use OpenGL;

sub triangle {
    glBegin GL_TRIANGLES;
    glColor3f 1.0, 0.0, 0.0;
    glVertex2f 5.0, 5.0;
    glColor3f 0.0, 1.0, 0.0;
    glVertex2f 25.0, 5.0;
    glColor3f 0.0, 0.0, 1.0;
    glVertex2f 5.0, 25.0;
    glEnd;
};

glpOpenWindow;
glMatrixMode GL_PROJECTION;
glLoadIdentity;
gluOrtho2D 0.0, 30.0, 0.0, 30.0;
glMatrixMode GL_MODELVIEW;

glClear GL_COLOR_BUFFER_BIT;
triangle;
glpFlush;

glpMainLoop;