renderer/include/rive/renderer/rive_renderer.hpp

/*
 * Copyright 2022 Rive
 */

#pragma once

#include "rive/math/raw_path.hpp"
#include "rive/renderer.hpp"
#include "rive/renderer/gpu.hpp"
#include "rive/renderer/draw.hpp"
#include "rive/renderer/render_context.hpp"
#include <vector>

namespace rive::gpu
{
class RenderContext;
} // namespace rive::gpu

namespace rive
{
class GrInnerFanTriangulator;
class RiveRenderPath;
class RiveRenderPaint;

// Renderer implementation for Rive's pixel local storage renderer.
class RiveRenderer : public Renderer
{
public:
    RiveRenderer(gpu::RenderContext*);
    ~RiveRenderer() override;

    void save() override;
    void restore() override;
    void transform(const Mat2D& matrix) override;
    void drawPath(RenderPath*, RenderPaint*) override;
    void clipPath(RenderPath*) override;
    void drawImage(const RenderImage*,
                   ImageSampler,
                   BlendMode,
                   float opacity) override;
    void drawImageMesh(const RenderImage*,
                       ImageSampler,
                       rcp<RenderBuffer> vertices_f32,
                       rcp<RenderBuffer> uvCoords_f32,
                       rcp<RenderBuffer> indices_u16,
                       uint32_t vertexCount,
                       uint32_t indexCount,
                       BlendMode,
                       float opacity) override;

    // Determines if a path is an axis-aligned rectangle that can be represented
    // by rive::AABB.
    static bool IsAABB(const RawPath&, AABB* result);

#ifdef TESTING
    bool hasClipRect() const
    {
        return m_stack.back().clipRectInverseMatrix != nullptr;
    }
    const AABB& getClipRect() const { return m_stack.back().clipRect; }
    const Mat2D& getClipRectMatrix() const
    {
        return m_stack.back().clipRectMatrix;
    }
#endif

private:
    void clipRectImpl(AABB, const RiveRenderPath* originalPath);
    void clipPathImpl(const RiveRenderPath*);

    // Clips and pushes the given draw to m_context. If the clipped draw is too
    // complex to be supported by the GPU buffers, even after a logical flush,
    // then nothing is drawn.
    void clipAndPushDraw(gpu::DrawUniquePtr);

    // Pushes any necessary clip updates to m_internalDrawBatch and sets the
    // Draw's clipID and clipRectInverseMatrix, if any. Returns failure if the
    // operation failed, at which point the caller should issue a logical flush
    // and try again.
    enum class ApplyClipResult
    {
        success,
        failure,
        clipEmpty,
    };
    [[nodiscard]] ApplyClipResult applyClip(gpu::Draw*);

    struct RenderState
    {
        Mat2D matrix;
        size_t clipStackHeight = 0;
        AABB clipRect;
        Mat2D clipRectMatrix;
        const gpu::ClipRectInverseMatrix* clipRectInverseMatrix = nullptr;
        bool clipIsEmpty = false;
    };
    std::vector<RenderState> m_stack{1};

    struct ClipElement
    {
        ClipElement() = default;
        ClipElement(const Mat2D&, const RiveRenderPath*, FillRule);
        ~ClipElement();

        void reset(const Mat2D&, const RiveRenderPath*, FillRule);
        bool isEquivalent(const Mat2D&, const RiveRenderPath*) const;

        Mat2D matrix;
        uint64_t rawPathMutationID;
        AABB pathBounds;
        rcp<const RiveRenderPath> path;
        FillRule fillRule; // Bc RiveRenderPath fillRule can mutate during the
                           // artboard draw process.
        uint32_t clipID;
    };
    std::vector<ClipElement> m_clipStack;

    gpu::RenderContext* const m_context;

    std::vector<gpu::DrawUniquePtr> m_internalDrawBatch;

    // Path of the rectangle [0, 0, 1, 1]. Used to draw images.
    rcp<RiveRenderPath> m_unitRectPath;

    // Used to build coarse path interiors for the "interior triangulation"
    // algorithm.
    RawPath m_scratchPath;
};
} // namespace rive