glCreateShader fails and return 0 - c++

Question

I'm having a problem with glCreateShaders. It always returns 0. I'm using Glew with SDL and whenever I run the program, it says:
0(1) : error C0000: syntax error, unexpected '}' at token "}"
Shader Shaders/colorShading.vert failed to compile!
main.cpp:
#include <iostream>
#include "MainGame.h"
int main(int argc, char** argv)
{
MainGame maingame;
maingame.run();
return 0;
}
MainGame.h:
//Core -> initializing glew, sdl etc...
//Just ignore the sprite class
#pragma once
#include <SDL/SDL.h>
#include <GL/glew.h>
#include <iostream>
#include <string>
#include "Errors.h"
#include "GLSLProgram.h"
enum class GameState {PLAY, EXIT};
#include "Sprite.h"
class MainGame
{
public:
MainGame(void);
~MainGame(void);
void run();
private:
void initSystems();
void initShaders();
void gameLoop();
void processInput();
void drawGame();
SDL_Window* _window;
int _screenWidth;
int _screenHeight;
GameState _gameState;
Sprite _sprite;
GLSLProgram _colorProgram;
};
MainGame.cpp:
#include "MainGame.h"
MainGame::MainGame(void)
{
_window = nullptr;
_screenWidth = 1024;
_screenHeight = 700;
_gameState = GameState::PLAY;
}
MainGame::~MainGame(void)
{
}
void MainGame::run()
{
initSystems();
_sprite.init(-1.0f, -1.0f, 1.0f, 1.0f);
gameLoop();
}
void MainGame::initSystems()
{
//Initialize SDL
SDL_Init(SDL_INIT_EVERYTHING);
_window = SDL_CreateWindow("Game Engine", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, _screenWidth, _screenHeight, SDL_WINDOW_OPENGL);
if (_window == nullptr)
{
fatalError("SDL Window could not be created!");
}
SDL_GLContext glContext = SDL_GL_CreateContext(_window);
if (glContext == nullptr)
fatalError("SDL_GL context could not be created!");
GLenum error = glewInit();
if (error != GLEW_OK)
fatalError("Could not initialize glew!");
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
initShaders();
}
void MainGame::initShaders()
{
_colorProgram.compileShaders("Shaders/colorShading.vert", "Shaders/colorShading.frag");
_colorProgram.addAttribute("vertexPosition");
_colorProgram.linkShaders();
}
void MainGame::gameLoop()
{
while (_gameState != GameState::EXIT)
{
processInput();
drawGame();
}
}
void MainGame::processInput()
{
SDL_Event evnt;
while (SDL_PollEvent(&evnt))
{
switch (evnt.type)
{
case SDL_QUIT:
_gameState = GameState::EXIT;
break;
case SDL_MOUSEMOTION:
std::cout << "New Coords: " << evnt.motion.x << " " << evnt.motion.y << std::endl;
break;
}
}
}
void MainGame::drawGame()
{
glClearDepth(1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
_colorProgram.use();
_sprite.draw();
_colorProgram.unUse();
SDL_GL_SwapWindow(_window);
}
GLSLProgram.h:
//Used for
#pragma once
#include <string>
#include <GL/glew.h>
//#include <SDL/SDL.h>
#include "Errors.h"
class GLSLProgram
{
public:
GLSLProgram();
~GLSLProgram();
void compileShaders(const std::string& vertextShaderFilePath, const std::string& fragmentShaderFilePath);
void linkShaders();
void addAttribute(const std::string&);
void use();
void unUse();
private:
int _numAttributes;
void _compileShader(const std::string&, GLuint);
GLuint _programID;
GLuint _vertexShaderID;
GLuint _fragmentShaderID;
};
GLSLProgram.cpp:
//Used for compiling shaders
#include "GLSLProgram.h"
#include <fstream>
#include <vector>
GLSLProgram::GLSLProgram() : _numAttributes(0), _programID(0), _vertexShaderID(0), _fragmentShaderID(0)
{
}
GLSLProgram::~GLSLProgram()
{
}
void GLSLProgram::compileShaders(const std::string& vertexShaderFilePath, const std::string& fragmentShaderFilePath)
{
_vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
if (_vertexShaderID == 0)
{
fatalError("Vertex shader failed to be created!");
SDL_Quit();
}
_fragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
if (_fragmentShaderID == 0)
{
fatalError("Fragment shader failed to be created!");
SDL_Quit();
}
_compileShader(vertexShaderFilePath, _vertexShaderID);
_compileShader(fragmentShaderFilePath, _fragmentShaderID);
}
void GLSLProgram::addAttribute(const std::string& attributeName)
{
glBindAttribLocation(_programID, _numAttributes++, attributeName.c_str());
}
void GLSLProgram::use()
{
glUseProgram(_programID);
for (int x = 0; x < _numAttributes; x++)
{
glEnableVertexAttribArray(x);
}
}
void GLSLProgram::unUse()
{
glUseProgram(0);
for (int x = 0; x < _numAttributes; x++)
{
glDisableVertexAttribArray(x);
}
}
void GLSLProgram::linkShaders()
{
//Vertex and fragment shaders are successfully compiled.
//Now time to link them together into a program.
//Get a program object.
_programID = glCreateProgram();
//Attach our shaders to our program
glAttachShader(_programID, _vertexShaderID);
glAttachShader(_programID, _fragmentShaderID);
//Link our program
glLinkProgram(_programID);
//Note the different functions here: glGetProgram* instead of glGetShader*.
GLint isLinked = 0;
glGetProgramiv(_programID, GL_LINK_STATUS, (int *)&isLinked);
if (isLinked == GL_FALSE)
{
GLint maxLength = 0;
glGetProgramiv(_programID, GL_INFO_LOG_LENGTH, &maxLength);
//The maxLength includes the NULL character
std::vector<char> infoLog(maxLength);
glGetProgramInfoLog(_programID, maxLength, &maxLength, &infoLog[0]);
//We don't need the program anymore.
glDeleteProgram(_programID);
//Don't leak shaders either.
glDeleteShader(_vertexShaderID);
glDeleteShader(_fragmentShaderID);
printf("%s\n", &(infoLog[0]));
fatalError("Shaders failed to link!");
}
//Always detach shaders after a successful link.
glDetachShader(_programID, _vertexShaderID);
glDetachShader(_programID, _fragmentShaderID);
glDeleteProgram(_programID);
glDeleteShader(_vertexShaderID);
glDeleteShader(_fragmentShaderID);
}
void GLSLProgram::_compileShader(const std::string &filePath, GLuint id)
{
std::ifstream vertexFile(filePath);
if (vertexFile.fail())
{
perror(filePath.c_str());
fatalError("Failed to open " + filePath);
}
std::string fileContents;
std::string line;
while (std::getline(vertexFile, line));
{
fileContents += line + "\n";
}
vertexFile.close();
const char *contentsPtr = fileContents.c_str();
glShaderSource(id, 1, &contentsPtr, nullptr);
glCompileShader(id);
GLint isCompiled = 0;
glGetShaderiv(id, GL_COMPILE_STATUS, &isCompiled);
if (isCompiled == GL_FALSE)
{
GLint maxLength = 0;
glGetShaderiv(id, GL_INFO_LOG_LENGTH, &maxLength);
//The maxLength includes the NULL character
std::vector<char> errorLog(maxLength);
glGetShaderInfoLog(id, maxLength, &maxLength, &errorLog[0]);
//Provide the infolog in whatever manor you deem best.
//Exit with failure.
glDeleteShader(id); //Don't leak the shader.
printf("%s\n", &(errorLog[0]));
fatalError("Shader" + filePath + "failed to compile!");
}
}
vertex shader:
#version 130
//The vertex shader operates on each vertex
//input data from the VBO. Each vertex is 2 floats
in vec2 vertexPosition;
void main()
{
//Set the x,y position on the screen
gl_Position.xy = vertexPosition;
//the z position is zero since we are in 2D
gl_Position.z = 0.0;
//Indicate that the coordinates are normalized
gl_Position.w = 1.0;
}
and fragment shader:
#version 130
//The fragment shader operates on each pixel in a given polygon
//This is the 3 component float vector that gets outputted to the screen
//for each pixel.
out vec3 color;
void main() {
//Just hardcode the color to red
color = vec3(1.0, 0.0, 1.0);
}
I don't have any idea why it is happening. :(
PS: I'm beginner with glew so please don't answer with some advance stuff:D
Edit 1:
02/11/2014 (11/02/2014 for Americans)
I downloaded the source code from the tutorial I was using and it is working. So there's something with my code. I will edit the post when I find the problem.

Answer 1

Remove semicolon in file GLSLProgram.cpp at line:
while (std::getline(vertexFile, line));
You go through the file and then just add to the empty string fileContents the last line of your shader code, that is '}'.