/*
 *   Copyright © 2010 Fredrik Höglund <fredrik@kde.org>
 *
 *   This program 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.
 *
 *   This program 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 this program; see the file COPYING.  if not, write to
 *   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *   Boston, MA 02110-1301, USA.
 */

#ifndef BLURSHADER_H
#define BLURSHADER_H

#include <kwinglutils.h>

namespace KWin
{

class BlurShader
{
public:
    BlurShader();
    virtual ~BlurShader();

    static BlurShader *create();

    // Sets the radius in pixels
    void setRadius(int radius);
    int radius() const { return mRadius; }

    // Sets the blur direction
    void setDirection(Qt::Orientation direction);
    Qt::Orientation direction() const { return mDirection; }

    // Sets the distance between two pixels
    virtual void setPixelDistance(float val) = 0;

    // The opacity of the resulting pixels is multiplied by this value
    virtual void setOpacity(float val) = 0;

    virtual void bind() = 0;
    virtual void unbind() = 0;

protected:
    float gaussian(float x, float sigma) const;
    QVector<float> gaussianKernel() const;
    virtual void init() = 0;
    virtual void reset() = 0;
    virtual int maxKernelSize() const = 0;

private:
    int mRadius;
    Qt::Orientation mDirection;
};


// ----------------------------------------------------------------------------



class GLSLBlurShader : public BlurShader
{
public:
    GLSLBlurShader();
    ~GLSLBlurShader();

    void setPixelDistance(float val);
    void setOpacity(float val);
    void bind();
    void unbind();

protected:
    void init();
    void reset();
    int maxKernelSize() const;

    GLuint compile(GLenum type, const QByteArray &source);
    GLuint link(GLuint vertexShader, GLuint fragmentShader);

private:
    GLuint program;
    int uTexUnit;
    int uPixelSize;
    int uOpacity;
};



// ----------------------------------------------------------------------------



class ARBBlurShader : public BlurShader
{
public:
    ARBBlurShader();
    ~ARBBlurShader();

    void setPixelDistance(float val);
    void setOpacity(float val);
    void bind();
    void unbind();

protected:
    void init();
    void reset();
    int maxKernelSize() const;

private:
    GLuint program;
};

} // namespace KWin

#endif