The primary use of obstacle constraints is to allow the user to “sculpt” the final structure intuitively while preserving realism, but they can also serve to produce novel structures by creating local optima. Figure 6 shows, from left to right, an initial structure, infeasible because it violates the obstacle avoidance constraint, and two designs produced as solutions from slightly different (random) initial guesses for ~ l . In each image, the red sphere is the volume to be avoided, the green sphere at the top is the load that must be supported, and the cylinders are the beams, colored cyan or tan depending on whether they are in compression or tension. The anchors are located at the three points where the structure touches the ground.