A Fuse You Can Use

Hey all, long time no see. This will be a technical post and is meant for users of a wonderful software known as Fusion. No i'm not talking about Saddam and his alleged plot to nuke the world. We in the visual effects community use Fusion for a lot of techno-creative work and one of the things that you can do in Fusion is to write your own code, appropriately known as a Fuse.

This is my first and very basic attempt at writing a Fuse plug and was based on a discussion with my close colleague Deepak Dhawan, who heads the QE wing within our organization. Deepak was on the lookout for a way to switch multiple input streams/node trees to a single output. Such a functionality is seen in the Switcher node in Houdini and so I decided to give it a shot and attempt to write a Fuse plugin. Let me point out that you can attempt similar functionality by a combination of Dissolve nodes and a few expressions.

There are some macros available out there which use a concoction of Dissolves however call me plain old fashioned mad, but I like to script/program.

The first attempt produced a working prototype that switched between 4 channels but had a tiny flaw which required all four streams to be available or else the node would fail. A quick query and response from Chad Capeland and further pointers from Daniel Koch (eyeon) fixed the bug and here's the Fuse. Just copy paste the text, drop it in a file, call it Switcher.fuse and place the file gently in Fusion5.3/Fuses/eyeon/

--[[--
 Switcher 1.0 by Sachin B [mailme@sachinbhatnagar.com]
 This node switches between 4 input streams to a single output. Just connect upto 4 input trees/nodes and flick the switch.
 

Drop this file in X:Program FilesFusion 5.3 Fuseseyeon
 --]]--
 FuRegisterClass("Switcher", CT_Tool, {
 REGS_Name = "Switcher",
 REGS_Category = "Fuseseyeon",
 REGS_OpIconString = "Swtch",
 REGS_OpDescription = "Switcher",
 REG_OpNoMask = true,
 REG_NoBlendCtrls = true,
 REG_NoObjMatCtrls = true,
 REG_NoMotionblurCtrls = true,
 })

 function Create()
 InImage = self:AddInput("Input1", "Input1", {
 LINKID_DataType = "Image",
 LINK_Main = 1,
 INP_Required = false,
 })
 In2Image = self:AddInput("Input2", "Input2", {
 LINKID_DataType = "Image",
 LINK_Main = 2,
 INP_Required = false,
 })
 In3Image = self:AddInput("Input3", "Input3", {
 LINKID_DataType = "Image",
 LINK_Main = 3,
 INP_Required = false,
 })
 In4Image = self:AddInput("Input4", "Input4", {
 LINKID_DataType = "Image",
 LINK_Main = 4,
 INP_Required = false,
 })
 InSwitch = self:AddInput("Switch", "Switch", {
 LINKID_DataType = "Number",
 INPID_InputControl = "MultiButtonControl",
 INP_Default = 0,
 {MBTNC_AddButton = "1", MBTNCD_ButtonWidth = 1, },
 {MBTNC_AddButton = "2", MBTNCD_ButtonWidth = 1, },
 {MBTNC_AddButton = "3", MBTNCD_ButtonWidth = 1, },
 {MBTNC_AddButton = "4", MBTNCD_ButtonWidth = 1, },
 })
 OutImage = self:AddOutput("Output", "Output", {
 LINKID_DataType = "Image",
 LINK_Main = 1,
 })
 end

 function Process(req)
 local switch = InSwitch:GetValue(req).Value
 if switch == 0 then
 local img = InImage:GetValue(req)
 img:Use()
 OutImage:Set(req, img)
 else
 if switch == 1 then
 local img2 = In2Image:GetValue(req)
 img2:Use()
 OutImage:Set(req,img2)
 else
 if switch == 2 then
 local img3 = In3Image:GetValue(req)
 img3:Use()
 OutImage:Set(req,img3)
 else
 if switch == 3 then
 local img4 = In4Image:GetValue(req)
 img4:Use()
 OutImage:Set(req,img4)
 end
 end
 end
 end
 end