const GLchar* vertexShaderSource = "#version 330 core\n"
"layout ( location = 0 ) in vec3 position;\n"
"void main( )\n"
"{\n"
"gl_Position = vec4( position.x, position.y, position.z, 1.0 );\n"
"}\n";
const GLchar* fragmentShaderSource = "#version 330 core\n"
"out vec4 color;\n"
"void main( )\n"
"{\n"
"color = vec4( 1.0f, 0.5f, 0.2f, 1.0f );\n"
"}\n";
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
GLenum err = glewInit();
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
GLint success;
GLchar infoLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "error (vertex)\n" << infoLog << std::endl;
}
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
std::cout << "error (fragment)\n" << infoLog << std::endl;
}
GLuint shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "error (program linking failed)\n" << infoLog << std::endl;
}
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
GLfloat vertices[] =
{
-0.5f, -0.5f, 0.0f, //bottem left
0.5f, -0.5f, 0.0f, //bottem right
0.0f, 0.5f, 0.0f
};
GLuint VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(shaderProgram);
glBindVertexArray(VAO);
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glfwTerminate();
return 0;
}
```
---
### Author:  [@dougbinks](https://discourse.glfw.org/u/dougbinks)
#### Post date: [May 12, 2020, 5:48pm UTC](https://discourse.glfw.org/t/exception-thrown-at-0x00000000-in-opengl/1559/2 "2020-05-12T17:48:16Z")
My guess would be that the function `glCreateShader` is `NULL`, i.e. GLEW was unable to load the extension. Have you checked that your driver supports this OpenGL feature (OpenGL 2.0 or the extension)?
---
### Author:  [@elmindreda](https://discourse.glfw.org/u/elmindreda)
#### Post date: [May 12, 2020, 5:57pm UTC](https://discourse.glfw.org/t/exception-thrown-at-0x00000000-in-opengl/1559/3 "2020-05-12T17:57:55Z")
You can ask GLFW to ensure the OpenGL context is version 3.3 (based on 330 in the shaders) or later by setting window hints between init and window creation:
```c
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
```
Then if version 3.3 is unavailable, `glfwCreateWindow` will fail.
---
### Author:  [@mmozeiko](https://discourse.glfw.org/u/mmozeiko)
#### Post date: [May 12, 2020, 7:16pm UTC](https://discourse.glfw.org/t/exception-thrown-at-0x00000000-in-opengl/1559/4 "2020-05-12T19:16:09Z")
The problem is that GLEW is initialized before OpenGL context is created and made current.
You should call `glewInit()` after `glfwMakeContextCurrent()` function.