用maya制造环形跑道模型和材质（英文）

(16) In the Hypershader create three lambert shader groups using the 3 textures. In the Place2dTexture node change the V repeat value to 16. This will ensure that per 128m surface section, the texture will tile 16 times – in other words each texture will cover two spans on the surface in the V direction.

　　

　　(17) But what about the other sections of 32m, 64m, and 96m? Simple – just create three duplicates of each shader group and change the repeats to 4, 8, and 12 respectively. Its useful to use a naming convention for each so its easy to differentiate, e.g. Tarmac16, Tarmac12, Tarmac8 and Tarmac4.

　　

(18) The next step is to assign each shader to the relevant sized surface. At this point you may need to use the Reverse Surface Direction Options found in the Edit NURBS menu. Alternatively you can modify the UVs later once the NURBs have been converted to polys.

　　

　　ADDING ENVIRONMENT (19) Time to convert to polygons at last! Use the Convert NURBS to Polygons Options found in the Modify menu. Make sure the Type is set to Quads, Tesselation Method is set to General, and the Initial Tesselation Controls are set to Per Span 1 of Iso Params.