What Is a Polynomial?

In Conclusion

You have just seen how you can render patches very simply using DirectX. The simplicity might make DirectX patches very attractive, but hardware acceleration can be a double-edged sword. I envision most projects falling into one of three categories. You might be able to use DirectX all the time, you might not be able to use it at all, or you might want to use it for rendering, but do your own calculations for physics, legacy support, or some other reason.

In any case, remember that you have several tools available to you. You should always spend time evaluating your tools and choose the right one for the right job. When you do that, here are a couple of points to remember.

• DirectX offers hardware support for rectangle and triangle patches. If the user has the right hardware, they can be very fast.

• The DirectX patches offer you simplicity at the cost of control. You must evaluate your needs to see if they make sense for you.

• The patch info structures allow you to define patches based on concepts you already know from the earlier text. Even if you do use the DirectX solution, it still makes sense to understand the different orders and basis types.

• In addition to the position calculations, DirectX will also calculate the normals if you set up the proper vertex declaration. You can control vertex lighting with either the fixed-function pipeline or a vertex shader.

• I have deliberately ignored changes that are present in DirectX 9.0 or OpenGL. Make sure you check the documentation to see how surfaces are supported in other APIs.