DirectX 11 上的 NURBS？
可以使用 DirectX 11 在 GPU 上渲染 NURBS 吗？我一直在研究渲染此类曲面的当前趋势，但我在 NURBS 上没有看到任何内容。
我找到了一些相关的参考文献，但没有任何可靠的参考文献......比如 Charles Loop 和 Scott Schaefer 的“Approximating Catmull-Clark Subdivision Surfaces with Bicubic Patches”。
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Can you render NURBS on the GPU with DirectX 11? I've been reading up on current trends to rendering surfaces like these, but I don't see anything on NURBS.
I found some related references, but nothing solid... like "Approximating Catmull-Clark Subdivision Surfaces with Bicubic Patches" by Charles Loop and Scott Schaefer.
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DirectX SDK中有2个演示； SubD10、SubD11 分别用于 DirectX 10/11 实现本文中描述的技术。
There are 2 demos in the DirectX SDK; SubD10, SubD11 for DirectX 10/11 implemenations respectively of the techniques described in this article.
快速回答是否定的。 NURBS 非常复杂，编写一个可以在 GPU 上渲染它们的高效着色器是很困难的。我认为这是可能的，但通常不会这样做，因为有更好的方法。
更好的方法是直接在 GPU 上渲染 Bézier 面片，因为任何 NURBS 都可以转换为一组连接的 Bézier 面片。为了生成补丁，您需要在每个结处执行结插入，直到它达到与度数相同的重数；例如，在立方 NURBS 上，您将在每个结处执行结插入，直到每个结都是三重结。然后，NURBS 的控制点可以被视为连接的贝塞尔网格。
这存在一个特定于着色器的问题：当您对 Bézier 面片进行三角测量时，共享边界的面片也共享完全相同的曲面细分设置至关重要，否则由于曲面细分不匹配，NURBS 曲面中会出现裂纹。如果您使用固定的曲面细分设置，这不是问题，但如果您使用依赖于视图的曲面细分，则需要确保每个面片边界都有独立计算的“视图相关”曲面细分，以便相邻面片匹配。
The quick answer is no. NURBS are pretty complex, and it would be difficult to write an efficient shader that can render them on the GPU. I think it's possible, but it isn't usually done because there's a better way.
The better way is to render Bézier patches directly on the GPU, since any NURBS can be converted into a connected set of Bézier patches. To generate the patches, you perform knot insertion at every knot until it hits the same multiplicity as the degree; e.g. on a cubic NURBS, you would perform knot insertion at every knot until every knot is a triple knot. The control points of the NURBS can then be treated as a connected Bézier mesh.
There is a problem with this, specific to shaders: When you triangulate your Bézier patches, it's critical that patches which share a boundary also share the exact same tessellation settings, or there will be cracks in your NURBS surface due to tessellation mismatch. If you use fixed tessellation settings, this isn't a problem, but if you use view-dependent tessellation, then you need to make sure that each patch boundary has its "view dependent" tessellation calculated independently, so that adjacent patches will match.