PN三角形在基于GPU曲面细分中的应用

摘要

Curved Point-Normal(PN) triangles or the similar PN quads are both efficient ways to enhance realism in 3D rendering through tessellating every input triangle or quad into smaller triangles based on tessellation factor and soften triangles’ shared edges by using Bezier techniques. With the support of tessellation in modern GPU(Graphic Processing Unit) architecture and graphics library (e.g. DirectX 10 and 11), the PN triangles or quads has neither special requirement on rendering pipeline nor modeling tools, and it can produce soft silhouette and efficient rendering result by using vertex position, normal information, adaptable Load of Detail(LoD), and possible Normal Map or Displacement Map.%为了增强模型渲染的真实感，本文使用曲面点-法线(PN)三角形或四边形(原理与三角形类似)来细化和调整输入模型中的三角形或四边形面片，从而实现棱角的柔和化。在 GPU(图形处理器)管线和图形库(如 DirectX 10和11)支持细分的前提下，该技术能适用于现有的渲染管道结构，并且对建模工具也没有特别的要求，仅基于顶点位置和法线信息便可渲染出圆润的轮廓，同时使用自适应细节层次(LoD)技术，提高了渲染的效率，再加上法线贴图和置换贴图的应用，可渲染出外形贴近真实且更具质感的效果，因而具有一定的实用价值。