/* cc -g -Wall -Wextra -fsanitize=address robot.c -lGL -lglut -lGLU -o robot */
#include <stdio.h> /* for printf of glError */
#include <GL/glut.h>

void display(void) {
    glClear(GL_COLOR_BUFFER_BIT);

    // draw axis
    glLineWidth(2);
    glBegin(GL_POINTS);
        // y-axis
        glVertex2i(0, -100);
        glVertex2i(0,  100);

        // x-axis
        glVertex2i(-100, 0);
        glVertex2i( 100, 0);
    glEnd();

    glBegin(GL_TRIANGLES);
        // positive Y-axis head (left, right, top)
        glVertex2i(-10, 100);
        glVertex2i( 10, 100);
        glVertex2i(  0, 120);
    glEnd();

    printf("%s\n", gluErrorString(glGetError()));

    glFlush();
//    exit(0);
}

void reshape(int w, int h) {
    glViewport(0, 0, w, h);
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.0, w, 0.0, h);
    //glTranslatef(50, 50, 0);
}

int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(0);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(300, 200);
    glutCreateWindow(argv[0]);
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);

    glEnable(GL_LINE_SMOOTH);
    //glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);

    glClearColor(1.0, 1.0, 1.0, 1.0);
    glColor3f(1.0, 0.0, 0.0);
    reshape(300, 200);

    glutMainLoop();
    return 0;
}

/* vim: set sw=4 ts=4 et: */