| Terrain is a common three-dimensional scene, and it is also an important part of the three-dimensional scene, real-time drawing of terrain data on the PC side has a lot of research, but in order to achieve real-time rendering of large-scale of terrain on mobile is still a new issue. At present, the hardware performance of mobile device developed rapidly, and the mobile terminal terrain rendering mostly are in remote mode, the terrain in the local drawing mode has less research.With limited resources in the mobile terminal device, to achieve terrain drawing algorithm on local drawing mode is the main content of this paper. In order to decrease I / O operations to reduce processing time to improve rendering efficiency in the terrain data loading stage, first decompress the larger part of the terrain data into the memory of mobile terminal, and then construct LOD structure of terrain data based Geometry Clipmap algorithm,and organized the terrain data based on the Quadtree data structure; according to the viewpoint’s level and position where in the LOD structure combined with the L-update to reconstructed the terrain data after change the position of viewpoint, then using the vertex index which in vertex buffer to draw out different terrain effects, make full use of mobile terminal hardware, improve drawing efficiency.In the interaction on the mobile devices, we designed the different interaction effects achieved the rotating and moving operations to rending terrain data according the mobile terminal operating gesture habits. This paper combined with OpenGL ES 2.0 and NDK developed the terrain data drawing system for Android based on the above strategy. And tested the Puget Sound terrain and Xin Jiang terrain data on the Samsung N9100 mobile phone and the Samsung P600 tablet, the result achieve the designed effect. |
