WaterManager.h

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/* Copyright (C) 2023 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/>.
 */

/*
 * Water settings (speed, height) and texture management
 */

#ifndef INCLUDED_WATERMANAGER
#define INCLUDED_WATERMANAGER

#include "graphics/Color.h"
#include "graphics/Texture.h"
#include "maths/Matrix3D.h"
#include "maths/Vector2D.h"
#include "renderer/backend/IDeviceCommandContext.h"
#include "renderer/backend/IFramebuffer.h"
#include "renderer/backend/IShaderProgram.h"
#include "renderer/backend/ITexture.h"
#include "renderer/VertexBufferManager.h"

#include <memory>
#include <vector>

class CFrustum;

struct WaveObject;

/**
 * Class WaterManager: Maintain rendering-related water settings and textures
 * Anything that affects gameplay should go in CcmpWaterManager.cpp and passed to this (possibly as copy).
 */

class WaterManager
{
public:
    CTexturePtr m_WaterTexture[60];
    CTexturePtr m_NormalMap[60];

    // How strong the waves are at point X. % of waviness.
    std::unique_ptr<float[]> m_WindStrength;
    // How far from the shore a point is. Manhattan.
    std::unique_ptr<float[]> m_DistanceHeightmap;

    // Waves vertex buffers
    // TODO: measure storing value instead of pointer.
    std::vector<std::unique_ptr<WaveObject>> m_ShoreWaves;
    // Waves indices buffer. Only one since All Wave Objects have the same.
    CVertexBufferManager::Handle m_ShoreWavesVBIndices;

    Renderer::Backend::IVertexInputLayout* m_ShoreVertexInputLayout = nullptr;

    size_t m_MapSize;
    ssize_t m_TexSize;

    CTexturePtr m_WaveTex;
    CTexturePtr m_FoamTex;

    std::unique_ptr<Renderer::Backend::ITexture> m_FancyTexture;
    std::unique_ptr<Renderer::Backend::ITexture> m_FancyTextureDepth;
    std::unique_ptr<Renderer::Backend::ITexture> m_ReflFboDepthTexture;
    std::unique_ptr<Renderer::Backend::ITexture> m_RefrFboDepthTexture;

    // used to know what to update when updating parts of the terrain only.
    u32 m_updatei0;
    u32 m_updatej0;
    u32 m_updatei1;
    u32 m_updatej1;

    bool m_RenderWater;

    // If disabled, force the use of the simple water shader for rendering.
    bool m_WaterEffects;
    // Those variables register the current quality level. If there is a change, I have to recompile the shader.
    // Use real depth or use the fake precomputed one.
    bool m_WaterRealDepth;
    // Use fancy shore effects and show trails behind ships
    bool m_WaterFancyEffects;
    // Use refractions instead of simply making the water more or less transparent.
    bool m_WaterRefraction;
    // Use complete reflections instead of showing merely the sky.
    bool m_WaterReflection;

    bool m_NeedsReloading;
    // requires also recreating the super fancy information.
    bool m_NeedInfoUpdate;

    float m_WaterHeight;

    double m_WaterTexTimer;
    float m_RepeatPeriod;

    // Reflection and refraction textures for fancy water
    std::unique_ptr<Renderer::Backend::ITexture> m_ReflectionTexture;
    std::unique_ptr<Renderer::Backend::ITexture> m_RefractionTexture;
    size_t m_RefTextureSize;

    // framebuffer objects
    std::unique_ptr<Renderer::Backend::IFramebuffer> m_RefractionFramebuffer;
    std::unique_ptr<Renderer::Backend::IFramebuffer> m_ReflectionFramebuffer;
    std::unique_ptr<Renderer::Backend::IFramebuffer> m_FancyEffectsFramebuffer;
    std::unique_ptr<Renderer::Backend::IFramebuffer> m_FancyEffectsOccludersFramebuffer;

    // Model-view-projection matrices for reflected & refracted cameras
    // (used to let the vertex shader do projective texturing)
    CMatrix3D m_ReflectionMatrix;
    CMatrix3D m_RefractionMatrix;
    CMatrix3D m_RefractionProjInvMatrix;
    CMatrix3D m_RefractionViewInvMatrix;

    // Water parameters
    std::wstring m_WaterType;       // Which texture to use.
    CColor m_WaterColor;    // Color of the water without refractions. This is what you're seeing when the water's deep or murkiness high.
    CColor m_WaterTint;     // Tint of refraction in the water.
    float m_Waviness;       // How big the waves are.
    float m_Murkiness;      // How murky the water is.
    float m_WindAngle;  // In which direction the water waves go.

public:
    WaterManager();
    ~WaterManager();

    void Initialize();

    /**
     * LoadWaterTextures: Load water textures from within the
     * progressive load framework.
     *
     * @return 0 if loading has completed, a value from 1 to 100 (in percent of completion)
     * if more textures need to be loaded and a negative error value on failure.
     */
    int LoadWaterTextures();

    /**
     * Recreates/loads needed water textures.
     */
    void RecreateOrLoadTexturesIfNeeded();

    /**
     * ReloadWaterNormalTextures: Reload the normal textures so that changing
     * water type in Atlas will actually do the right thing.
     */
    void ReloadWaterNormalTextures();

    /**
     * UnloadWaterTextures: Free any loaded water textures and reset the internal state
     * so that another call to LoadWaterTextures will begin progressive loading.
     */
    void UnloadWaterTextures();

    /**
     * RecomputeWaterData: calculates all derived data from the waterheight
     */
    void RecomputeWaterData();

    /**
     * RecomputeWindStrength: calculates the intensity of waves
     */
    void RecomputeWindStrength();

    /**
     * RecomputeDistanceHeightmap: recalculates (or calculates) the distance heightmap.
     */
    void RecomputeDistanceHeightmap();

    /**
     * CreateWaveMeshes: Creates the waves objects (and meshes).
     */
    void CreateWaveMeshes();

    /**
     * Updates the map size. Will trigger a complete recalculation of fancy water information the next turn.
     */
    void SetMapSize(size_t size);

    /**
     * Updates the settings to the one from the renderer, and sets m_NeedsReloading.
     */
    void UpdateQuality();

    /**
     * Returns true if fancy water shaders will be used (i.e. the hardware is capable
     * and it hasn't been configured off)
     */
    bool WillRenderFancyWater() const;

    void RenderWaves(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CFrustum& frustrum);

    /**
     * Returns an index of the current texture that should be used for rendering
     * water.
     */
    size_t GetCurrentTextureIndex(const double& period) const;
    size_t GetNextTextureIndex(const double& period) const;
};


#endif // INCLUDED_WATERMANAGER