cannot read data of a SoObliqueSlice

[lilly_li]

Dear Mike,

I've tried to get the data of the palne of SoObliqueSlice. The code is as belows:

SbPlane plane;
SbVec3f planePosition = mpDragger->translation.getValue(); // plane clip dragger
SbRotation rotation = mpDragger->rotation.getValue();
SbVec3f planeNormal;
rotation.multVec( SbVec3f(0,1,0), planeNormal );
plane = SbPlane( planeNormal, planePosition );

SbVec3i32 volDim = mpVolume3D->data.getSize();
SbBox3i32 box;
box.setBounds( 0, 0, 0, volDim[0] - 1, volDim[1] - 1, volDim[2] - 1 );
SoVolumeData::LDMDataAccess:ataInfoPlane info;
SoLDMDataAccess& dataAccess( mpVolume3D->getLdmDataAccess() );
SoDataSet* DS = dataAccess.getDataSet();
SoDataSet:ataType DT = DS->getDataType();
//query size of data buffer
info = mpVolume3D->getLdmDataAccess().getData( 0, box, plane );

SoRef<SoCpuBufferObject> bufferObj = new SoCpuBufferObject;
if ( info.bufferSize )
{
bufferObj->setSize(info.bufferSize);
info = dataAccess.getData( 0, box, plane, bufferObj.ptr());
if ( !(info.errorFlag == SoVolumeData::LDMDataAccess::CORRECT) )
SoError:ost("Error while data access request");

SbVec2i32 buffDim = info.bufferDimension;
int buffSize = info.bufferSize;
int32_t nx,ny,nz;
buffDim.getValue(nx,ny);
int buffElements = nx*ny;

SoVolumeHistogram aHisto(DT);
aHisto.setInputValueRange( mOriDataMinValue, mOriDataMaxValue );
aHisto.addValues(bufferObj.ptr(),buffElements);

size_t numBins = aHisto.getHistoSize();
int64_t* hvalues = aHisto.getHistogram();
}

The problem is that info.bufferSize is 0, meaing it failed to get data. Would you please tell me why?

[mikeheck]

I've tried to get the data of the palne of SoObliqueSlice. The code is as belows:

    SbPlane plane;
    SbVec3f planePosition = mpDragger->translation.getValue(); // plane clip dragger
    SbRotation rotation = mpDragger->rotation.getValue();
    SbVec3f planeNormal;
    rotation.multVec( SbVec3f(0,1,0), planeNormal );
    plane = SbPlane( planeNormal, planePosition );

The problem is that info.bufferSize is 0, meaning it failed to get data. Would you please tell me why?

I can't say for sure. I tried a quick test with your code, setting the plane at the center of the volume (arbitrary valid position) and it worked fine.

So one possible problem is that the plane you're computing from the dragger is outside the bounds of the volume. In this case the value returned in info.errorFlag should be INCORRECT_PLANE.

[lilly_li]

error flag is CORRECT

I checked the errorFlag. It is 0 ( CORRECT ).

[mikeheck]

I checked the errorFlag. It is 0 ( CORRECT ).

OK, it's strange that the buffer size is zero if errorFlag is zero and the plane intersects the volume. I did confirm that your data access code is OK (it works in a test program for me). But I don't know what plane is being returned by your dragger. Can you submit a simple test case?
If not, can you send the volume dimensions, the volume extent in 3D and the values in the SbPlane parameter you're passing to the getData() function?

[lilly_li]

pars and sorry for reply so so late.

Dear Mike,

Sorry to reply so late.

the extent of the volume data is x: 3800-4600, y : 0 - 22542.9, z: 0 - 11026.1

the plane normal is : 0, 0, 1 and the position is 4200, 11271.4, 5515.05