View difference between Paste ID: k9CQnBjT and CrZRvxvb

 /*
  * GL01Hello.cpp: Test OpenGL C/C++ Setup
  */
 #include <windows.h>  // For MS Windows
 #include <GL/glut.h>  // GLUT, includes glu.h and gl.h'
 #include <iostream>
 
 /* Handler for window-repaint event. Call back when the window first appears and
    whenever the window needs to be re-painted. */
 void display() {
    int const win_width  = glutGet(GLUT_WINDOW_WIDTH);
-   glClear(GL_COLOR_BUFFER_BIT);         // Clear the color buffer
+   int const win_height = glutGet(GLUT_WINDOW_HEIGHT);
 
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set background color to black and opaque
    glClear(GL_COLOR_BUFFER_BIT);         // Clear the color buffer; this clears the whole window regardless of the set viewport
 
    glViewport(0, 0, win_width, win_height); // we can set the viewport after clearing
 
    // Draw a Red 1x1 Square centered at origin
    glBegin(GL_QUADS);              // Each set of 4 vertices form a quad
       glColor3f(1.0f, 0.0f, 0.0f); // Red
       glVertex2f(-0.5f, -0.5f);    // x, y
       glVertex2f( 0.5f, -0.5f);
       glVertex2f( 0.5f,  0.5f);
       glVertex2f(-0.5f,  0.5f);
    glEnd();
 
    glutSwapBuffers();
 }
 
 /* Main function: GLUT runs as a console application starting at main()  */
 int main(int argc, char** argv) {
 	std::cout<<"Hello, world!!"<<std::endl;
    glutInit(&argc, argv);                 // Initialize GLUT
 
    glutInitWindowSize(320, 320);   // Set the window's initial width & height
    glutInitWindowPosition(50, 50); // Position the window's initial top-left corner
    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
 
    glutCreateWindow("OpenGL Setup Test"); // Create a window with the given title
 
    glutDisplayFunc(display); // Register display callback handler for window re-paint
 
    glutMainLoop();           // Enter the infinitely event-processing loop
 
    return 0;
 }