Smooth Shaded Triangles

        glShadeModel(GL_SMOOTH);
        glBegin(GL_TRIANGLES);
        glColor3f(0.1, 0.2, 0.3);
        glVertex3f(0, 0, 0);
        glColor3f(0.4, 0.5, 0.6);
        glVertex3f(1, 0, 0);
        glColor3f(0.7, 0.8, 0.9);
        glVertex3f(0, 1, 0);
        glEnd();

• Notice that now we have a different color for each vertex.
• This is "Gouraud shading" - interpolates per-vertex colors across the polygon