ObjectBase.h

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/* Copyright (C) 2021 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_OBJECTBASE
#define INCLUDED_OBJECTBASE

#include "lib/file/vfs/vfs_path.h"
#include "ps/CStr.h"
#include "ps/CStrIntern.h"

class CActorDef;
class CObjectEntry;
class CObjectManager;
class CXeromyces;
class XMBElement;

#include <boost/random/mersenne_twister.hpp>
#include <map>
#include <memory>
#include <set>
#include <unordered_set>
#include <vector>

/**
 * Maintains the tree of possible objects from a specific actor definition at a given quality level.
 * An Object Base is made of:
 *  - a material
 *  - a few properties (float on water / casts shadow / ...)
 *  - a number of variant groups.
 * Any actual object in game will pick a variant from each group (see ObjectEntry).
 */
class CObjectBase
{
    friend CActorDef;

    // See CopyWithQuality() below.
    NONCOPYABLE(CObjectBase);
public:
    struct Anim
    {
        // constructor
        Anim() : m_Frequency(0), m_Speed(1.f), m_ActionPos(-1.f), m_ActionPos2(-1.f), m_SoundPos(-1.f) {}
        // name of the animation - "Idle", "Run", etc
        CStr m_AnimName;
        // ID of the animation: if not empty, something specific to sync with props.
        CStr m_ID = "";
        int m_Frequency;
        // filename of the animation - manidle.psa, manrun.psa, etc
        VfsPath m_FileName;
        // animation speed, as specified in XML actor file
        float m_Speed;
        // fraction [0.0, 1.0] of the way through the animation that the interesting bit(s)
        // happens, or -1.0 if unspecified
        float m_ActionPos;
        float m_ActionPos2;
        float m_SoundPos;
    };

    struct Prop
    {
        // constructor
        Prop() : m_minHeight(0.f), m_maxHeight(0.f), m_selectable(true) {}
        // name of the prop point to attach to - "Prop01", "Prop02", "Head", "LeftHand", etc ..
        CStr m_PropPointName;
        // name of the model file - art/actors/props/sword.xml or whatever
        CStrW m_ModelName;
        // allow the prop to ajust the height from minHeight to maxHeight relative to the main model
        float m_minHeight;
        float m_maxHeight;
        bool m_selectable;
    };

    struct Samp
    {
        // identifier name of sampler in GLSL shaders
        CStrIntern m_SamplerName;
        // path to load from
        VfsPath m_SamplerFile;
    };

    struct Decal
    {
        Decal() : m_SizeX(0.f), m_SizeZ(0.f), m_Angle(0.f), m_OffsetX(0.f), m_OffsetZ(0.f) {}

        float m_SizeX;
        float m_SizeZ;
        float m_Angle;
        float m_OffsetX;
        float m_OffsetZ;
    };

    struct Variant
    {
        Variant() : m_Frequency(0) {}

        CStr m_VariantName; // lowercase name
        int m_Frequency;
        VfsPath m_ModelFilename;
        Decal m_Decal;
        VfsPath m_Particles;
        CStr m_Color;

        std::vector<Anim> m_Anims;
        std::vector<Prop> m_Props;
        std::vector<Samp> m_Samplers;
    };

    struct Variation
    {
        VfsPath model;
        Decal decal;
        VfsPath particles;
        CStr color;
        std::multimap<CStr, Prop> props;
        std::multimap<CStr, Anim> anims;
        std::multimap<CStr, Samp> samplers;
    };

    CObjectBase(CObjectManager& objectManager, CActorDef& actorDef, u8 QualityLevel);

    // Returns a set of selection such that, added to initialSelections, CalculateVariationKey can proceed.
    std::set<CStr> CalculateRandomRemainingSelections(uint32_t seed, const std::vector<std::set<CStr>>& initialSelections) const;

    // Get the variation key (indices of chosen variants from each group)
    // based on the selection strings.
    // Should not have to make a random choice: the selections should be complete.
    std::vector<u8> CalculateVariationKey(const std::vector<const std::set<CStr>*>& selections) const;

    // Get the final actor data, combining all selected variants
    const Variation BuildVariation(const std::vector<u8>& variationKey) const;

    // Get a list of variant groups for this object, plus for all possible
    // props. Duplicated groups are removed, if several props share the same
    // variant names.
    std::vector<std::vector<CStr> > GetVariantGroups() const;

    // Return a string identifying this actor uniquely (includes quality level information);
    const CStr& GetIdentifier() const;

    /**
     * Returns whether this object (including any possible props)
     * uses the given file. (This is used for hotloading.)
     */
    bool UsesFile(const VfsPath& pathname) const;


    struct {
        // cast shadows from this object
        bool m_CastShadows;
        // float on top of water
        bool m_FloatOnWater;
    } m_Properties;

    // the material file
    VfsPath m_Material;

    // Quality level - part of the data resource path.
    u8 m_QualityLevel;

private:
    // Private interface for CActorDef/ObjectEntry

    /**
     * Acts as an explicit copy constructor, for a new quality level.
     * Note that this does not reload the actor, so this setting will only change props.
     */
    std::unique_ptr<CObjectBase> CopyWithQuality(u8 newQualityLevel) const;

    // A low-quality RNG like rand48 causes visible non-random patterns (particularly
    // in large grids of the same actor with consecutive seeds, e.g. forests),
    // so use a better one that appears to avoid those patterns
    using rng_t = boost::mt19937;
    std::set<CStr> CalculateRandomRemainingSelections(rng_t& rng, const std::vector<std::set<CStr>>& initialSelections) const;

    /**
     * Get all quality levels at which this object changes (includes props).
     * Intended to be called by CActorFef.
     * @param splits - a sorted vector of unique quality splits.
     */
    void GetQualitySplits(std::vector<u8>& splits) const;

    [[nodiscard]] bool Load(const CXeromyces& XeroFile, const XMBElement& base);
    [[nodiscard]] bool LoadVariant(const CXeromyces& XeroFile, const XMBElement& variant, Variant& currentVariant);

private:
    // Backref to the owning actor.
    CActorDef& m_ActorDef;

    // Used to identify this actor uniquely in the ObjectManager (and for debug).
    CStr m_Identifier;

    std::vector< std::vector<Variant> > m_VariantGroups;
    CObjectManager& m_ObjectManager;
};

/**
 * Represents an actor file. Actors can contain various quality levels.
 * An ActorDef maintains a CObjectBase for each specified quality level, and provides access to it.
 */
class CActorDef
{
    // Friend these three so they can use GetBase.
    friend class CObjectManager;
    friend class CObjectBase;
    friend class CObjectEntry;

    NONCOPYABLE(CActorDef);
public:

    CActorDef(CObjectManager& objectManager);

    std::vector<u8> QualityLevels() const;

    VfsPath GetPathname() const { return m_Pathname; }

    /**
     * Return a list of selections specifying a particular variant in all groups, based on the seed.
     */
    std::set<CStr> PickSelectionsAtRandom(uint32_t seed) const;

// Interface accessible from CObjectManager / CObjectBase
protected:
    /**
     * Return the Object base matching the given quality level.
     */
    const std::shared_ptr<CObjectBase>& GetBase(u8 QualityLevel) const;

    /**
     * Initialise this object by loading from the given file.
     * Returns false on error.
     */
    bool Load(const VfsPath& pathname);

    /**
     * Initialise this object with a default placeholder actor,
     * pretending to be the actor at pathname.
     */
    void LoadErrorPlaceholder(const VfsPath& pathname);

    /**
     * Returns whether this actor (including any possible props)
     * uses the given file. (This is used for hotloading.)
     */
    bool UsesFile(const VfsPath& pathname) const;

    // filename that this was loaded from
    VfsPath m_Pathname;

private:
    CObjectManager& m_ObjectManager;

    // std::shared_ptr to avoid issues during hotloading.
    std::vector<std::shared_ptr<CObjectBase>> m_ObjectBases;

    std::unordered_set<VfsPath> m_UsedFiles;
};

#endif