PostprocManager.h

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/* Copyright (C) 2012 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_POSTPROCMANAGER
#define INCLUDED_POSTPROCMANAGER


#include "graphics/ShaderTechnique.h"

class CPostprocManager
{
private:
    
    // Two framebuffers, that we flip between at each shader pass.
    GLuint m_PingFbo, m_PongFbo;
    
    // Unique colour textures for the framebuffers.
    GLuint m_ColourTex1, m_ColourTex2;
    
    // The framebuffers share a depth/stencil texture.
    GLuint m_DepthTex;
    
    // A framebuffer and textures x2 for each blur level we render. 
    GLuint m_BloomFbo, m_BlurTex2a, m_BlurTex2b, m_BlurTex4a, m_BlurTex4b, m_BlurTex8a, m_BlurTex8b;
    
    // Indicates which of the ping-pong buffers is used for reading and which for drawing.
    bool m_WhichBuffer;
    
    // The name and shader technique we are using. "default" name means no technique is used
    // (i.e. while we do allocate the buffers, no effects are rendered).
    CStrW m_PostProcEffect;
    CShaderTechniquePtr m_PostProcTech;
    
    // The current screen dimensions in pixels.
    int m_Width, m_Height;
    
    // Is the postproc manager initialised? Buffers created? Default effect loaded?
    bool m_IsInitialised;
    
    // Creates blur textures at various scales, for bloom, DOF, etc.
    void ApplyBlur();
    
    // High quality GPU image scaling to half size. outTex must have exactly half the size
    // of inTex. inWidth and inHeight are the dimensions of inTex in texels.
    void ApplyBlurDownscale2x(GLuint inTex, GLuint outTex, int inWidth, int inHeight);
    
    // GPU-based Gaussian blur in two passes. inOutTex contains the input image and will be filled 
    // with the blurred image. tempTex must have the same size as inOutTex. 
    // inWidth and inHeight are the dimensions of the images in texels.
    void ApplyBlurGauss(GLuint inOutTex, GLuint tempTex, int inWidth, int inHeight);
    
    // Applies a pass of a given effect to the entire current framebuffer. The shader is 
    // provided with a number of general-purpose variables, including the rendered screen so far,
    // the depth buffer, a number of blur textures, the screen size, the zNear/zFar planes and
    // some other parameters used by the optional bloom/HDR pass.
    void ApplyEffect(CShaderTechniquePtr &shaderTech1, int pass);
    
public:
    CPostprocManager();
    ~CPostprocManager();
    
    // Create all buffers/textures in GPU memory and set default effect.
    void Initialize();
    
    // Delete all allocated buffers/textures from GPU memory.
    void Cleanup();
    
    // Delete existing buffers/textures and create them again, using a new screen size if needed.
    // (the textures are also attached to the framebuffers)
    void RecreateBuffers();
    
    // Loads a new postproc effect. "default" effect does NOT load anything.
    void LoadEffect(CStrW &name);
    
    // Returns a list of xml files found in shaders/effects/postproc.
    std::vector<CStrW> GetPostEffects() const;
    
    // Returns the name of the current effect.
    inline const CStrW& GetPostEffect() const 
    {
        return m_PostProcEffect;
    }
    
    // Matching setter that calls LoadEffect.
    void SetPostEffect(CStrW name);

    // Clears the two colour buffers and depth buffer, and redirects all rendering
    // to our textures instead of directly to the system framebuffer. 
    void CaptureRenderOutput();
    
    // First renders blur textures, then calls ApplyEffect for each effect pass, 
    // ping-ponging the buffers at each step.
    void ApplyPostproc();
    
    // Blits the final postprocessed texture to the system framebuffer. The system framebuffer
    // is selected as the output buffer. Should be called before silhouette rendering.
    void ReleaseRenderOutput();
};


#endif //INCLUDED_POSTPROCMANAGER