.. meta::
    :description: Code snippets ROI mask

How to use a ROI as mask for operation on Channel
=================================================

In this example we will use a ROI to mask a Channel.

..
    This example needs to be better defined


First create a example channel::

    from ORSModel import Channel
    channel = Channel()
    #set it sizes, since we use the default voxel size, the channel is for now 100 meter cube
    channel.setXYZTSize(100,100,100,1)
    channel.setXSpacing(0.01)
    channel.setYSpacing(0.01)
    channel.setZSpacing(0.01)
    #now the channel is 1 meter cube
    #initilize it for float32 data
    channel.initializeDataForFLOAT()
    #put some data in the channel
    channel.paintSphere(channel.getBox().getCenter(), channel.getBox().getDirection0Size()*0.5, 1, 0)
    #tell the channel that it data was modified (this can trigger event trapped by the UI)
    channel.setDataDirty()
    #publish it so that it is visible in the Object properties list
    channel.publish()

Second let's create a ROI of the same shape as the channel::

    from ORSModel import ROI, orsColor
    roi = ROI()
    roi.setInitialColor(orsColor(1,0,0,1))
    roi.copyShapeFromStructuredGrid(channel)
    channel.getAsROIWithinRangeInArea(1, 1, 0, 0, 0, channel.getXSize()*0.5, channel.getYSize()*0.5, channel.getZSize()*0.5, None, roi)
    roi.publish()

Third let's overwrite the channel with the roi::

    channel.overwriteValueWithROI(roi, -1)
    channel.setDataDirty()