src/gpu/GrPipelineBuilder.h

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrPipelineBuilder_DEFINED
#define GrPipelineBuilder_DEFINED

#include "GrBlend.h"
#include "GrCaps.h"
#include "GrGpuResourceRef.h"
#include "GrProcOptInfo.h"
#include "GrRenderTarget.h"
#include "GrUserStencilSettings.h"
#include "GrXferProcessor.h"
#include "SkMatrix.h"
#include "effects/GrCoverageSetOpXP.h"
#include "effects/GrDisableColorXP.h"
#include "effects/GrPorterDuffXferProcessor.h"
#include "effects/GrSimpleTextureEffect.h"

class GrDrawBatch;
class GrCaps;
class GrPaint;
class GrTexture;

class GrPipelineBuilder : public SkNoncopyable {
public:
    GrPipelineBuilder();

    /**
     * Initializes the GrPipelineBuilder based on a GrPaint and MSAA availability. Note
     * that GrPipelineBuilder encompasses more than GrPaint. Aspects of GrPipelineBuilder that have
     * no GrPaint equivalents are set to default values with the exception of vertex attribute state
     * which is unmodified by this function and clipping which will be enabled.
     */
    GrPipelineBuilder(const GrPaint&, bool targetHasUnifiedMultisampling);

    virtual ~GrPipelineBuilder();

    ///////////////////////////////////////////////////////////////////////////
    /// @name Fragment Processors
    ///
    /// GrFragmentProcessors are used to compute per-pixel color and per-pixel fractional coverage.
    /// There are two chains of FPs, one for color and one for coverage. The first FP in each
    /// chain gets the initial color/coverage from the GrPrimitiveProcessor. It computes an output
    /// color/coverage which is fed to the next FP in the chain. The last color and coverage FPs
    /// feed their output to the GrXferProcessor which controls blending.
    ////

    int numColorFragmentProcessors() const { return fColorFragmentProcessors.count(); }
    int numCoverageFragmentProcessors() const { return fCoverageFragmentProcessors.count(); }
    int numFragmentProcessors() const { return this->numColorFragmentProcessors() +
                                               this->numCoverageFragmentProcessors(); }

    const GrFragmentProcessor* getColorFragmentProcessor(int idx) const {
        return fColorFragmentProcessors[idx];
    }
    const GrFragmentProcessor* getCoverageFragmentProcessor(int idx) const {
        return fCoverageFragmentProcessors[idx];
    }

    const GrFragmentProcessor* addColorFragmentProcessor(const GrFragmentProcessor* processor) {
        SkASSERT(processor);
        fColorFragmentProcessors.push_back(SkRef(processor));
        return processor;
    }

    const GrFragmentProcessor* addCoverageFragmentProcessor(const GrFragmentProcessor* processor) {
        SkASSERT(processor);
        fCoverageFragmentProcessors.push_back(SkRef(processor));
        return processor;
    }

    /**
     * Creates a GrSimpleTextureEffect that uses local coords as texture coordinates.
     */
    void addColorTextureProcessor(GrTexture* texture, const SkMatrix& matrix) {
        this->addColorFragmentProcessor(GrSimpleTextureEffect::Create(texture, matrix))->unref();
    }

    void addCoverageTextureProcessor(GrTexture* texture, const SkMatrix& matrix) {
        this->addCoverageFragmentProcessor(GrSimpleTextureEffect::Create(texture, matrix))->unref();
    }

    void addColorTextureProcessor(GrTexture* texture,
                                  const SkMatrix& matrix,
                                  const GrTextureParams& params) {
        this->addColorFragmentProcessor(GrSimpleTextureEffect::Create(texture, matrix,
                                                                      params))->unref();
    }

    void addCoverageTextureProcessor(GrTexture* texture,
                                     const SkMatrix& matrix,
                                     const GrTextureParams& params) {
        this->addCoverageFragmentProcessor(GrSimpleTextureEffect::Create(texture, matrix,
                                                                         params))->unref();
    }

    /**
     * When this object is destroyed it will remove any color/coverage FPs from the pipeline builder
     * that were added after its constructor.
     * This class can transiently modify its "const" GrPipelineBuilder object but will restore it
     * when done - so it is notionally "const" correct.
     */
    class AutoRestoreFragmentProcessorState : public ::SkNoncopyable {
    public:
        AutoRestoreFragmentProcessorState()
            : fPipelineBuilder(nullptr)
            , fColorEffectCnt(0)
            , fCoverageEffectCnt(0) {}

        AutoRestoreFragmentProcessorState(const GrPipelineBuilder& ds)
            : fPipelineBuilder(nullptr)
            , fColorEffectCnt(0)
            , fCoverageEffectCnt(0) {
            this->set(&ds);
        }

        ~AutoRestoreFragmentProcessorState() { this->set(nullptr); }

        void set(const GrPipelineBuilder* ds);

        bool isSet() const { return SkToBool(fPipelineBuilder); }

        const GrFragmentProcessor* addCoverageFragmentProcessor(
            const GrFragmentProcessor* processor) {
            SkASSERT(this->isSet());
            return fPipelineBuilder->addCoverageFragmentProcessor(processor);
        }

    private:
        // notionally const (as marginalia)
        GrPipelineBuilder*    fPipelineBuilder;
        int                   fColorEffectCnt;
        int                   fCoverageEffectCnt;
    };

    /// @}

    ///////////////////////////////////////////////////////////////////////////
    /// @name Blending
    ////

    /**
     * Installs a GrXPFactory. This object controls how src color, fractional pixel coverage,
     * and the dst color are blended.
     */
    const GrXPFactory* setXPFactory(const GrXPFactory* xpFactory) {
        fXPFactory.reset(SkSafeRef(xpFactory));
        return xpFactory;
    }

    /**
     * Sets a GrXPFactory that disables color writes to the destination. This is useful when
     * rendering to the stencil buffer.
     */
    void setDisableColorXPFactory() {
        fXPFactory.reset(GrDisableColorXPFactory::Create());
    }

    const GrXPFactory* getXPFactory() const {
        return fXPFactory;
    }

    /**
     * Checks whether the xp will need destination in a texture to correctly blend.
     */
    bool willXPNeedDstTexture(const GrCaps& caps,
                              const GrPipelineOptimizations& optimizations) const;

    /// @}


    ///////////////////////////////////////////////////////////////////////////
    /// @name Stencil
    ////

    bool hasUserStencilSettings() const { return !fUserStencilSettings->isUnused(); }
    const GrUserStencilSettings* getUserStencil() const { return fUserStencilSettings; }

    /**
     * Sets the user stencil settings for the next draw.
     * This class only stores pointers to stencil settings objects.
     * The caller guarantees the pointer will remain valid until it
     * changes or goes out of scope.
     * @param settings  the stencil settings to use.
     */
    void setUserStencil(const GrUserStencilSettings* settings) { fUserStencilSettings = settings; }
    void disableUserStencil() { fUserStencilSettings = &GrUserStencilSettings::kUnused; }

    /// @}

    ///////////////////////////////////////////////////////////////////////////
    /// @name State Flags
    ////

    /**
     *  Flags that affect rendering. Controlled using enable/disableState(). All
     *  default to disabled.
     */
    enum Flags {
        /**
         * Perform HW anti-aliasing. This means either HW FSAA, if supported by the render target,
         * or smooth-line rendering if a line primitive is drawn and line smoothing is supported by
         * the 3D API.
         */
        kHWAntialias_Flag   = 0x01,

        /**
         * Modifies the vertex shader so that vertices will be positioned at pixel centers.
         */
        kSnapVerticesToPixelCenters_Flag = 0x02,

        /**
         * Suppress linear -> sRGB conversion when rendering to sRGB render targets.
         */
        kDisableOutputConversionToSRGB_Flag = 0x04,

        /**
         * Allow sRGB -> linear conversion when reading from sRGB inputs.
         */
        kAllowSRGBInputs_Flag = 0x08,

        kLast_Flag = kAllowSRGBInputs_Flag,
    };

    bool isHWAntialias() const { return SkToBool(fFlags & kHWAntialias_Flag); }
    bool snapVerticesToPixelCenters() const {
        return SkToBool(fFlags & kSnapVerticesToPixelCenters_Flag); }
    bool getDisableOutputConversionToSRGB() const {
        return SkToBool(fFlags & kDisableOutputConversionToSRGB_Flag); }
    bool getAllowSRGBInputs() const {
        return SkToBool(fFlags & kAllowSRGBInputs_Flag); }

    /**
     * Enable render state settings.
     *
     * @param flags bitfield of Flags specifying the states to enable
     */
    void enableState(uint32_t flags) { fFlags |= flags; }

    /**
     * Disable render state settings.
     *
     * @param flags bitfield of Flags specifying the states to disable
     */
    void disableState(uint32_t flags) { fFlags &= ~(flags); }

    /**
     * Enable or disable flags based on a boolean.
     *
     * @param flags bitfield of Flags to enable or disable
     * @param enable    if true enable stateBits, otherwise disable
     */
    void setState(uint32_t flags, bool enable) {
        if (enable) {
            this->enableState(flags);
        } else {
            this->disableState(flags);
        }
    }

    /// @}

    ///////////////////////////////////////////////////////////////////////////
    /// @name Face Culling
    ////

    enum DrawFace {
        kInvalid_DrawFace = -1,

        kBoth_DrawFace,
        kCCW_DrawFace,
        kCW_DrawFace,
    };

    /**
     * Gets whether the target is drawing clockwise, counterclockwise,
     * or both faces.
     * @return the current draw face(s).
     */
    DrawFace getDrawFace() const { return fDrawFace; }

    /**
     * Controls whether clockwise, counterclockwise, or both faces are drawn.
     * @param face  the face(s) to draw.
     */
    void setDrawFace(DrawFace face) {
        SkASSERT(kInvalid_DrawFace != face);
        fDrawFace = face;
    }

    /// @}

    ///////////////////////////////////////////////////////////////////////////

    bool usePLSDstRead(const GrDrawBatch* batch) const;

private:
    // Some of the auto restore objects assume that no effects are removed during their lifetime.
    // This is used to assert that this condition holds.
    SkDEBUGCODE(mutable int fBlockEffectRemovalCnt;)

    typedef SkSTArray<4, const GrFragmentProcessor*, true> FragmentProcessorArray;

    uint32_t                                fFlags;
    const GrUserStencilSettings*            fUserStencilSettings;
    DrawFace                                fDrawFace;
    mutable SkAutoTUnref<const GrXPFactory> fXPFactory;
    FragmentProcessorArray                  fColorFragmentProcessors;
    FragmentProcessorArray                  fCoverageFragmentProcessors;

    friend class GrPipeline;
    friend class GrDrawTarget;
};

#endif