LOSTexture.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/>.
 */
 
#ifndef INCLUDED_LOSTEXTURE
#define INCLUDED_LOSTEXTURE
 
#include "graphics/ShaderTechniquePtr.h"
#include "maths/Matrix3D.h"
#include "renderer/backend/Format.h"
#include "renderer/backend/IDeviceCommandContext.h"
#include "renderer/backend/IFramebuffer.h"
#include "renderer/backend/IShaderProgram.h"
#include "renderer/backend/ITexture.h"
 
#include <memory>
 
class CLosQuerier;
class CSimulation2;
 
/**
 * Maintains the LOS (fog-of-war / shroud-of-darkness) texture, used for
 * rendering and for the minimap.
 */
class CLOSTexture
{
    NONCOPYABLE(CLOSTexture);
    friend class TestLOSTexture;
 
public:
    CLOSTexture(CSimulation2& simulation);
    ~CLOSTexture();
 
    /**
     * Marks the LOS texture as needing recomputation. Call this after each
     * simulation update, to ensure responsive updates.
     */
    void MakeDirty();
 
    /**
     * Recomputes the LOS texture if necessary, and returns the texture handle.
     * Also potentially switches the current active texture unit, and enables texturing on it.
     * The texture is in 8-bit ALPHA format.
     */
    Renderer::Backend::ITexture* GetTexture();
    Renderer::Backend::ITexture* GetTextureSmooth();
 
    void InterpolateLOS(Renderer::Backend::IDeviceCommandContext* deviceCommandContext);
 
    /**
     * Returns a matrix to map (x,y,z) world coordinates onto (u,v) LOS texture
     * coordinates, in the form expected by a matrix uniform.
     * This must only be called after InterpolateLOS.
     */
    const CMatrix3D& GetTextureMatrix();
 
    /**
     * Returns a matrix to map (0,0)-(1,1) texture coordinates onto LOS texture
     * coordinates, in the form expected by a matrix uniform.
     * This must only be called after InterpolateLOS.
     */
    const CMatrix3D& GetMinimapTextureMatrix();
 
private:
    void DeleteTexture();
    bool CreateShader();
    void ConstructTexture(Renderer::Backend::IDeviceCommandContext* deviceCommandContext);
    void RecomputeTexture(Renderer::Backend::IDeviceCommandContext* deviceCommandContext);
 
    size_t GetBitmapSize(size_t w, size_t h, size_t* pitch);
    void GenerateBitmap(const CLosQuerier& los, u8* losData, size_t w, size_t h, size_t pitch);
 
    CSimulation2& m_Simulation;
 
    bool m_Dirty = true;
 
    bool m_ShaderInitialized = false;
 
    // We need to choose the smallest format. We always use the red channel but
    // R8_UNORM might be unavailable on some platforms. So we fallback to
    // R8G8B8A8_UNORM.
    Renderer::Backend::Format m_TextureFormat =
        Renderer::Backend::Format::UNDEFINED;
    size_t m_TextureFormatStride = 0;
    std::unique_ptr<Renderer::Backend::ITexture>
        m_Texture, m_SmoothTextures[2];
    Renderer::Backend::IVertexInputLayout* m_VertexInputLayout = nullptr;
 
    uint32_t m_WhichTexture = 0;
    double m_LastTextureRecomputeTime = 0.0;
 
    // We update textures once a frame, so we change a Framebuffer once a frame.
    // That allows us to use two ping-pong FBOs instead of checking completeness
    // of Framebuffer each frame.
    std::unique_ptr<Renderer::Backend::IFramebuffer>
        m_SmoothFramebuffers[2];
    CShaderTechniquePtr m_SmoothTech;
 
    size_t m_MapSize = 0; // vertexes per side
 
    CMatrix3D m_TextureMatrix;
    CMatrix3D m_MinimapTextureMatrix;
};
 
#endif // INCLUDED_LOSTEXTURE