Development of a simulation system of combination blocks for educating kids about three-dimensional modeling.

在本研究中，我们开发了一款寓教于乐的软件，用于在虚拟空间中教授儿童三维建模的基础知识。建模系统模拟组合玩具块。每个积木块可以通过6个方向与其他积木块相连；上，下，右，左，前，后。在正确拼接块的操作中，碰撞检测的计算成本最高。在第一个版本中，我们将块的形状限制为单元立方体的组合。通过将三维空间划分为多个立方体，大大降低了碰撞检测的成本。然后添加了使用轨迹球的视图旋转界面，以便同时控制物体位置和眼睛位置。在下一个版本中，块的表面被定义为三角形，就像一般的CG系统一样，以便显示弧形和圆形等弯曲块。并在每个块中添加定向边界框树（OBB）。在判断块之间的碰撞之前，先判断OBB树的重叠程度，从而实现快速的碰撞检测。在现实世界中，孩子们通过合作移动双手来组合和分离玩具块。然而，由于以前的系统只有一个鼠标，因此双手操作必须被一套单手操作所取代。因此，我们开发了双鼠标界面来模拟双手操作。此外，我们还设计了一种算法，可以使用两只老鼠将块块块分成两部分。该算法首先在两个块的中心创建一个分离平面，每个块由一个相关的鼠标选择。然后，在平面的每一侧，直接或间接连接到所选块的块被聚集到一个组中。最后，未连接到同一侧所选块的剩余块被合并到对面的组中。该算法正在实现中。

In this research, we developed edutainment software for teaching kids the basis of 3D modeling in virtual space. The modeling system simulates combination toy blocks. Each of the blocks can be united with another blocks by 6 directions ; up, down, right, left, front, and back.In operations for jointing blocks correctly, collision detection requires highest computing cost. At the first version, we limited shape of blocks to the combination of the unit cubes. By dividing 3D space into the unit cubes, cost of the collision detection was much reduced. Then view rotation interface that uses a track ball was added in order to control both object position and eye position at the same time.At the next version, surfaces of blocks were defined with triangles like a general CG system, in order to display curved blocks such as arcs and circles. And a tree of oriented bounding box (OBB) was added to each block. By judging overlap of the OBB trees before judging collision of blocks, fast collision detection was achieved.In the real world, kids combine and separate toy blocks by cooperatively moving both hands. However, the both hands operation had to be replaced a set of one hand operations, since the previous systems have only one mouse. Thus, we developed double mice interface to simulate the both hands manipulation.In addition, we contrived an algorithm for dividing an agglomerate of blocks to two parts using the two mice. The algorithm, at first, creates a separation plane at the center of two blocks each of which was selected by a related mouse. Then, at each side of the plane, blocks both directly and indirectly connecting to the selected block are gathered to a group. Finally, remaining blocks, which do not connect to the selected block of the same side, are merged to the group of the opposite side. This algorithm is in implementation.