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Constantin

CreateDevice affects floating point computation of Old C++ program

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I have a very Old C++ program with floating point operations that do some rounding off of numbers. Adding a call to CreateDevice seems to give these operations a higher level of precision which screws up some rounding computations. Is there anything I do?

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look up

_control87
_controlfp
__control87_2

and other related floating point control functions (e.g., _fpreset) in your windows sdk help

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As AnAss implied, you need to pass the D3DCREATE_FPU_PRESERVE flag to CreateDevice. D3D changes the floating point state when you call CreateDevice, unless that flag is set, although using that flag will reduce performance.

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