Drawing curve in directX

What is this curve for? If its a simple circle or oval you are after it is easier. Also is this needed in 2D or 3D space?

ace

D3DXVec3CatmullRom is a very handy function. You just pass in the control points of your curve and it calculates interpolated intermediate points for you.

You can use a line-strip to render the output (no matter whether it's 2D or 3D).

If you need more info, just ask.

Regards,
Pat

Well, the task is a bit hard. I have to draw a set of isolines (curves) onto the screen by given points. Everything will be in 2d space, but i will have to represent z value by drawing these curves.
My other question would be: i pass four points to D3DXVec3CatmullRom, but i get only one point back, so how can i draw (sorry, my english is shit :)) more realistic curves, i mean how can i get more points? Do i have to call it recursively to obtain requred number of points, or there is other solutions?
Are there any better interpolation functions in DX?

Quote:

Original post by transcendent_one My other question would be: i pass four points to D3DXVec3CatmullRom, but i get only one point back, so how can i draw (sorry, my english is shit :)) more realistic curves, i mean how can i get more points? Do i have to call it recursively to obtain requred number of points, or there is other solutions?

Yup, you call it repeatedly. The last paremter s is the weighting factor. You call the function as many times as you want, passing a larger s each time. For example, you could call it 5 times with s = 0.0f, 0.25f, 0.5f, 0.75f and 1.0f to give you 5 points along the curve.

From the DX9 docs:

Quote:

Given four points (p1, p2, p3, p4), find a function Q(s) such that: Q(s) is a cubic function. Q(s) interpolates between p2 and p3 as s ranges from 0 to 1. Q(s) is parallel to the line joining p1 to p3 when s is 0. Q(s) is parallel to the line joining p2 to p4 when s is 1.

Edit: This might help:

The red lines are immaginary, the black line is the generated spline. I'm not entirely sure that I've got that right, someone feel free to correct me if I'm wrong.

Thanks guys. There's one more question, are there any directx online tutorials or samples how to implement curve drawing? I tried to google but coulndt find anythig useful.

Thanks again.