自适应偶数曲面细化

针对二分半规则曲面细化自适应性不足的缺陷,提出一种新的自适应偶数曲面细化方法,通过在顶点着色器中设计新的顶点调控函数控制顶点偏移,解决边界裂缝问题;并采用参数区域划分子区域的方法,解决函数坐标轴方向不一致引起的浮点误差问题,将细化因子集合从2n扩展到2n形式;利用偶数细化层次递增关系,优化参数几何数据布局,达到层次间顶点和索引双重用. 实验分析表明,在同等细化测度下,本文方法细化因子更接近于细化测度,曲面细化过渡更匀称,绘制面片规模由幂指数级降到线性级,绘制性能提高在20%以上,是一种可行有效的硬件网格细化模式扩展. 

Adaptive Even Patch Tessellation

The tessellation levels limit of semi-uniform adaptive patch tessellation is 2ⁿ. It is less adaptive. Even patch tessellation was proposed using vertex fitting function to increase tessellation levels limit from 2ⁿ to 2n. Vertex moving was controlled by controlling function on vertex shader to eliminate the boundary cracks. In addition, parameter region was divided to avoid floating point precision issue caused by direction inconsistency of function coordinate axes. Then, parametric mesh layouts were optimized, and both vertex and index can be reused between different tessellation levels. The results show that even tessellation is more adaptive than dyadic tessellation under the same tessellation metric. The number of polygons rendered reduced to about 60% of that in dyadic tessellation, and rendering frames per second is increased by more than 20%. Our method expands existing hardware tessellation pattern.