pi_shaders.h

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/***************************************************************************
 *   Copyright (C) 2017 by David S. Register                               *
 *                                                                         *
 *   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/>. *
 **************************************************************************/
 
#ifndef PISHADERS_H__
#define PISHADERS_H__
 
#include <wx/wxprec.h>
 
#ifndef WX_PRECOMP
#include <wx/wx.h>
#endif
 
#include "pi_gl.h"
 
extern GLint GRIBpi_color_tri_shader_program;
extern GLint GRIBpi_colorv_tri_shader_program;
extern GLint pi_texture_2D_shader_program;
extern GLint pi_circle_filled_shader_program;
 
bool pi_loadShaders();
void configureShaders(float width, float height);
 
extern const GLchar *PI_shader_preamble;
 
enum Consts { INFOLOG_LEN = 512 };
 
class PI_GLShaderProgram {
public:
  class Builder {
  public:
    Builder() : linked_(false) { programId_ = glCreateProgram(); }
 
    Builder &addShaderFromSource(std::string const &shaderSource,
                                 GLenum shaderType) {
      char const *shaderCStr = shaderSource.c_str();
      GLuint shaderId = glCreateShader(shaderType);
 
      GLchar const *files[] = {PI_shader_preamble, shaderCStr};
      GLint lengths[] = {(GLint)strlen(PI_shader_preamble),
                         (GLint)strlen(shaderCStr)};
 
      glShaderSource(shaderId, 2, files, lengths);
      // glShaderSource(shaderId, 1, &shaderCStr, nullptr);
 
      glCompileShader(shaderId);
      glGetShaderiv(shaderId, GL_COMPILE_STATUS, &success);
      if (!success) {
        glGetShaderInfoLog(shaderId, INFOLOG_LEN, nullptr, infoLog);
        printf("ERROR::SHADER::COMPILATION_FAILED\n%s\n", infoLog);
        // ret_val = false;
      }
 
      glAttachShader(programId_, shaderId);
      return *this;
    }
 
    //         void addShaderFromFile(std::string const &shaderFile, GLenum
    //         shaderType) {
    //             std::ifstream fileName(shaderFile);
    //             std::istreambuf_iterator<char> fileBegin(fileName), fileEnd;
    //             std::string fileContents(fileBegin, fileEnd);
    //             return addShaderFromSource(fileContents, shaderType);
    //         }
 
    PI_GLShaderProgram linkProgram() {
      glLinkProgram(programId_);
      glGetProgramiv(programId_, GL_LINK_STATUS,
                     &linkSuccess);  // requesting the status
      if (linkSuccess == GL_FALSE) {
        glGetProgramInfoLog(programId_, INFOLOG_LEN, nullptr, infoLog);
        printf("ERROR::SHADER::LINK_FAILED\n%s\n", infoLog);
      }
 
      PI_GLShaderProgram theProgram(programId_);
      // deleteAttachedShaders(programId_);
      linked_ = true;
      return theProgram;
    }
 
    ~Builder() {
      if (!linked_) {
        glDeleteProgram(programId_);
      }
    }
 
  private:
    GLuint programId_;
    bool linked_;
    GLint success;
    GLint linkSuccess;
    GLchar infoLog[INFOLOG_LEN];
  };
 
  PI_GLShaderProgram() : programId_(0) {}
 
  PI_GLShaderProgram(PI_GLShaderProgram &&other) { *this = std::move(other); }
 
  PI_GLShaderProgram &operator=(PI_GLShaderProgram &&other) {
    programId_ = other.programId_;
    other.programId_ = 0;
 
    if (other.programId_ != 0) {
      glDeleteProgram(other.programId_);
    }
 
    return *this;
  }
 
  ~PI_GLShaderProgram() = default;
 
  GLuint programId() const { return programId_; }
 
  PI_GLShaderProgram(PI_GLShaderProgram const &other) = delete;
  PI_GLShaderProgram &operator=(PI_GLShaderProgram const &other) = delete;
 
private:
  PI_GLShaderProgram(GLuint programId) : programId_(programId) {}
  GLuint programId_;
};
 
#endif  //      PISHADERS_H__