Working with visualisation tools : Layers : Spatial input layer

Spatial input layer

This layer helper allows spatial input to be sent to a model during execution. When it is added as a layer, the modeller is requested to select three variable parameters from the model. These must be scalar with numerical units.

The first two of these will hold the X and Y coordinates of a position in the field of view of the layer tool. They are not changed until the modeller clicks or drags within the tool. At that point they will be continually updated with the pointer position within the layer tool until the unclick. The final variable is set to zero at any time when a click or drag is not in progress. It is set to 1 when a click occurs and is incremented by 1 whenever the pointer coordinates change during a drag. This is so the model can keep track of the speed or duration of the drag. It is set to zero again on the unclick.

This tool does not itself display anything within the layer helper area. Normally it would be added to a layer tool which is also showing a spatial grid covering the area in which the coordinates could be expected to fall, so the tool could be 'zoomed to fit' resulting in the input pointer layer also extending over the right range of coordinates. If there is no actual grid to display, the area covered by the input tool could be set by adding four 'line' layers, each with a single line corresponding to one side of the rectangle containing the desired input coordinates. These coordinates could be entered directly to the layer tool as numbers, or got from model variables.