shader.h

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/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
 * Copyright (C) 2012-2020 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * Graphics Abstraction Layer (GAL) for OpenGL
 *
 * Shader class
 *
 * 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; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

#ifndef SHADER_H_
#define SHADER_H_

#include <gal/opengl/kiglew.h>    // Must be included first

#include <math/vector2d.h>

#include <string>
#include <deque>

namespace KIGFX
{
class OPENGL_GAL;

enum SHADER_TYPE
{
    SHADER_TYPE_VERTEX   = GL_VERTEX_SHADER,    
    SHADER_TYPE_FRAGMENT = GL_FRAGMENT_SHADER,  
    SHADER_TYPE_GEOMETRY = GL_GEOMETRY_SHADER   
};

namespace DETAIL {

inline const char* translateStringArg( const std::string& str )
{
    return str.c_str();
}

inline const char* translateStringArg( const char* str )
{
    return str;
}

}


class SHADER
{
public:

    SHADER();

    virtual ~SHADER();

    template< typename... Args >
    bool LoadShaderFromStrings( SHADER_TYPE aShaderType, Args&&... aArgs )
    {
        const char* arr[] = { DETAIL::translateStringArg( aArgs )... };
        return loadShaderFromStringArray( aShaderType, arr, sizeof...(Args) );
    }

    bool LoadShaderFromFile( SHADER_TYPE aShaderType, const std::string& aShaderSourceName );

    bool Link();

    bool IsLinked() const
    {
        return isShaderLinked;
    }

    inline void Use()
    {
        glUseProgram( programNumber );
        active = true;
    }

    inline void Deactivate()
    {
        glUseProgram( 0 );
        active = false;
    }

    inline bool IsActive() const
    {
        return active;
    }

    void ConfigureGeometryShader( GLuint maxVertices, GLuint geometryInputType,
                                  GLuint geometryOutputType );

    int AddParameter( const std::string& aParameterName );

    void SetParameter( int aParameterNumber, float aValue ) const;
    void SetParameter( int aParameterNumber, int aValue ) const;
    void SetParameter( int aParameterNumber, const VECTOR2D& aValue ) const;
    void SetParameter( int aParameterNumber, float f0, float f1, float f2, float f3 ) const;

    int GetAttribute( const std::string& aAttributeName ) const;

    static std::string ReadSource( const std::string& aShaderSourceName );

private:
    bool loadShaderFromStringArray( SHADER_TYPE aShaderType, const char** aArray, size_t aSize );

    void programInfo( GLuint aProgram );

    void shaderInfo( GLuint aShader );

    std::deque<GLuint>  shaderNumbers;      
    GLuint              programNumber;      
    bool                isProgramCreated;   
    bool                isShaderLinked;     
    bool                active;             
    GLuint              maximumVertices;    

    GLuint              geomInputType;

    GLuint              geomOutputType;
    std::deque<GLint>   parameterLocation;  
};
} // namespace KIGFX

#endif /* SHADER_H_ */