   Drawing lines in world space
  I am currently using DrawPrimitive() to draw a line list. The problem is that this function works with screen space when I want to use 3d world space.any suggestions?   
  Hi asafpolt.The reason of your problem is not the DrawPrimitive call. If you want to draw things in 3D you have to supply some information to your device.    Because you are drawing in screen space now you are using either RHW for your vertex format or an Ortho Projection (most likely the first one).    To draw a 3D scene make sure you have a proper vertex definition. I mean your vertices definition must also include a z element.Check a DX tutorial on this. You can find a good tutorial on making 3D scenes here: www.32Bits.co.uk   