This topic pertains only to applications developed in C++.

Single-Axis Effects

Setting up the direction for a single-axis effect is extremely simple because there is really nothing to specify. Put the DIEFF_CARTESIAN flag in the dwFlags member of the DIEFFECT structure, and set rglDirection to point to a single LONG containing the value 0.

The following code example sets up the direction and axis parameters for an x-axis effect:

DIEFFECT eff;
LONG     lZero = 0;                        // No direction
DWORD    dwAxis = DIJOFS_X;                // X-axis effect
 
ZeroMemory(&eff, sizeof(DIEFFECT));
eff.cAxes = 1;                             // One axis
eff.dwFlags = 
    DIEFF_CARTESIAN | DIEFF_OBJECTOFFSETS; // Flags
eff.rglDirection = &lZero;                 // Direction
eff.rgdwAxes = &dwAxis;                    // Axis for effect

Two-Axis Effects with Polar Coordinates

Setting up the direction for a polar two-axis effect is only a little more complicated. Set the DIEFF_POLAR flag in dwFlags, and set rglDirection to point to an array of two LONGs. The first element in this array is the direction from which you want the effect to come. The second element in the array must be 0.

The following code example sets up the direction and axis parameters for a two-axis effect coming from the east:

DIEFFECT eff;
LONG     rglDirection = { 90 * DI_DEGREES, 0 }; // 90 degrees from
                                                // north, that is,   east
DWORD    rgdwAxes[2] = { DIJOFS_X, DIJOFS_Y };  // X- and y-axis
 
ZeroMemory(&eff, sizeof(DIEFFECT));
eff.cAxes = 2;                                  // Two axes
eff.dwFlags = 
    DIEFF_POLAR | DIEFF_OBJECTOFFSETS;          // Flags
eff.rglDirection = rglDirection;                // Direction
eff.rgdwAxes = rgdwAxes;                        // Axis for effect

Two-Axis Effects with Cartesian Coordinates

Setting up the direction for a Cartesian two-axis effect is a little more complicated. Set the DIEFF_CARTESIAN flag in dwFlags, and again set rglDirection to point to an array of two LONGs. This time the first element in the array is the x-coordinate of the direction vector, and the second is the y-coordinate.

The following code example sets up the direction and axis parameters for a two-axis effect coming from the east:

DIEFFECT eff;
LONG     rglDirection = { 1, 0 };               // Positive x = east
DWORD    rgdwAxes[2] = { DIJOFS_X, DIJOFS_Y };  // X- and y-axis
 
ZeroMemory(&eff, sizeof(DIEFFECT));
eff.cAxes = 2;                                  // Two axes
eff.dwFlags = 
    DIEFF_CARTESIAN | DIEFF_OBJECTOFFSETS;      // Flags
eff.rglDirection = rglDirection;                // Direction
eff.rgdwAxes = rgdwAxes;                        // Axis for effect