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schupf

D3DDECLUSAGE_POSITION

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Hi,

I have just read the DX9 Documentation about vertex declarations:
http://msdn.microsoft.com/en-us/library/bb172534%28v=VS.85%29.aspx

I am kinda surprised by their information about D3DDECLUSAGE_POSITION:
[quote]
D3DDECLUSAGE_POSITION

Position data ranging from (-1,-1) to (1,1). Use D3DDECLUSAGE_POSITION with a usage index of 0 to specify untransformed position for fixed function vertex processing and the n-patch tessellator. Use D3DDECLUSAGE_POSITION with a usage index of 1 to specify untransformed position in the fixed function vertex shader for vertex tweening.[/quote]
Why should a vertex position element (mostly float3) be limited to (-1,-1) to (1,1)? I always thought
D3DDECLUSAGE_POSITION means: An untransformed position. So it could be anything like (33,44,-11.22).

Do I miss something or is this documentation really misleading?

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You're not limited to [-1, 1], I have no idea why the documentation says that. In fact as far as I know, you're not limited to any range for any vertex declaration usage. You're only limited to the range and precision of the format specified by the D3DDECLTYPE you specify.

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