Summary: The tessellation level limit of semi-uniform adaptive patch tessellation is \(2^n\). It is less adaptive. Even patch tessellation is proposed using vertex fitting function to increase tessellation level limit from \(2^n\) to \(2n\). Vertex moving is controlled by controlling function on vertex shader to eliminate the boundary cracks. In addition, the parameter region is divided to avoid floating point precision issue caused by direction inconsistency of function coordinate axes. Then, parametric mesh layouts are 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.