IDirectSound3DBuffer8::SetVelocity Method

项目
09/10/2011

[The feature associated with this page, DirectSound, is a legacy feature. It has been superseded by WASAPI and Audio Graphs. Media Casting have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Media Casting instead of DirectSound, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The SetVelocity method sets the velocity of the sound source.

Syntax

HRESULT SetVelocity(
         D3DVALUE x,
         D3DVALUE y,
         D3DVALUE z,
         DWORD dwApply
)

Parameters

x
Value that specifies the x coordinate of the velocity vector, in meters per second by default. DirectSound may adjust these values to prevent floating-point overflow. D3DVALUE is defined as float.
y
Value that specifies the y coordinate of the velocity vector, in meters per second by default. DirectSound may adjust these values to prevent floating-point overflow. D3DVALUE is defined as float.
z
Value that specifies the z coordinate of the velocity vector, in meters per second by default. DirectSound may adjust these values to prevent floating-point overflow. D3DVALUE is defined as float.

dwApply
Value that specifies when the setting should be applied. This value must be one of the following:

Value	Description
DS3D_DEFERRED	Settings are not applied until the application calls the CommitDeferredSettings method. This allows the application to change several settings and generate a single recalculation.
DS3D_IMMEDIATE	Settings are applied immediately, causing the system to recalculate the 3D coordinates for all 3D sound buffers.

Return Value

If the method succeeds, the return value is DS_OK. If the method fails, the return value may be DSERR_INVALIDPARAM.

Remarks

Velocity is used only for calculating Doppler effect. It does not change the position of the buffer. For more information, see Doppler Effect.

The default unit of measurement is meters per second, but this can be changed by using the SetDistanceFactor method.

Requirements

Header: Declared in DSound.h.

Library: Use Dsound3d.dll.

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