageRect(ImageRectDraw*);

        void pushImageMesh(ImageMeshDraw*);

        void pushStencilClipReset(StencilClipReset*);

        // Adds a barrier to the end of the draw list that prevents further combining/batching and
        // instructs the backend to issue a graphics barrier, if necessary.
        void pushBarrier();

    private:
        ClipInfo& getWritableClipInfo(uint32_t clipID);

        // Writes padding vertices to the tessellation texture, with an invalid contour ID that is
        // guaranteed to not be the same ID as any neighbors.
        void pushPaddingVertices(uint32_t tessLocation, uint32_t count);

        // Allocates a (potentially wrapped) span in the tessellation texture and pushes an instance
        // to render it. If the span does wraps, pushes multiple instances to render each horizontal
        // segment.
        RIVE_ALWAYS_INLINE void pushTessellationSpans(const Vec2D pts[4],
                                                      Vec2D joinTangent,
                                                      uint32_t totalVertexCount,
                                                      uint32_t parametricSegmentCount,
                                                      uint32_t polarSegmentCount,
                                                      uint32_t joinSegmentCount,
                                                      uint32_t contourIDWithFlags);

        // Same as pushTessellationSpans(), but pushes a reflection of the span, rendered right to
        // left, whose triangles have reverse winding directions and negated coverage.
        RIVE_ALWAYS_INLINE void pushMirroredTessellationSpans(const Vec2D pts[4],
                                                              Vec2D joinTangent,
                                                              uint32_t totalVertexCount,
                                                              uint32_t parametricSegmentCount,
                                                              uint32_t polarSegmentCount,
                                                              uint32_t joinSegmentCount,
                                                              uint32_t contourIDWithFlags);

        // Functionally equivalent to "pushMirroredTessellationSpans(); pushTessellationSpans();",
        // but packs each forward and mirrored pair into a single pls::TessVertexSpan.
        RIVE_ALWAYS_INLINE void pushMirroredAndForwardTessellationSpans(
            const Vec2D pts[4],
            Vec2D joinTangent,
            uint32_t totalVertexCount,
            uint32_t parametricSegmentCount,
            uint32_t polarSegmentCount,
            uint32_t joinSegmentCount,
            uint32_t contourIDWithFlags);

        // Either appends a new drawBatch to m_drawList or merges into m_drawList.tail().
        // Updates the batch's ShaderFeatures according to the passed parameters.
        DrawBatch& pushPathDraw(PLSPathDraw*, DrawType, uint32_t vertexCount, uint32_t baseVertex);
        DrawBatch& pushDraw(PLSDraw*,
                            DrawType,
                            pls::PaintType,
                            uint32_t elementCount,
                            uint32_t baseElement);

        // Instance pointer to the outer parent class.
        PLSRenderContext* const m_ctx;

        // Running counts of GPU data records that need to be allocated for draws.
        ResourceCounters m_resourceCounts;

        // Simple gradients have one stop at t=0 and one stop at t=1. They're implemented with 2
        // texels.
        std::unordered_map<uint64_t, uint32_t> m_simpleGradients; // [color0, color1] -> texelsIdx.
        std::vector<pls::TwoTexelRamp> m_pendingSimpleGradientWrites;

        // Complex gradients have stop(s) between t=0 and t=1. In theory they should be scaled to a
        // ramp where every stop lands exactly on a pixel center, but for now we just always scale
        // them to the entire gradient texture width.
        std::unordered_map<GradientContentKey, uint16_t, DeepHashGradient>
            m_complexGradients; // [colors[0..n], stops[0..n]] -> rowIdx
        std::vector<const PLSGradient*> m_pendingComplexColorRampDraws;

        std::vector<ClipInfo> m_clips;

        // High-level draw list. These get built into a low-level list of pls::DrawBatch objects
        // during writeResources().
        std::vector<PLSDrawUniquePtr> m_plsDraws;
        IAABB m_combinedDrawBounds;

        // Layout state.
        uint32_t m_pathPaddingCount;
        uint32_t m_paintPaddingCount;
        uint32_t m_paintAuxPaddingCount;
        uint32_t m_contourPaddingCount;
        uint32_t m_midpointFanTessEndLocation;
        uint32_t m_outerCubicTessEndLocation;
        uint32_t m_outerCubicTessVertexIdx;
        uint32_t m_midpointFanTessVertexIdx;

        pls::FlushDescriptor m_flushDesc;
        pls::GradTextureLayout m_gradTextureLayout; // Not determined until writeResources().

        BlockAllocatedLinkedList<DrawBatch> m_drawList;
        pls::ShaderFeatures m_combinedShaderFeatures;

        // Most recent path and contour state.
        bool m_currentPathIsStroked;
        pls::ContourDirections m_currentPathContourDirections;
        uint32_t m_currentPathID;
        uint32_t m_currentContourID;
        uint32_t m_currentContourPaddingVertexCount; // Padding to add to the first curve.
        uint32_t m_pathTessLocation;
        uint32_t m_pathMirroredTessLocation; // Used for back-face culling and mirrored patches.
        RIVE_DEBUG_CODE(uint32_t m_expectedPathTessLocationAtEndOfPath;)
        RIVE_DEBUG_CODE(uint32_t m_expectedPathMirroredTessLocationAtEndOfPath;)
        RIVE_DEBUG_CODE(uint32_t m_pathCurveCount;)

        // Stateful Z index of the current draw being pushed. Used by depthStencil mode to avoid
        // double hits and to reverse-sort opaque paths front to back.
        uint32_t m_currentZIndex;

        RIVE_DEBUG_CODE(bool m_hasDoneLayout = false;)
    };

    std::vector<std::unique_ptr<LogicalFlush>> m_logicalFlushes;
};
} // namespace rive::pls