OpenGL simple mesh doesnt show - opengl

Question

for the last two days I've been watching following (really great and informative) tutorial series: http://www.youtube.com/playlist?list=PLEETnX-uPtBXT9T-hD0Bj31DSnwio-ywh
Last night I finished the part about meshes and now a red triangle is supposed to appear on my window, but it just doesn't. I don't know if it is a problem with my mesh or with my shader class (for both of them I don't get any errors). I use GLEW 1.10.0 for loading OpenGL, GLM 0.9.5.4 for OpenGL math stuff and SDL 2.0.3 for window stuff. Everything running on Windows 8.1 in Visual Studio 2013 Ultimate with the latest Nvidia graphics drivers.
Edit: I forgot to mention that the screen doesn't stay black, so the display.Clear method works. I hope thats any help.
Here are my shader and mesh files:
Shader.h:
#pragma once
#include <iostream>
#include <fstream>
#include <string>
#include <glew\glew.h>
using namespace std;
class Shader
{
public:
Shader(const string& fileName);
virtual ~Shader();
void Bind();
private:
string LoadShader(const string& fileName);
void CheckShaderError(GLuint shader, GLuint flag, bool isProgram, const string& errorMessage);
GLuint CreateShader(const string& text, GLenum shaderType);
static const unsigned int NUM_SHADERS = 2;
GLuint m_program;
GLuint m_shaders[NUM_SHADERS];
};
Shader.cpp
#include "Shader.h"
Shader::Shader(const string& fileName)
{
m_program = glCreateProgram();
m_shaders[0] = CreateShader(LoadShader(fileName + ".vert"), GL_VERTEX_SHADER);
m_shaders[1] = CreateShader(LoadShader(fileName + ".frag"), GL_FRAGMENT_SHADER);
for (unsigned int i = 0; i < NUM_SHADERS; i++)
glAttachShader(m_program, m_shaders[i]);
glLinkProgram(m_program);
CheckShaderError(m_program, GL_LINK_STATUS, true, "Error: Program linking failed");
glValidateProgram(m_program);
CheckShaderError(m_program, GL_VALIDATE_STATUS, true, "Error: Program is invalid");
}
Shader::~Shader()
{
for (unsigned int i = 0; i < NUM_SHADERS; i++)
{
glDetachShader(m_program, m_shaders[i]);
glDeleteShader(m_shaders[i]);
}
glDeleteProgram(m_program);
}
string Shader::LoadShader(const string& fileName)
{
ifstream file;
file.open(fileName.c_str());
string line;
string output;
if (file.is_open())
{
while (file.good())
{
getline(file, line);
output += (line + "\n");
}
}
else
{
cerr << "Unable to load shader: " << fileName << endl;
}
return output;
}
GLuint Shader::CreateShader(const string& text, GLenum shaderType)
{
GLuint shader = glCreateShader(shaderType);
if (shader == 0)
cerr << "Error: Shader creation failed!";
const GLchar* shaderSourceStrings[1] = { text.c_str() };
GLint shaderSourceStringLengths[1] = { text.length() };
glShaderSource(shader, 1, shaderSourceStrings, shaderSourceStringLengths);
glCompileShader(shader);
CheckShaderError(shader, GL_COMPILE_STATUS, false, "Error: Shader compilation failed");
return shader;
}
void Shader::Bind()
{
glUseProgram(m_program);
}
void Shader::CheckShaderError(GLuint shader, GLuint flag, bool isProgram, const string& errorMessage)
{
GLint success = 0;
GLchar error[1024] = { 0 };
if (isProgram)
glGetProgramiv(shader, flag, &success);
else
glGetShaderiv(shader, flag, &success);
if (success == GL_FALSE)
{
if (isProgram)
glGetProgramInfoLog(shader, sizeof(error), NULL, error);
else
glGetShaderInfoLog(shader, sizeof(error), NULL, error);
cerr << errorMessage << ": '" << error << "'" << endl;
}
}
BasicShader.vert:
#version 420 core
attribute vec3 position;
void main()
{
gl_Position = vec4(position, 1.0);
}
BasicShader.frag:
#version 420 core
void main()
{
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
Mesh.h:
#pragma once
#include <glew\glew.h>
#include "Vertex.h"
class Mesh
{
public:
Mesh(Vertex* vertecies, unsigned int numVertecies);
virtual ~Mesh();
void Draw();
private:
enum
{
POSITION_VB,
NUM_BUFFERS
};
GLuint m_vertexArrayObject;
GLuint m_vertexArrayBuffers[NUM_BUFFERS];
unsigned int m_drawCount;
};
Mesh.cpp:
#include "Mesh.h"
Mesh::Mesh(Vertex* vertecies, unsigned int numVertecies)
{
m_drawCount = numVertecies;
glGenVertexArrays(1, &m_vertexArrayObject);
glBindVertexArray(m_vertexArrayObject);
glGenBuffers(NUM_BUFFERS, m_vertexArrayBuffers);
glBindBuffer(GL_ARRAY_BUFFER, m_vertexArrayBuffers[POSITION_VB]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertecies[0]) * numVertecies, vertecies, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glBindVertexArray(0);
}
Mesh::~Mesh()
{
glDeleteBuffers(NUM_BUFFERS, m_vertexArrayBuffers);
glDeleteVertexArrays(1, &m_vertexArrayObject);
}
void Mesh::Draw()
{
glBindVertexArray(m_vertexArrayObject);
glDrawArrays(GL_TRIANGLES, 0, m_drawCount);
glBindVertexArray(0);
}
Vertex.h:
#pragma once
#include <glm\glm.hpp>
using namespace glm;
class Vertex
{
public:
Vertex(const vec3& pos);
virtual ~Vertex();
private:
vec3 m_pos;
};
Vertex.cpp:
#include "Vertex.h"
Vertex::Vertex(const vec3& pos)
{
m_pos = pos;
}
Vertex::~Vertex()
{
}
main.cpp:
#include "Display.h"
#include "Shader.h"
#include "Mesh.h"
using namespace std;
int main(int argc, char** argv)
{
Display display(800, 600, "Hello World");
Vertex vertecies[] =
{
Vertex(vec3(-0.5, -0.5, 0)),
Vertex(vec3(0, 0.5, 0)),
Vertex(vec3(0.5, -0.5, 0))
};
Mesh mesh(vertecies, sizeof(vertecies) / sizeof(vertecies[0]));
Shader shader(".\\res\\BasicShader");
while (!display.IsClosed())
{
display.Clear(0.0f, 0.15f, 0.3f, 1.0f);
shader.Bind();
mesh.Draw();
display.Update();
}
return 0;
}
I'd be very grateful for any help...

Answer 1

Try changing your vertex program to:
#version 420 core
layout(location = 0) in vec3 position;
void main()
{
gl_Position = vec4(position, 1.0);
}
and your fragment program to:
#version 420 core
out vec4 frag;
void main()
{
frag = vec4(1.0, 0.0, 0.0, 1.0);
}