shader.cpp

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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 The 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, see <https://www.gnu.org/licenses/>.
 */
 
#include <iostream>
#include <fstream>
#include <stdexcept>
 
#include <cstring>
#include <cassert>
 
#include <gal/opengl/shader.h>
#include <vector>
 
using namespace KIGFX;
 
SHADER::SHADER() :
        isProgramCreated( false ),
        isShaderLinked( false ),
        active( false ),
        maximumVertices( 4 ),
        geomInputType( GL_LINES ),
        geomOutputType( GL_LINES )
 
{
    // Do not have uninitialized members:
    programNumber = 0;
}
 
 
SHADER::~SHADER()
{
    if( active )
        Deactivate();
 
    if( isProgramCreated )
    {
        if( glIsShader )
        {
            // Delete the shaders and the program
            for( std::deque<GLuint>::iterator it = shaderNumbers.begin(); it != shaderNumbers.end();
                 ++it )
            {
                GLuint shader = *it;
 
                if( glIsShader( shader ) )
                {
                    glDetachShader( programNumber, shader );
                    glDeleteShader( shader );
                }
            }
 
            glDeleteProgram( programNumber );
        }
    }
}
 
 
bool SHADER::LoadShaderFromFile( SHADER_TYPE aShaderType, const std::string& aShaderSourceName )
{
    // Load shader sources
    const std::string shaderSource = ReadSource( aShaderSourceName );
 
    return LoadShaderFromStrings( aShaderType, shaderSource );
}
 
 
void SHADER::ConfigureGeometryShader( GLuint maxVertices, GLuint geometryInputType,
                                      GLuint geometryOutputType )
{
    maximumVertices = maxVertices;
    geomInputType = geometryInputType;
    geomOutputType = geometryOutputType;
}
 
 
bool SHADER::Link()
{
    // Shader linking
    glLinkProgram( programNumber );
    programInfo( programNumber );
 
    // Check the Link state
    GLint tmp;
    glGetProgramiv( programNumber, GL_LINK_STATUS, &tmp );
    isShaderLinked = !!tmp;
 
#ifdef DEBUG
    if( !isShaderLinked )
    {
        int maxLength;
        glGetProgramiv( programNumber, GL_INFO_LOG_LENGTH, &maxLength );
        maxLength = maxLength + 1;
        char* linkInfoLog = new char[maxLength];
        glGetProgramInfoLog( programNumber, maxLength, &maxLength, linkInfoLog );
        std::cerr << "Shader linking error:" << std::endl;
        std::cerr << linkInfoLog;
        delete[] linkInfoLog;
    }
#endif /* DEBUG */
 
    return isShaderLinked;
}
 
 
int SHADER::AddParameter( const std::string& aParameterName )
{
    GLint location = glGetUniformLocation( programNumber, aParameterName.c_str() );
 
    if( location >= 0 )
        parameterLocation.push_back( location );
    else
        throw std::runtime_error( "Could not find shader uniform: " + aParameterName );
 
    return static_cast<int>( parameterLocation.size() ) - 1;
}
 
 
void SHADER::SetParameter( int parameterNumber, float value ) const
{
    assert( (unsigned) parameterNumber < parameterLocation.size() );
 
    glUniform1f( parameterLocation[parameterNumber], value );
}
 
 
void SHADER::SetParameter( int parameterNumber, int value ) const
{
    assert( (unsigned) parameterNumber < parameterLocation.size() );
 
    glUniform1i( parameterLocation[parameterNumber], value );
}
 
 
void SHADER::SetParameter( int parameterNumber, float f0, float f1, float f2, float f3 ) const
{
    assert( (unsigned) parameterNumber < parameterLocation.size() );
    float arr[4] = { f0, f1, f2, f3 };
    glUniform4fv( parameterLocation[parameterNumber], 1, arr );
}
 
 
void SHADER::SetParameter( int aParameterNumber, const VECTOR2D& aValue ) const
{
    assert( (unsigned) aParameterNumber < parameterLocation.size() );
    glUniform2f( parameterLocation[aParameterNumber], static_cast<GLfloat>( aValue.x ),
                 static_cast<GLfloat>( aValue.y ) );
}
 
 
int SHADER::GetAttribute( const std::string& aAttributeName ) const
{
    return glGetAttribLocation( programNumber, aAttributeName.c_str() );
}
 
 
void SHADER::programInfo( GLuint aProgram )
{
    GLint glInfoLogLength = 0;
    GLint writtenChars = 0;
 
    // Get the length of the info string
    glGetProgramiv( aProgram, GL_INFO_LOG_LENGTH, &glInfoLogLength );
 
    // Print the information
    if( glInfoLogLength > 2 )
    {
        GLchar* glInfoLog = new GLchar[glInfoLogLength];
        glGetProgramInfoLog( aProgram, glInfoLogLength, &writtenChars, glInfoLog );
 
        delete[] glInfoLog;
    }
}
 
 
void SHADER::shaderInfo( GLuint aShader )
{
    GLint glInfoLogLength = 0;
    GLint writtenChars = 0;
 
    // Get the length of the info string
    glGetShaderiv( aShader, GL_INFO_LOG_LENGTH, &glInfoLogLength );
 
    // Print the information
    if( glInfoLogLength > 2 )
    {
        GLchar* glInfoLog = new GLchar[glInfoLogLength];
        glGetShaderInfoLog( aShader, glInfoLogLength, &writtenChars, glInfoLog );
 
        delete[] glInfoLog;
    }
}
 
 
std::string SHADER::ReadSource( const std::string& aShaderSourceName )
{
    // Open the shader source for reading
    std::ifstream inputFile( aShaderSourceName.c_str(), std::ifstream::in );
    std::string   shaderSource;
 
    if( !inputFile )
        throw std::runtime_error( "Can't read the shader source: " + aShaderSourceName );
 
    std::string shaderSourceLine;
 
    // Read all lines from the text file
    while( getline( inputFile, shaderSourceLine ) )
    {
        shaderSource += shaderSourceLine;
        shaderSource += "\n";
    }
 
    return shaderSource;
}
 
 
bool SHADER::loadShaderFromStringArray( SHADER_TYPE aShaderType, const char** aArray, size_t aSize )
{
    assert( !isShaderLinked );
 
    // Create the program
    if( !isProgramCreated )
    {
        programNumber = glCreateProgram();
        isProgramCreated = true;
    }
 
    // Create a shader
    GLuint shaderNumber = glCreateShader( aShaderType );
    shaderNumbers.push_back( shaderNumber );
 
    // Get the program info
    programInfo( programNumber );
 
    // Attach the sources
    glShaderSource( shaderNumber, static_cast<GLsizei>( aSize ), (const GLchar**) aArray, nullptr );
    programInfo( programNumber );
 
    // Compile and attach shader to the program
    glCompileShader( shaderNumber );
    GLint status;
    glGetShaderiv( shaderNumber, GL_COMPILE_STATUS, &status );
 
    if( status != GL_TRUE )
    {
        shaderInfo( shaderNumber );
 
        GLint maxLength = 0;
        glGetShaderiv( shaderNumber, GL_INFO_LOG_LENGTH, &maxLength );
 
        // The maxLength includes the NULL character
        std::vector<GLchar> errorLog( (size_t) maxLength );
        glGetShaderInfoLog( shaderNumber, maxLength, &maxLength, &errorLog[0] );
 
        // Provide the infolog in whatever manor you deem best.
        // Exit with failure.
        glDeleteShader( shaderNumber ); // Don't leak the shader.
 
        throw std::runtime_error( &errorLog[0] );
    }
 
    glAttachShader( programNumber, shaderNumber );
    programInfo( programNumber );
 
    // Special handling for the geometry shader
    if( aShaderType == SHADER_TYPE_GEOMETRY )
    {
        if( GLAD_GL_ARB_geometry_shader4 || GLAD_GL_EXT_geometry_shader4 )
        {
            glProgramParameteri( programNumber, GL_GEOMETRY_VERTICES_OUT_EXT, maximumVertices );
            glProgramParameteri( programNumber, GL_GEOMETRY_INPUT_TYPE_EXT, geomInputType );
            glProgramParameteri( programNumber, GL_GEOMETRY_OUTPUT_TYPE_EXT, geomOutputType );
        }
    }
    return true;
}