Opengl not working example

main.cpp

#include <SDL.h>
#include "glad.c"

int main(int argc,char **argv){
    
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_DisplayMode CurrentDisplay;
    SDL_GetCurrentDisplayMode(0, &CurrentDisplay);  
    SDL_Window *Window = SDL_CreateWindow("Game SDL",10,10,800,600,SDL_WINDOW_OPENGL|SDL_WINDOW_SHOWN);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
    SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
    SDL_GL_SetSwapInterval(-1);
    SDL_GLContext glcontext = SDL_GL_CreateContext(Window);
    SDL_GL_LoadLibrary(NULL);
    gladLoadGLLoader(SDL_GL_GetProcAddress);
    printf("Vendor:   %s\n", glGetString(GL_VENDOR));
    printf("Renderer: %s\n", glGetString(GL_RENDERER));
    printf("Version:  %s\n", glGetString(GL_VERSION));
    SDL_Event event;
    GLuint VertexArrayID;
    glGenVertexArrays(1, &VertexArrayID);
    glBindVertexArray(VertexArrayID);
    static GLfloat VAO_data[] = {
        -1.0f, -1.0f, 0.0f,
        1.0f, -1.0f, 0.0f,
        0.0f,  1.0f, 0.0f,
    };
    // This will identify our vertex buffer
    GLuint vertexbuffer;
// Generate 1 buffer, put the resulting identifier in vertexbuffer
    glGenBuffers(1, &vertexbuffer);
// The following commands will talk about our 'vertexbuffer' buffer
    glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
// Give our vertices to OpenGL.
    glBufferData(GL_ARRAY_BUFFER, sizeof(VAO_data), VAO_data, GL_STATIC_DRAW);
    bool running = true;
    while(running){
        while(SDL_PollEvent(&event)){
            //handle event
            if(event.type == SDL_QUIT) running = false;
        }    
        glClear(GL_COLOR_BUFFER_BIT);
        glClearColor(1,1,0,1);
        glClear (GL_COLOR_BUFFER_BIT); // Clear the window
        glLoadIdentity ();
        glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
        glVertexAttribPointer(
            0,                  // attribute 0. No particular reason for 0, but must match the layout in the shader.
            3,                  // size
            GL_FLOAT,           // type
            GL_FALSE,           // normalized?
            0,                  // stride
            (void*)0            // array buffer offset
                              );
// Draw the triangle !
        glDrawArrays(GL_TRIANGLES, 0, 3); // Starting from vertex 0; 3 vertices total -> 1 triangle
        glDisableVertexAttribArray(0);
        // Create the shaders
        GLint Result = GL_FALSE;
    int InfoLogLength;
    char * VertexSource = "#version 120
layout(location = 0) in vec3 vertexPosition_modelspace;
void main(){
gl_Position.xyz = vertexPosition_modelspace;
  gl_Position.w = 1.0;
}
";
    char * FragmentSource = "#version 120
out vec3 color;
void main(){
  color = vec3(1,0,0);
}";
    GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
    GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
    //Compile Shaders
glShaderSource(VertexShaderID, 1, &VertexSource , NULL);
    glCompileShader(VertexShaderID);
    // Check Vertex Shader
    glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
    glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
    // Compile Fragment Shader
    glShaderSource(FragmentShaderID, 1, &FragmentSource , NULL);
    glCompileShader(FragmentShaderID);

    // Check Fragment Shader
    glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
    glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);

    // Link the program
    printf("Linking program\n");
    GLuint ProgramID = glCreateProgram();
    glAttachShader(ProgramID, VertexShaderID);
    glAttachShader(ProgramID, FragmentShaderID);
    glLinkProgram(ProgramID);

    glDetachShader(ProgramID, VertexShaderID);
    glDetachShader(ProgramID, FragmentShaderID);
    
    glDeleteShader(VertexShaderID);
    glDeleteShader(FragmentShaderID);
    SDL_GL_SwapWindow(Window);
    }
    return 0;
}