Drawing a line using openGL does not work
- by vikasm
I am a beginner in OpenGL and tried to write my first program to draw some points and a line. I can see that the window opens with white background but no line is drawn. I was expecting to see red colored (because glColor3f(1.0, 0.0, 0.0);) dots (pixels) and line. But nothing is seen. Here is my code.
void init2D(float r, float g, float b)
{
glClearColor(r,g,b,0.0);
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0.0, 200.0, 0.0, 150.0);
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_POINTS);
for(int i = 0; i < 10; i++)
{
glVertex2i(10+5*i, 110);
}
glEnd();
//draw a line
glBegin(GL_LINES);
glVertex2i(10,10);
glVertex2i(100,100);
glEnd();
glFlush();
}
int main(int argc, char** argv)
{
//Initialize Glut
glutInit(&argc, argv);
//setup some memory buffers for our display
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
//set the window size
glutInitWindowSize(500, 500);
//create the window with the title 'points and lines'
glutCreateWindow("Points and Lines");
init2D(0.0, 0.0, 0.0);
glutDisplayFunc(display);
glutMainLoop();
}
I wanted to verify that the glcontext was opening properly and used this code:
int main(int argc, char **argv)
{
glutInit(&argc, argv);
//setup some memory buffers for our display
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
//set the window size
glutInitWindowSize(500, 500);
//create the window with the title 'points and lines'
glutCreateWindow("Points and Lines");
char *GL_version=(char *)glGetString(GL_VERSION);
puts(GL_version);
char *GL_vendor=(char *)glGetString(GL_VENDOR);
puts(GL_vendor);
char *GL_renderer=(char *)glGetString(GL_RENDERER);
puts(GL_renderer);
getchar();
return 0;
}
And the ouput I got was:
3.1.0 - Build 8.15.10.2345
Intel
Intel(R) HD Graphics Family
Can someone point out what I am doing wrong ? Thanks.
