RGB gradient

Adding a for loop to the last piece of code, I made a series of gradients:

The code hasn't been edited much. Just added one for loop to draw scan lines of the same color (that gives another idea). However, the coordinates are set to 200 x 150 where as the window size is set to 400 x 300. This makes the code to draw like this:














This is not correct. If you click on the image, it will show it full size, where every other line is left totally blank. So, I edited the window size to be 200 x 150 too. Although, I could have changed the coordinates range too.
Another note, for this wrong example, I edited the background to white, like the previous code, instead of keeping it black in the correct versions.

Here's the code:

#include <GL/glut.h>

void init (void) {
    glClearColor (1.0, 1.0 ,1.0, 0.0);

    glMatrixMode (GL_PROJECTION);
    gluOrtho2D (0., 200.0, 0.0, 150.0);    // the coordinate range
}

void lineSegment (void) {

    int count;
    float col = 0.0;

    glClear (GL_COLOR_BUFFER_BIT);
    glBegin (GL_LINES);
        for (count = 0; count < 201; count += 1){
            glColor3f (col, 0.0, 0.0);
            glVertex2i (1, count);
            glVertex2i (200, count);
            col = col + 0.005;
        }
    glEnd();

    glFlush();
}

void main (int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowPosition (50, 100);    // top-left window position
    glutInitWindowSize(200, 150);    // window size
    glutCreateWindow ("Red");

    init();
    glutDisplayFunc (lineSegment);
    glutMainLoop ();
}