week02

 glBegin(GL_POLYGON); ///要畫的東西是三角形
    glColor3f(1,0,0); glVertex2f(1,0); ///顏色+向量
    glColor3f(0,1,0); glVertex2f(-1,1);
    glColor3f(0,0,1); glVertex2f(-1,-1);
 glutSwapBuffers();