I guess you could, but what would gain from it? You would already have processed the vertices, and if the triangle can be frustum culled then it will get clipped anyway before rasterization. If you're actually using tessellation to amplify geometry then it's definitely a win to set the tessellation factor to zero for patches that are back-facing or outside the frustum, since this will save you from having to do extra work in the tessellator and in the domain shader stage. But if you're not actually using the tessellation stages to tessellate, then there's not really any point.
well I got the idea after I saw this guy http://rastergrid.co...ometry-shaders/ using a geometry shader to do culling.Weird thing is,samples with stream out always run quite slow on my PC.I know it's a not a very high end gpu(ATI Mobility Radeon HD 5650),but so far from what I've seen,CPU frustum culling is more efficient than using the GPU to do it,or am I missing something?I think I need a vote of confidence before I decide which method to try to implement .Using a scene graph would definately be less of a headache,but if there's an efficient GPU culling technique out there,I'd be glad to learn about it.