Platform SDK: DirectX |
The DICONDITION structure contains type-specific information for effects that are marked as DIEFT_CONDITION.
A pointer to an array of DICONDITION structures for an effect is passed in the lpvTypeSpecificParams member of the DIEFFECT structure. The number of elements in the array must be either one, or equal to the number of axes associated with the effect.
typedef struct DICONDITION { LONG lOffset; LONG lPositiveCoefficient; LONG lNegativeCoefficient; DWORD dwPositiveSaturation; DWORD dwNegativeSaturation; LONG lDeadBand; } DICONDITION, *LPDICONDITION; typedef const DICONDITION *LPCDICONDITION;
If the device does not support separate positive and negative coefficients, the value of lNegativeCoefficient is ignored, and the value of lPositiveCoefficient is used as both the positive and negative coefficients.
If the device does not support force saturations, the value of this member is ignored.
If the device does not support force saturation, the value of this member is ignored.
If the device does not support separate positive and negative saturation, the value of dwNegativeSaturation is ignored, and the value of dwPositiveSaturation is used as both the positive and negative saturation.
Different types of conditions interpret the parameters differently, but the basic idea is that force resulting from a condition is equal to A(q - q0) where A is a scaling coefficient, q is some metric, and q0 is the neutral value for that metric.
The preceding simplified formula must be adjusted if a nonzero dead band is provided. If the metric is less than lOffset - lDeadBand, the resulting force is given by the following formula:
force = lNegativeCoefficient * (q - (lOffset - lDeadBand))
Similarly, if the metric is greater than lOffset + lDeadBand, the resulting force is given by the following formula:
force = lPositiveCoefficient * (q - (lOffset + lDeadBand))
A spring condition uses axis position as the metric.
A damper condition uses axis velocity as the metric.
An inertia condition uses axis acceleration as the metric.
If the number of DICONDITION structures in the array is equal to the number of axes for the effect, the first structure applies to the first axis, the second applies to the second axis, and so on. For example, a two-axis spring condition with lOffset set to 0 in both DICONDITION structures would have the same effect as the joystick self-centering spring. When a condition is defined for each axis in this way, the effect must not be rotated.
If there is a single DICONDITION structure for an effect with more than one axis, the direction along which the parameters of the DICONDITION structure are in effect is determined by the direction parameters passed in the rglDirection field of the DIEFFECT structure. For example, a friction condition rotated 45 degrees (in polar coordinates) would resist joystick motion in the northeast-southwest direction but would have no effect on joystick motion in the northwest-southeast direction.
Windows NT/2000: Requires Windows 2000.
Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
Header: Declared in dinput.h.