gfx_driver_base.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

//=============================================================================
//
// Implementation base for graphics driver
//
//=============================================================================

#ifndef AGS_ENGINE_GFX_GFX_DRIVER_BASE_H
#define AGS_ENGINE_GFX_GFX_DRIVER_BASE_H

#include "common/std/memory.h"
#include "common/std/map.h"
#include "common/std/vector.h"
#include "ags/engine/gfx/ddb.h"
#include "ags/shared/gfx/gfx_def.h"
#include "ags/engine/gfx/graphics_driver.h"
#include "ags/shared/util/scaling.h"

namespace AGS3 {
namespace AGS {
namespace Engine {

using Shared::Bitmap;
using Shared::PlaneScaling;

// Sprite batch, defines viewport and an optional model transformation for the list of sprites
struct SpriteBatchDesc {
    uint32_t                 Parent = UINT32_MAX;
    // View rectangle for positioning and clipping, in resolution coordinates
    // (this may be screen or game frame resolution, depending on circumstances)
    Rect                     Viewport;
    // Optional model transformation, to be applied to each sprite
    SpriteTransform          Transform;
    // Optional flip, applied to the whole batch as the last transform
    Shared::GraphicFlip      Flip = Shared::kFlip_None;
    // Optional bitmap to draw sprites upon. Used exclusively by the software rendering mode.
    PBitmap                  Surface;

    SpriteBatchDesc() = default;
    SpriteBatchDesc(uint32_t parent, const Rect viewport, const SpriteTransform & transform,
        Shared::GraphicFlip flip = Shared::kFlip_None, PBitmap surface = nullptr)
        : Parent(parent)
        , Viewport(viewport)
        , Transform(transform)
        , Flip(flip)
        , Surface(surface) {
    }
};

typedef std::vector<SpriteBatchDesc> SpriteBatchDescs;

// The single sprite entry in the render list
template<class T_DDB>
struct SpriteDrawListEntry {
    T_DDB *ddb = nullptr; // TODO: use shared pointer?
    uint32_t node = 0; // sprite batch / scene node index
    int x = 0, y = 0; // sprite position, in local batch / node coordinates
    bool skip = false;

    SpriteDrawListEntry() = default;
    SpriteDrawListEntry(T_DDB * ddb_, uint32_t node_, int x_, int y_)
        : ddb(ddb_)
        , node(node_)
        , x(x_)
        , y(y_)
        , skip(false) {
    }
};


// GraphicsDriverBase - is the parent class for all graphics drivers in AGS,
// that incapsulates the most common functionality.
class GraphicsDriverBase : public IGraphicsDriver {
public:
    GraphicsDriverBase();

    bool        IsModeSet() const override;
    bool        IsNativeSizeValid() const override;
    bool        IsRenderFrameValid() const override;
    DisplayMode GetDisplayMode() const override;
    Size        GetNativeSize() const override;
    Rect        GetRenderDestination() const override;

    bool        SetVsync(bool enabled) override;
    bool        GetVsync() const override;

    void        BeginSpriteBatch(const Rect &viewport, const SpriteTransform &transform,
                                 Shared::GraphicFlip flip = Shared::kFlip_None, PBitmap surface = nullptr) override;
    void        EndSpriteBatch() override;
    void        ClearDrawLists() override;

    void        SetCallbackForPolling(GFXDRV_CLIENTCALLBACK callback) override {
        _pollingCallback = callback;
    }
    void        SetCallbackToDrawScreen(GFXDRV_CLIENTCALLBACK callback, GFXDRV_CLIENTCALLBACK post_callback) override {
        _drawScreenCallback = callback;
        _drawPostScreenCallback = post_callback;
    }
    void        SetCallbackOnInit(GFXDRV_CLIENTCALLBACKINITGFX callback) override {
        _initGfxCallback = callback;
    }
    void        SetCallbackOnSpriteEvt(GFXDRV_CLIENTCALLBACKEVT callback) override {
        _spriteEvtCallback = callback;
    }

protected:
    // Special internal values, applied to DrawListEntry
    static const intptr_t DRAWENTRY_STAGECALLBACK = 0x0;
    static const intptr_t DRAWENTRY_FADE = 0x1;
    static const intptr_t DRAWENTRY_TINT = 0x2;

    // Called after graphics driver was initialized for use for the first time
    virtual void OnInit();
    // Called just before graphics mode is going to be uninitialized and its
    // resources released
    virtual void OnUnInit();
    // Called after new mode was successfully initialized
    virtual void OnModeSet(const DisplayMode &mode);
    // Called when the new native size is set
    virtual void OnSetNativeRes(const GraphicResolution &native_res);
    // Called before display mode is going to be released
    virtual void OnModeReleased();
    // Called when new render frame is set
    virtual void OnSetRenderFrame(const Rect &dst_rect);
    // Called when the new filter is set
    virtual void OnSetFilter();

    // Try changing vsync setting; fills new current mode in vsync_res,
    // returns whether the new setting was set successfully.
    virtual bool SetVsyncImpl(bool vsync, bool &vsync_res) { return false; }

    // Initialize sprite batch and allocate necessary resources
    virtual void InitSpriteBatch(size_t index, const SpriteBatchDesc &desc) = 0;
    // Gets the index of a last draw entry (sprite)
    virtual size_t GetLastDrawEntryIndex() = 0;
    // Clears sprite lists
    virtual void ResetAllBatches() = 0;

    void         OnScalingChanged();

    DisplayMode         _mode;          // display mode settings
    Rect                _srcRect;       // rendering source rect
    int                 _srcColorDepth; // rendering source color depth (in bits per pixel)
    Rect                _dstRect;       // rendering destination rect
    Rect                _filterRect;    // filter scaling destination rect (before final scaling)
    PlaneScaling        _scaling;       // native -> render dest coordinate transformation

    // Capability flags
    bool                _capsVsync = false; // is vsync available

    // Callbacks
    GFXDRV_CLIENTCALLBACK _pollingCallback;
    GFXDRV_CLIENTCALLBACK _drawScreenCallback;
    GFXDRV_CLIENTCALLBACK _drawPostScreenCallback;
    GFXDRV_CLIENTCALLBACKEVT _spriteEvtCallback;
    GFXDRV_CLIENTCALLBACKINITGFX _initGfxCallback;

    // Sprite batch parameters
    SpriteBatchDescs _spriteBatchDesc;
    // The range of sprites in this sprite batch (counting nested sprites):
    // the last of the previous batch, and the last of the current.
    std::vector<std::pair<size_t, size_t>> _spriteBatchRange;
    // The index of a currently filled sprite batch
    size_t _actSpriteBatch;
    // The index of a currently rendered sprite batch
    // (or -1 / UINT32_MAX if we are outside of the render pass)
    uint32_t _rendSpriteBatch;
};




// Parent class for the video memory DDBs
class BaseDDB : public IDriverDependantBitmap {
public:
    int GetWidth() const override {
        return _width;
    }
    int GetHeight() const override {
        return _height;
    }
    int GetColorDepth() const override {
        return _colDepth;
    }

    int _width = 0, _height = 0;
    int _colDepth = 0;
    bool _hasAlpha = false; // has meaningful alpha channel
    bool _opaque = false;   // no mask color

protected:
    BaseDDB() {}
    virtual ~BaseDDB() {}
};

// A base parent for the otherwise opaque texture data object;
// TextureData refers to the pixel data itself, with no additional
// properties. It may be shared between multiple sprites if necessary.
struct TextureData {
    uint32_t ID = UINT32_MAX;
    bool RenderTarget = false; // replace with flags later
    virtual ~TextureData() = default;
protected:
    TextureData() = default;
};

// Generic TextureTile base
struct TextureTile {
    int x = 0, y = 0;
    int width = 0, height = 0;
};


// VideoMemoryGraphicsDriver - is the parent class for the graphic drivers
// which drawing method is based on passing the sprite stack into GPU,
// rather than blitting to flat screen bitmap.
class VideoMemoryGraphicsDriver : public GraphicsDriverBase {
public:
    VideoMemoryGraphicsDriver();
    ~VideoMemoryGraphicsDriver() override;

    bool UsesMemoryBackBuffer() override;
    Bitmap *GetMemoryBackBuffer() override;
    void SetMemoryBackBuffer(Bitmap *backBuffer) override;
    Bitmap *GetStageBackBuffer(bool mark_dirty) override;
    void SetStageBackBuffer(Bitmap *backBuffer) override;
    bool GetStageMatrixes(RenderMatrixes &rm) override;
    // Creates new texture using given parameters
    IDriverDependantBitmap *CreateDDB(int width, int height, int color_depth, bool opaque) override = 0;
    // Creates new texture and copy bitmap contents over
    IDriverDependantBitmap *CreateDDBFromBitmap(Bitmap *bitmap, bool hasAlpha, bool opaque = false) override;
    // Get shared texture from cache, or create from bitmap and assign ID
    IDriverDependantBitmap *GetSharedDDB(uint32_t sprite_id, Bitmap *bitmap, bool hasAlpha, bool opaque) override;
    // Removes the shared texture reference, will force the texture to recreate next time
    void ClearSharedDDB(uint32_t sprite_id) override;
    // Updates shared texture data, but only if it is present in the cache
    void UpdateSharedDDB(uint32_t sprite_id, Bitmap *bitmap, bool hasAlpha, bool opaque) override;
    void DestroyDDB(IDriverDependantBitmap* ddb) override;

    // Sets stage screen parameters for the current batch.
    void SetStageScreen(const Size &sz, int x = 0, int y = 0) override;

protected:
    // Create texture data with the given parameters
    virtual TextureData *CreateTextureData(int width, int height, bool opaque, bool as_render_target = false) = 0;
    // Update texture data from the given bitmap
    virtual void UpdateTextureData(TextureData *txdata, Bitmap *bmp, bool opaque, bool hasAlpha) = 0;
    // Create DDB using preexisting texture data
    virtual IDriverDependantBitmap *CreateDDB(std::shared_ptr<TextureData> txdata,
          int width, int height, int color_depth, bool opaque) = 0;
    // Retrieve shared texture data object from the given DDB
    virtual std::shared_ptr<TextureData> GetTextureData(IDriverDependantBitmap *ddb) = 0;
    virtual void DestroyDDBImpl(IDriverDependantBitmap* ddb) = 0;

    // Stage screens are raw bitmap buffers meant to be sent to plugins on demand
    // at certain drawing stages. If used at least once these buffers are then
    // rendered as additional sprites in their respected order.
    // Presets a stage screen with the given position (size is obligatory, offsets not).
    void SetStageScreen(size_t index, const Size &sz, int x = 0, int y = 0);
    // Returns a raw bitmap for the given stage screen.
    Bitmap *GetStageScreenRaw(size_t index);
    // Updates and returns a DDB for the given stage screen, and optional x,y position;
    // clears the raw bitmap after copying to the texture.
    IDriverDependantBitmap *UpdateStageScreenDDB(size_t index, int &x, int &y);
    // Disposes all the stage screen raw bitmaps and DDBs.
    void DestroyAllStageScreens();
    // Use engine callback to pass a render event;
    // returns a DDB if anything was drawn onto the current stage screen
    // (in which case it also fills optional x,y position),
    // or nullptr if this entry should be skipped.
    IDriverDependantBitmap *DoSpriteEvtCallback(int evt, int data, int &x, int &y);

    // Prepare and get fx item from the pool
    IDriverDependantBitmap *MakeFx(int r, int g, int b);
    // Resets fx pool counter
    void ResetFxPool();
    // Disposes all items in the fx pool
    void DestroyFxPool();

    // Prepares bitmap to be applied to the texture, copies pixels to the provided buffer
    void BitmapToVideoMem(const Bitmap *bitmap, const bool has_alpha, const TextureTile *tile,
        char *dst_ptr, const int dst_pitch, const bool usingLinearFiltering);
    // Same but optimized for opaque source bitmaps which ignore transparent "mask color"
    void BitmapToVideoMemOpaque(const Bitmap *bitmap, const bool has_alpha, const TextureTile *tile,
        char *dst_ptr, const int dst_pitch);

    // Stage virtual screen is used to let plugins draw custom graphics
    // in between render stages (between room and GUI, after GUI, and so on)
    PBitmap _stageVirtualScreen;
    IDriverDependantBitmap *_stageVirtualScreenDDB;
    // Stage matrixes are used to let plugins with hardware acceleration know model matrix;
    // these matrixes are filled compatible with each given renderer
    RenderMatrixes _stageMatrixes;

    // Color component shifts in video bitmap format (set by implementations)
    int _vmem_a_shift_32;
    int _vmem_r_shift_32;
    int _vmem_g_shift_32;
    int _vmem_b_shift_32;

private:
    // Stage virtual screens are used to let plugins draw custom graphics
    // in between render stages (between room and GUI, after GUI, and so on).
    // TODO: possibly may be optimized further by having only 1 bitmap/ddb
    // pair, and subbitmaps for raw drawing on separate stages.
    struct StageScreen {
        Rect Position; // bitmap size and pos preset (bitmap may be created later)
        std::unique_ptr<Bitmap> Raw;
        IDriverDependantBitmap *DDB = nullptr;
    };
    std::vector<StageScreen> _stageScreens;
    // Flag which indicates whether stage screen was drawn upon during engine
    // callback and has to be inserted into sprite stack.
    bool _stageScreenDirty;

    // Fx quads pool (for screen overlay effects)
    struct ScreenFx {
        Bitmap *Raw = nullptr;
        IDriverDependantBitmap *DDB = nullptr;
        int Red = -1;
        int Green = -1;
        int Blue = -1;
    };
    std::vector<ScreenFx> _fxPool;
    size_t _fxIndex; // next free pool item

    // Texture short-term cache:
    // - caches textures while they are in the immediate use;
    // - this lets to share same texture data among multiple sprites on screen.
    // TextureCacheItem stores weak references to the existing texture tiles,
    // identified by an arbitrary uint32 number.
    // TODO: a curious topic to consider: reuse released TextureData for
    // textures of the same size (research potential performance impact).
    struct TextureCacheItem {
        GraphicResolution Res;
        std::weak_ptr<TextureData> Data;
        TextureCacheItem() = default;
        TextureCacheItem(std::shared_ptr<TextureData> data, const GraphicResolution &res)
            : Data(data), Res(res) {}
    };
    std::unordered_map<uint32_t, TextureCacheItem> _txRefs;
};

} // namespace Engine
} // namespace AGS
} // namespace AGS3

#endif