One of the handy building blocks to have in your arsenal as you’re working with any media system is an understanding of how it works with system folders. Isadora, for example, pulls assets from the folder specified when you load the original file. This means that you can change an asset, save it with the same name and in placing it in the proper system folder your changes show up without having to re-import any files. What then, if I want to automatically pull files from a folder on my computer? In TouchDesigner that’s a relatively simple thing to accomplish without too much work. Better yet, the underlying principles open up a lot of much more interesting possibilities.
Alright, let’s start with a simple problem that we can solve with TouchDesigner. I want to build a simple patch where I can use two control panel buttons to navigate through a list of images (or movies) in a specified folder – essentially I want to be able to add my photos or videos to a folder on my computer, and then display them in TouchDesigner without having to drag them into the network or having to add a Movie-In TOP.
Let’s start by looking at the full network.
Our system is made of three strings – a series of CHOPs, a series of DATs, and a TOP. We’re going to use two buttons to control a series of channel operators to give us a number. We’re going to use this number to select a specific file from a folder, and then we’re going to use that file name in a Movie-In Texture Operator to be displayed.
Let’s start with our CHOP string.
Button – Trigger – Count – Math – Null
First things first, the important place to start in this particular string is actually in the middle at the Count CHOP. The Count CHOP, in this case, is going to watch for a change in a signal and use that as a mechanism for determining when to increment or reset. There are lots of different ways to count, but in this particular case the Count CHOP is an excellent method for incrementing from a button press. Alright, so if we know that we’re going to start with a count, then we don’t actually need the Trigger CHOP – especially as I’m going to watch a Button for a signal change. That said, the Trigger CHOP might be handy if I’m watching something that doesn’t have a specific binary, or a signal where I want a certain threshold to act as the trigger. You’ll notice that my Trigger is bypassed, but I’ve left it in my network just in case I want to use a different kind of triggering method. Alright, with some of those things in mind, lets move back to the beginning of this string.
First off I start by adding to Button COMPs to my network (If you want to learn more about Buttons and Control Panels Start here). Zooming into the button COMP I can set the text for the button itself. First I want to find the Text TOP labeled “bg.” Then I want to open the parameter window for this TOP and change the Text to “Forward” (you can name this whatever you want, I just wanted to know that this button was going to move me forward through my set of photos).
We’ll do the same thing for the other button, and in my case I both changed it’s name and it’s color. You can do both from the Text TOP in your second Button COMP.
Moving back out of the Button COMP I’m going to make a few other changes to my buttons. I want to change their position on the control panel, and I want to make them a little larger to accommodate the longer words inside of them. To do this I’m going to open up the parameter window of the Button COMPs and change the width of both to 66. I’m also going to change the Y location of button labeled “Forward” to 55 to make sure that my buttons aren’t on top of one another.
Before moving on, I also want to change the button Type for both of these COMPs to “Momentary.”
Next I’m going to connect my Button called “forward” to the top inlet on my Count CHOP, and the Button “reset” to the middle inlet on the Count CHOP. This means that every time I click the forward button I’ll increment the count up by 1, and when I click reset it will set the counter back to 0.
In my Math CHOP the only change that I’m going to make is to Pre-Add 1 to the integer coming form my count. I’m going to do this because TouchDesigner counts the first row of a table as 0. When we get to our DATs we’ll see that the 0 line in our table is actually the header of a table. While I could tell TouchDesigner not to show the header, that doesn’t feel like the best solution – especially as I want to be able to see what columns are referring to.
Last but not least, I’m going to end this string of CHOPs in a Null. If you’re new to TouchDesigner, it’s important to know that ending a string in a Null can be a true life safer. Ending in a Null allows you to make changes up stream of the Null, without any headache. Let’s imagine in a complicated network that you’ve connected 20 or 50 different operators to a CHOP. You decide that you want to change something in your string, and you delete the final CHOP (the one that’s connected to everything) leaving you to reconnect all of those patch chords in order to get your network back up and running again. The better solution is to end the string in a Null, and then connect the Null to those 20 or 50 or 1000 other operators. Changing things up stream of the Null is easy, especially as you don’t have to reconnect all of your patch chords again.
Now let’s take a look at our DAT stream.
(Text) – Folder – Select – Null
Here the Text DAT isn’t an essential part of my network, at least in terms of operation. As a general rule of thumb, I try to add comments to my networks as I’m working in them in order to make sure that I can remember how I did something. I highly recommend having some kind of commenting system, especially as this can prove to be a helpful tool to communicate with collaborators about what you’re doing with a specific part of a network. All of that to say, that we can ignore my first Text DAT.
The Folder DAT will pull the contents of a specified system folder. Ultimately, I’ll need the pathway of the files in this folder. I can set the Folder DAT to give me all of that information, and specify if I want it to include the content of sub folders, or the names of sub folders. In my case I only want the names and locations of the files in this single folder.
Next I want to select a single line out of this whole table. To do this, we’re going to connect the Folder DAT to a Select DAT.
First up I want to set this DAT to extract Rows by Index. I want to make sure that both Include First Row, and Include First Column is turned off. Next I want to export the Null CHOP to both the Start Row Index and the End Row Index. Finally, I want to set the Start Column Index to 5, and the End Column Index to 5 – I’m telling the Select DAT that I’m only interested in the sixth column in this table (but you set it to 5, whats the deal? remember 0 counts as a column, so when you’re counting columns in your table 0 is the new 1). I’m also telling it that I only want to see the row that’s specified by the CHOP string.
Last but not least, I’m going to pass this to a Null.
Finally, let’s add a Movie-In TOP to our network. Now, in the Movie-In parameter dialog we’re going to do a little typing. We need to tell the Movie-in TOP that it should reference a cell in a table in a DAT. Easy. Right? Sure it is. We’re going to first click the little plus that shows up as your pointer hovers over the left side of the parameter window.
Next we’re going to toggle the field from a constant into a expression by clicking on the little blue box.
Finally, we’re going to write a short expression to tell TouchDesigner where to look for the pathway of a file to load. Our expression looks like this:
op(‘null1’)[0,0]
If we were writing that in English it would read – Look at the Operator named “null1” and find the contents of the cell in the 0 column position and in the 0 row position. It’s important to note that the name in single quotes should be the name of the DAT Null that we created before, otherwise this won’t act as expected.
There you have it. We’ve now made a network that will allow us to load the contents of a folder, sequentially based on how we use two buttons in our control panel.
Matthew Ragan 