From: Gil Gribb <ggribb@ra...>  20010331 00:38:54

> I suspect Mark's matrix is not a standard one. It should not matter. The derivation only relies on the clip space inequaties. There is no assumtions on the matrices at all. I'd like to see some numbers to diagnose the problem. Gil > > Well, it comes down to the question "what are the z clip space inequalties > > for D3D?" > > [...] > > But then I thought they changed them to: > > w<z<w > > It is definitely 0<z<w.. > Just take the matrix from "what is the projection transformation" help page, > if you want to be sure, and transform [0,0,Zn,1] > > On the other hand, open gl, and "some hardware with a nice clipping > instruction" use the w<z<+w convention.. Switching from one system to > another was a real pain for my brain :) > > > But I really don't know. You said near was working, but far was not. If > > that is the case then both of these are the same for zfar. What numbers > > are you getting? > > It works like a charm if you use a "standard'" projection matrix.. > > I suspect Mark's matrix is not a standard one; that it includes a > transformation from a righthanded world into d3d left handed > coordinate system. If so, flipping z should be enough to get the > (not yet normalized) far plane equation.. > > Basically, it means that instead of C=C4C3 for C.V, you have > C.x=C4.xC3.x > C.y=C4.yC3.y > C.z=C3.zC4.z < here > C.w=C4.wC3.w > > Nicolas > > > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > http://lists.sourceforge.net/lists/listinfo/gdalgorithmslist 