MapLibreParticleLab/src/mbgl/renderer/render_layer.hpp

#pragma once
#include <list>
#include <mbgl/layout/layout.hpp>
#include <mbgl/renderer/render_pass.hpp>
#include <mbgl/renderer/render_source.hpp>
#include <mbgl/style/layer_properties.hpp>
#include <mbgl/tile/geometry_tile_data.hpp>
#include <mbgl/util/mat4.hpp>
#include <memory>
#include <string>

namespace mbgl {

class Bucket;
class TransitionParameters;
class PropertyEvaluationParameters;
class UploadParameters;
class PaintParameters;
class RenderTile;
class TransformState;
class PatternAtlas;
class LineAtlas;
class SymbolBucket;
class DynamicFeatureIndex;

class LayerRenderData {
public:
    std::shared_ptr<Bucket> bucket;
    Immutable<style::LayerProperties> layerProperties;
};

class SortKeyRange {
public:
    bool isFirstRange() const { return start == 0u; }
    float sortKey;
    size_t start;
    size_t end;
};

class BucketPlacementData {
public:
    std::reference_wrapper<Bucket> bucket;
    std::reference_wrapper<const RenderTile> tile;
    std::shared_ptr<FeatureIndex> featureIndex;
    std::string sourceId;
    optional<SortKeyRange> sortKeyRange;
};

using LayerPlacementData = std::list<BucketPlacementData>;

class LayerPrepareParameters {
public:
    RenderSource* source;
    ImageManager& imageManager;
    PatternAtlas& patternAtlas;
    LineAtlas& lineAtlas;
    const TransformState& state;
};

class RenderLayer {
protected:
    RenderLayer(Immutable<style::LayerProperties>);

public:
    virtual ~RenderLayer() = default;

    // Begin transitions for any properties that have changed since the last frame.
    virtual void transition(const TransitionParameters&) = 0;

    // Overloaded version for transitions to a new layer impl.
    void transition(const TransitionParameters&, Immutable<style::Layer::Impl> newImpl);

    // Fully evaluate possibly-transitioning paint properties based on a zoom level.
    // Updates the contained `evaluatedProperties` member.
    virtual void evaluate(const PropertyEvaluationParameters&) = 0;

    // Returns true if any paint properties have active transitions.
    virtual bool hasTransition() const = 0;

    // Returns true if the layer has a pattern property and is actively crossfading.
    virtual bool hasCrossfade() const = 0;

    // Returns true if layer writes to depth buffer by drawing using PaintParameters::depthModeFor3D().
    virtual bool is3D() const { return false; }

    // Returns true is the layer is subject to placement.
    bool needsPlacement() const;

    const std::string& getID() const;

    // Checks whether this layer needs to be rendered in the given render pass.
    bool hasRenderPass(RenderPass) const;

    // Checks whether this layer can be rendered.
    bool needsRendering() const;

    // Checks whether the given zoom is inside this layer zoom range.
    bool supportsZoom(float zoom) const;

    virtual void upload(gfx::UploadPass&) {}
    virtual void render(PaintParameters&) = 0;

    // Check wether the given geometry intersects
    // with the feature
    virtual bool queryIntersectsFeature(const GeometryCoordinates&, const GeometryTileFeature&, const float,
                                        const TransformState&, const float, const mat4&, const FeatureState&) const {
        return false;
    };

    virtual void populateDynamicRenderFeatureIndex(DynamicFeatureIndex&) const {}

    virtual void prepare(const LayerPrepareParameters&);

    const LayerPlacementData& getPlacementData() const { return placementData; }

    // Latest evaluated properties.
    Immutable<style::LayerProperties> evaluatedProperties;
    // Private implementation
    Immutable<style::Layer::Impl> baseImpl;

    virtual void markContextDestroyed();

    // TODO: Only for background layers.
    virtual optional<Color> getSolidBackground() const;

protected:
    // Checks whether the current hardware can render this layer. If it can't, we'll show a warning
    // in the console to inform the developer.
    void checkRenderability(const PaintParameters&, uint32_t activeBindingCount);

    void addRenderPassesFromTiles();

    const LayerRenderData* getRenderDataForPass(const RenderTile&, RenderPass) const;

protected:
    // Stores current set of tiles to be rendered for this layer.
    RenderTiles renderTiles;

    // Stores what render passes this layer is currently enabled for. This depends on the
    // evaluated StyleProperties object and is updated accordingly.
    RenderPass passes = RenderPass::None;

    LayerPlacementData placementData;

private:
    // Some layers may not render correctly on some hardware when the vertex attribute limit of
    // that GPU is exceeded. More attributes are used when adding many data driven paint properties
    // to a layer.
    bool hasRenderFailures = false;
};

using RenderLayerReferences = std::vector<std::reference_wrapper<RenderLayer>>;

} // namespace mbgl