LOSTexture.h

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/* Copyright (C) 2014 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/>.
 */

#include "lib/ogl.h"

#include "maths/Matrix3D.h"
#include "simulation2/components/ICmpRangeManager.h"

#include "graphics/ShaderManager.h"


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 binds it to the requested
     * texture unit.
     * Also switches the current active texture unit, and enables texturing on it.
     * The texture is in 8-bit ALPHA format.
     */
    void BindTexture(int unit);

    /**
     * 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.
     */
    GLuint GetTexture();

    void InterpolateLOS();
    GLuint GetTextureSmooth();

    /**
     * Returns a matrix to map (x,y,z) world coordinates onto (u,v) LOS texture
     * coordinates, in the form expected by glLoadMatrixf.
     * This must only be called after BindTexture.
     */
    const CMatrix3D& GetTextureMatrix();

    /**
     * Returns a matrix to map (0,0)-(1,1) texture coordinates onto LOS texture
     * coordinates, in the form expected by glLoadMatrixf.
     * This must only be called after BindTexture.
     */
    const CMatrix3D* GetMinimapTextureMatrix();

private:
    void DeleteTexture();
    bool CreateShader();
    void ConstructTexture(int unit);
    void RecomputeTexture(int unit);

    size_t GetBitmapSize(size_t w, size_t h, size_t* pitch);
    void GenerateBitmap(ICmpRangeManager::CLosQuerier los, u8* losData, size_t w, size_t h, size_t pitch);

    CSimulation2& m_Simulation;

    bool m_Dirty;

    bool m_ShaderInitialized;

    GLuint m_Texture;
    GLuint m_TextureSmooth1, m_TextureSmooth2;

    bool whichTex;

    GLuint m_smoothFbo;
    CShaderTechniquePtr m_smoothShader;

    ssize_t m_MapSize; // vertexes per side
    GLsizei m_TextureSize; // texels per side

    CMatrix3D m_TextureMatrix;
    CMatrix3D m_MinimapTextureMatrix;
};