3D Slices - Interactive Slices
The "Slicing plane" is a "3D Coordinate Plane" variable, and is used here as a slicer. The drawing command that was created when the mesh was dragged into the drawing window takes in a number or list of numbers to slice the mesh. Remove that drawing command by dragging it to the trash.
Create a "Mesh Slice" drawing command and drag the mesh and coordinate plane on top to connect those variables. You can also select them from the pop-up menus.
By clicking on the "Now" button the current value range of the entire 3D mesh is inserted into the range field. This will be used to determine the coloring range for the color ramp. The color ramp is specified in the line above. Here the ramp is specified inline, but there is also a "Color Ramp" variable.