![]() ![]() Without tessellation, vertex shader normally outputs at least clip space position. Of course it is necessary to adjust your shader code in VS. By binding those shaders in the context, tessellation will be enabled. To enable it, you need to create a valid hull shader and domain shader. There is no specific functions to enable tessellation. Tessellation gives the perfect result, the rocks look really bumpy here.īefore diving into the details, let’s see how to enable tessellation through the API. SPOM can solve the problem, however it is far beyond the topic of this blog. POM solves the problem with a ray marching method, however it still shows artifacts at the silhouette of objects. The left one is normal map, the quality quickly breaks down when viewed at a wide angle. Here is a comparison between tessellation, POM and normal map, those captures come from the detail tessellation demo from D3D SDK. Of course it can just pass the vertices to the next stage if this is what is needed. And it is also responsible for generating vertices in clip space, like VS does without tessellation enabled. Whether it is phong tessellation, PN or flat tessellation is decided here. It is programmer’s job to evaluate the final clip space position with the intermediate data in the barycentric coordinate.ĭomain shader is the place for calculating the positions of generated vertices. One thing to be noted is that the vertices generated in tessellator are located in barycentric coordinate. ![]() It generates those tessellated triangles under the hood and feeds them with the constant data to the next stage, domain shader. It can’t be programmed directly and neither can it be setup through API interfaces, it is affected by tessellation factors, the output of hull shader (or TCS in OpenGL). And they both take in control points and generate some tessellation factors and per-patch constant data. Anyway, they are still pretty similar to each other. In OpenGL 4, it is called tessellation control shader and there is no extra per-patch constant function. There are two different functions in Hull Shader, one is the hull shader itself and the other is the constant function which runs on a per-patch basis. There are three stages right after vertex shader, hull shader, tessellator and domain shader with each stage performing separate functionality. Tessellation is a new feature that enables graphics programmer to tessellate their triangles on the fly so that the geometry detail will be enriched. What is tessellation? This should be a question to be addressed first before everything. In this article, I’d like to mention some detail that I learned about tessellation. Since tessellation factors, which determines how to tessellate the object, are calculated on the fly during rendering, level of detail can be decided based on factors like distance, angle, etc. It saves a lot of time by placing intense computation, like bone matrix multiplication, in vertex shader which only processes control points of the model. Less calculation on full detailed model.Combined with displacement map, tessellation can produce bump surfaces in a much more realistic way than what can be achieved with normal map or POM. With phong tessellation, it smoothes the silhouette so that no sharp edge corner will be visible. One of the most important changes that DX11 has made is the brand new feature called tessellation. By introducing three more stages, graphics programmer can tessellate their triangles on the fly. ![]()
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