A BMD Fusion Studio Fuse that probes an image for values

TestModifer.fuse

FuRegisterClass("TestModifier", CT_Modifier, {
   REGS_Name           = "TestModifier",
   REGS_Category       = "Modifiers",
   REGS_OpDescription  = "Test Modifier",
   REGID_DataType      = "Point",
   REGID_InputDataType = "Point",
    })
   

function Create()
   InForeground = self:AddInput("Foreground", "Foreground", {
      LINKID_DataType = "Image",
      INPID_InputControl = "ImageControl",
      LINK_Main = 1,
      INP_Required = true,
         })
   
   InLocator = self:AddInput("Locator", "Locator", {
        LINKID_DataType = "Point",
        INPID_InputControl = "OffsetControl",
        INPID_PreviewControl = "CrosshairControl",
      LINK_Main = 2,
    })

   OutValue = self:AddOutput("Output", "Output", {
      LINKID_DataType = "Point",
      LINK_Main = 1,   
      })
end

function CheckRequest(req)
   if (req:GetPri() == 0 ) then
      req:ClearInputFlags( InForeground , REQF_PreCalc)
   end
end

function Process(req)
   local pos = Point(0.5, 0.5)
   if not req:IsPreCalc() then
   local location = InLocator:GetValue(req)
   local img = InForeground:GetValue(req)
   local x = location.X * img.Width
   local y = location.Y * img.Height
   x = math.min ((math.max(x,0)), img.Width-1)
   y = math.min ((math.max(y,0)), img.Height-1)
   local p = Pixel()
   img:GetPixel(x,y, p)
   pos = Point(p.R, p.G)
   else
   local location = InLocator:GetValue(req)
   local img = InForeground:GetValue(req)
   local x = location.X * img.Width
   local y = location.Y * img.Height
   x = math.min ((math.max(x,0)), img.Width-1)
   y = math.min ((math.max(y,0)), img.Height-1)
   local p = Pixel()
   img:GetPixel(x,y, p)
   pos = Point(p.R, p.G)
   end
 

   OutValue:Set(req, pos)
end

Code example by Jacob Danell. Released with permission under an open-source Apache-2 license.