# FFEffectGetParameters(_:_:_:) Retrieves information about an effect. ``` func FFEffectGetParameters(_ effectReference: FFEffectObjectReference!, _ pFFEffect: UnsafeMutablePointer!, _ flags: FFEffectParameterFlag) -> HRESULT ``` ## Parameters `effectReference` An opaque reference handle to an effect object. This is obtained from a previous call to FFDeviceCreateEffect. `pFFEffect` Address of a FFEFFECT structure that receives effect information. The dwSize member must be filled in by the application before calling this method. `flags` Flags that specify which parts of the effect information are to be retrieved. The value can be 0 or one or more of the following constants: FFEP_ALLPARAMS The union of all other FFEP_* flags, indicating that all members of the FFEFFECT structure are being requested. FFEP_AXES The cAxes and rgdwAxes members should receive data. The cAxes member on entry contains the size (in DWORDs) of the buffer pointed to by the rgdwAxes member. If the buffer is too small, the method returns FFERR_MOREDATA and sets cAxes to the necessary size of the buffer. FFEP_DIRECTION The cAxes and rglDirection members should receive data. The cAxes member on entry contains the size (in DWORDs) of the buffer pointed to by the rglDirection member. If the buffer is too small, the GetParameters method returns FFERR_MOREDATA and sets cAxes to the necessary size of the buffer. The dwFlags member must include at least one of the coordinate system flags (FFEFF_CARTESIAN, FFEFF_POLAR, or FFEFF_SPHERICAL). The API returns the direction of the effect in one of the coordinate systems you specified, converting between coordinate systems as necessary. On exit, exactly one of the coordinate system flags is set in the dwFlags member, indicating which coordinate system the FF API used. In particular, passing all three coordinate system flags retrieves the coordinates in exactly the same format in which they were set. FFEP_DURATION The dwDuration member should receive data. FFEP_ENVELOPE The lpEnvelope member points to a FFENVELOPE structure that should receive data. If the effect does not have an envelope associated with it, the lpEnvelope member is set to NULL. FFEP_GAIN The dwGain member should receive data. FFEP_SAMPLEPERIOD The dwSamplePeriod member should receive data. FFEP_STARTDELAY The dwStartDelay member should receive data. FFEP_TRIGGERBUTTON The dwTriggerButton member should receive data. FFEP_TRIGGERREPEATINTERVAL The dwTriggerRepeatInterval member should receive data. FFEP_TYPESPECIFICPARAMS The lpvTypeSpecificParams member points to a buffer whose size is specified by the cbTypeSpecificParams member. On return, the buffer is filled in with the type-specific data associated with the effect, and the cbTypeSpecificParams member contains the number of bytes copied. If the buffer supplied by the application is too small to contain all the type-specific data, the method returns FFERR_MOREDATA, and the cbTypeSpecificParams member contains the required size of the buffer in bytes. ## Return Value If the method succeeds, the return value is FF_OK. If the method fails, the return value can be one of the following error values: ## Discussion FFERR_INVALIDPARAM FFERR_NOTDOWNLOADED FFERR_MOREDATA ## Discussion Common errors resulting in a FFERR_INVALIDPARAM error include not setting the dwSize member of the FFEFFECT structure, passing invalid flags, or not setting up the members in the FFEFFECT structure properly in preparation for receiving the effect information. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)