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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 ();
}

First OpenGL program

Today I created my first ever OpenGL program. I had this book for ages but haven't been able to understand even the basics. But, today (night, actually), thanks to Allah, I have been able to make a program. And it does an amazing thing, which no other program has ever done before. Thats right. It prints my nick on the screen. :D

Screenshot:

Here is the source code:

#include <GL\glut.h>

void init (void) {
    glClearColor (1.0, 1.0 ,1.0, 0.0);  // set display window color to white

    glMatrixMode (GL_PROJECTION);       // set projection parameters
    gluOrtho2D (0., 200.0, 0.0, 150.0);
}

void draw1Line (int x1, int y1, int x2, int y2) {
    glBegin (GL_LINES);
        glVertex2i (x1, y1);
        glVertex2i (x2, y2);
    glEnd();
}

void lineSegment (void) {
    glClear (GL_COLOR_BUFFER_BIT);      // clear display window

    glColor3f (1.0, 0.0, 0.0);          // set line segment color to red
    
    // specify line segment geometry
    draw1Line (10,90,35,90);
    draw1Line (10,90,10,65);
    draw1Line (10,65,35,65);
    draw1Line (35,65,35,40);
    draw1Line (10,40,35,40);
    draw1Line (45,40,45,90);
    draw1Line (45,90,69,90);
    draw1Line (69,90,69,65);
    draw1Line (69,65,45,65);
    draw1Line (45,65,70,40);
    draw1Line (80,40,80,90);
    draw1Line (80,90,92,65);
    draw1Line (92,65,104,90);
    draw1Line (104,90,104,40);

    glFlush();           // Process all OpenGL routines as quickly as possible
}

void main (int argc, char** argv) {
    glutInit(&argc, argv);          // initialize glut
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);    // set display mode
    glutInitWindowPosition (50, 100);   // set top-left display window position
    glutInitWindowSize(400, 300);       // set display window size
    glutCreateWindow ("SRMROX!");       // create display windows

    init();                             // initialize procedure
    glutDisplayFunc (lineSegment);      // send graphics to display window
    glutMainLoop ();
}

Note: All code pasted here is free to be used in any way.