SceneRenderer.h

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/* Copyright (C) 2022 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_RENDERER_SCENERENDERER
#define INCLUDED_RENDERER_SCENERENDERER

#include "graphics/Camera.h"
#include "graphics/ShaderDefines.h"
#include "graphics/ShaderProgramPtr.h"
#include "maths/BoundingBoxAligned.h"
#include "ps/Singleton.h"
#include "renderer/backend/IDeviceCommandContext.h"
#include "renderer/RenderingOptions.h"
#include "renderer/Scene.h"

#include <memory>

class CCanvas2D;
class CLightEnv;
class CMaterial;
class CMaterialManager;
class CModel;
class CParticleManager;
class CPatch;
class CSimulation2;
class ShadowMap;
class SkyManager;
class TerrainRenderer;
class WaterManager;

// rendering modes
enum ERenderMode { WIREFRAME, SOLID, EDGED_FACES };

// transparency modes
enum ETransparentMode { TRANSPARENT, TRANSPARENT_OPAQUE, TRANSPARENT_BLEND };

class CSceneRenderer : public SceneCollector
{
public:
    enum CullGroup
    {
        CULL_DEFAULT,
        CULL_SHADOWS_CASCADE_0,
        CULL_SHADOWS_CASCADE_1,
        CULL_SHADOWS_CASCADE_2,
        CULL_SHADOWS_CASCADE_3,
        CULL_REFLECTIONS,
        CULL_REFRACTIONS,
        CULL_SILHOUETTE_OCCLUDER,
        CULL_SILHOUETTE_CASTER,
        CULL_MAX
    };

    CSceneRenderer();
    ~CSceneRenderer();

    void Initialize();
    void Resize(int width, int height);

    void BeginFrame();
    void EndFrame();

    /**
     * Set simulation context for rendering purposes.
     * Must be called at least once when the game has started and before
     * frames are rendered.
     */
    void SetSimulation(CSimulation2* simulation);

    // trigger a reload of shaders (when parameters they depend on have changed)
    void MakeShadersDirty();

    /**
     * Set up the camera used for rendering the next scene; this includes
     * setting OpenGL state like viewport, projection and modelview matrices.
     *
     * @param viewCamera this camera determines the eye position for rendering
     * @param cullCamera this camera determines the frustum for culling in the renderer and
     * for shadow calculations
     */
    void SetSceneCamera(const CCamera& viewCamera, const CCamera& cullCamera);

    /**
     * Enumerate and submit all objects of the given scene which should be rendered.
     * Must be called before RenderScene.
     */
    void PrepareScene(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext, Scene& scene);

    /**
     * Render submitted objects of the previously given scene.
     */
    void RenderScene(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext);

    /**
     * Render overlays of the previously given scene.
     * Must be called after RenderScene.
     */
    void RenderSceneOverlays(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext);

    /**
     * Return the scene that is currently being rendered.
     * Only valid when the renderer is in a RenderScene call.
     */
    Scene& GetScene();

    /**
     * Render text overlays on top of the scene.
     * Assumes the caller has set up the GL environment for orthographic rendering
     * with texturing and blending.
     */
    void RenderTextOverlays(CCanvas2D& canvas);

    // set the current lighting environment; (note: the passed pointer is just copied to a variable within the renderer,
    // so the lightenv passed must be scoped such that it is not destructed until after the renderer is no longer rendering)
    void SetLightEnv(CLightEnv* lightenv)
    {
        m_LightEnv = lightenv;
    }

    // set the mode to render subsequent terrain patches
    void SetTerrainRenderMode(ERenderMode mode) { m_TerrainRenderMode = mode; }
    // get the mode to render subsequent terrain patches
    ERenderMode GetTerrainRenderMode() const { return m_TerrainRenderMode; }

    // set the mode to render subsequent water patches
    void SetWaterRenderMode(ERenderMode mode) { m_WaterRenderMode = mode; }
    // get the mode to render subsequent water patches
    ERenderMode GetWaterRenderMode() const { return m_WaterRenderMode; }

    // set the mode to render subsequent models
    void SetModelRenderMode(ERenderMode mode) { m_ModelRenderMode = mode; }
    // get the mode to render subsequent models
    ERenderMode GetModelRenderMode() const { return m_ModelRenderMode; }

    // Get the mode to render subsequent overlays.
    ERenderMode GetOverlayRenderMode() const { return m_OverlayRenderMode; }
    // Set the mode to render subsequent overlays.
    void SetOverlayRenderMode(ERenderMode mode) { m_OverlayRenderMode = mode; }

    // debugging
    void SetDisplayTerrainPriorities(bool enabled) { m_DisplayTerrainPriorities = enabled; }

    // return the current light environment
    const CLightEnv &GetLightEnv() { return *m_LightEnv; }

    // return the current view camera
    const CCamera& GetViewCamera() const { return m_ViewCamera; }
    // replace the current view camera
    void SetViewCamera(const CCamera& camera) { m_ViewCamera = camera; }

    // return the current cull camera
    const CCamera& GetCullCamera() const { return m_CullCamera; }

    /**
     * GetWaterManager: Return the renderer's water manager.
     *
     * @return the WaterManager object used by the renderer
     */
    WaterManager& GetWaterManager();

    /**
     * GetSkyManager: Return the renderer's sky manager.
     *
     * @return the SkyManager object used by the renderer
     */
    SkyManager& GetSkyManager();

    CParticleManager& GetParticleManager();

    TerrainRenderer& GetTerrainRenderer();

    CMaterialManager& GetMaterialManager();

    ShadowMap& GetShadowMap();

    /**
     * Resets the render state to default, that was before a game started
     */
    void ResetState();

    void ReloadShaders();

protected:
    void Submit(CPatch* patch) override;
    void Submit(SOverlayLine* overlay) override;
    void Submit(SOverlayTexturedLine* overlay) override;
    void Submit(SOverlaySprite* overlay) override;
    void Submit(SOverlayQuad* overlay) override;
    void Submit(CModelDecal* decal) override;
    void Submit(CParticleEmitter* emitter) override;
    void Submit(SOverlaySphere* overlay) override;
    void SubmitNonRecursive(CModel* model) override;

    /**
     * Update and upload all needed data for submitted objects.
     */
    void PrepareSubmissions(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CBoundingBoxAligned& waterScissor);

    // render any batched objects
    void RenderSubmissions(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CBoundingBoxAligned& waterScissor);

    // patch rendering stuff
    void RenderPatches(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context, int cullGroup);

    // model rendering stuff
    void RenderModels(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context, int cullGroup);
    void RenderTransparentModels(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context, int cullGroup, ETransparentMode transparentMode);

    void RenderSilhouettes(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context);

    void RenderParticles(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        int cullGroup);

    // shadow rendering stuff
    void RenderShadowMap(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context);

    // render water reflection and refraction textures
    void RenderReflections(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context, const CBoundingBoxAligned& scissor);
    void RenderRefractions(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        const CShaderDefines& context, const CBoundingBoxAligned& scissor);

    void ComputeReflectionCamera(CCamera& camera, const CBoundingBoxAligned& scissor) const;
    void ComputeRefractionCamera(CCamera& camera, const CBoundingBoxAligned& scissor) const;

    // debugging
    void DisplayFrustum();

    // enable oblique frustum clipping with the given clip plane
    void SetObliqueFrustumClipping(CCamera& camera, const CVector4D& clipPlane) const;

    // Private data that is not needed by inline functions.
    class Internals;
    std::unique_ptr<Internals> m;

    // Current terrain rendering mode.
    ERenderMode m_TerrainRenderMode;
    // Current water rendering mode.
    ERenderMode m_WaterRenderMode;
    // Current model rendering mode.
    ERenderMode m_ModelRenderMode;
    // Current overlay rendering mode.
    ERenderMode m_OverlayRenderMode;

    /**
     * m_ViewCamera: determines the eye position for rendering
     *
     * @see CGameView::m_ViewCamera
     */
    CCamera m_ViewCamera;

    /**
     * m_CullCamera: determines the frustum for culling and shadowmap calculations
     *
     * @see CGameView::m_ViewCamera
     */
    CCamera m_CullCamera;

    // only valid inside a call to RenderScene
    Scene* m_CurrentScene;
    int m_CurrentCullGroup;

    CBoundingBoxAligned m_WaterScissor;

    // current lighting setup
    CLightEnv* m_LightEnv;

    /**
     * Enable rendering of terrain tile priority text overlay, for debugging.
     */
    bool m_DisplayTerrainPriorities;
};

#endif // INCLUDED_RENDERER_SCENERENDERER