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.