'
'----------------------------
'--- Creation information ---
'----------------------------
'
'Name: calcvol.ave
'Version: 1.0
'Date: 02/07/97
'Author: Ferdi Hellweger
'        Center for Research in Water Resources
'        The University of Texas at Austin
'        ferdi@crwr.utexas.edu
'
'---------------------------
'--- Purpose/Description ---
'---------------------------
'
'This program computes the volume.
'
'---------------------------------------------
'--- Check if units configuration happened ---
'---------------------------------------------
'
if (not _configu) then
    configure = msgbox.yesno("Units are not configured.  Configure it now?","BALANCE",true)
    if (configure) then
        av.run("balconu", nil)
    else
        exit
    end
end
'
'----------------
'--- Get view ---
'----------------
'
theview = av.getactivedoc
'
'-----------------
'--- Get theme ---
'-----------------
'
theactivethemes = theview.getactivethemes
if (theactivethemes.count = 0) then
    msgbox.error("No active themes found", "BALANCE")
    exit
end
if (theactivethemes.count > 1) then
    msgbox.error("Too many active themes found", "BALANCE")
    exit
end
theptheme = theactivethemes.get(0)
pftab = theptheme.getftab
pshapef = pftab.findfield("shape")
pshape = pftab.returnvalue(pshapef,0)
if (not (pshape.getclass.getclassname = "polygon")) then
    msgbox.error("The theme needs to be a polygon theme", "BALANCE")
    exit
end
'
'--------------------
'--- Set up theme ---
'--------------------
'
hf = pftab.findfield("h")
if (hf = nil) then
    addfield = msgbox.yesno("Can't find 'h' field in polygon theme.  Add it?","BALANCE", true)
    if (addfield) then
        pftab.seteditable(true)
        hf = field.make("h", #FIELD_DECIMAL, 16, 4)
        pftab.addfields({hf})
        pftab.seteditable(false)
    else
        exit
    end
end
'
vf = pftab.findfield("v")
if (vf = nil) then
    addfield = msgbox.yesno("Can't find 'v' field in polygon theme.  Add it?","BALANCE", true)
    if (addfield) then
        pftab.seteditable(true)
        vf = field.make("v", #FIELD_DECIMAL, 16, 4)
        pftab.addfields({vf})
        pftab.seteditable(false)
    else
        exit
    end
end
'
'-----------------
'--- Calculate ---
'-----------------
'
'--- Initial set up ---
'
'make polygon attribute table editable
'
pftab.seteditable(true)
'
'--- Loop ---
'
for each prec in pftab
    '
    'get depth
    '
    h = pftab.returnvalue(hf, prec)
    '
    'calculate area
    '
    pshape = pftab.returnvalue(pshapef, prec)
    lshape = pshape.aspolyline
    mpoint = lshape.asmultipoint
    plist = mpoint.aslist
    n = plist.count
    i = 1
    a = 0
    for each prec in plist
        yterm = plist.get(i - 1).gety 
        if (i < n ) then
            xterma = plist.get(i).getx
        end
        if (i = n ) then
            xterma = plist.get(0).getx
        end
        if (i > 1) then
            xtermb = plist.get(i - 2).getx
        end
        if (i = 1) then
            xtermb = plist.get(n - 1).getx
        end
        a = a + (yterm * (xterma - xtermb))
        i = i + 1
    end
    a = 0.5 * a.abs
    '
    'calculate volume
    '
    v = a * h
    '
    'write v to polygon attribute table
    '
    pftab.setvalue(vf, prec, v)
    '
end
'
'make polygon attribute table non editable
'
pftab.seteditable(false)
'
'final message to user
'
message = "Volume, v calculated"
msgbox.info(message,"BALANCE")
'
'-----------
'--- End ---
'-----------
'