glTest.c

#include <OpenGL/gl3.h>
#include <GLUT/glut.h>

void init(){
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0, 200, 0, 150);
}

void lineSegment(){
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1, 0, 0);
    glBegin(GL_LINES);
        glVertex2i(180, 15);
        glVertex2i(10, 145);
    glEnd();
    glFlush();
}
int main(int argc, char *argv[]){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowPosition(50, 100);
    glutInitWindowSize(400, 300);
    glutCreateWindow("test");

    init();

    glutDisplayFunc(lineSegment);
    glutMainLoop();
}