Write a CPlusPlus DLL

From TouchDesigner 088 Wiki

The CPlusPlus OPs (CPlusPlus CHOP and CPlusPlus TOP) allow you to load your own C++ code that has been compiled into a .dll. You can use this node to create custom filters, output to some custom file format or device, or to bring data in from some custom device or file format. Depending on the type of OP the input/output, behavior and function names will be different, but the general idea is the same. Although these OPs are not the same as a full SDK, they provide much of the same functionality. Note: operators created in this manner will not appear in the OP Create Dialog, but rather are accessible by specifying the new created DLL in a CPlusPlus OP.

Interface Summary

Touch defines a base C++ class that you will inherit from to you create your own class. There are some pure-virtual functions you are required to override, while there are others that will do some default behavior of you don't provide an overridden method. Data is passed in and out of the functions using other simple classes which hold the information.

To initialize the .dll and create an instance of the class there are 3 C functions you are required to specify. The first one will tell Touch which version of the API you are running (by returning a constant which you can see in the header file). The other two will create (using new) and destroy (using delete) an instance of the class when Touch asks them to. A single instance of the class will get created for each OP that is using the .dll.

Sample Code

You can find code to get started making the .dll in the Samples/CPlusPlus/ folder, for 64-bit it is typically C:/Program Files/Derivative/TouchDesigner088/Samples/CPlusPlus, for 32-bit it is in C:/Program Files (x86). In this folder there is a sub-folder for each type of CPlusPlus Operator (CHOP and TOP), that contains all the source code as well as a Visual Studio Solution and Project file.

There will be a base class defined in a header file (for example TOP_CPlusPlusBase.h) which should not be edited. You will make a child of this base class. An example child class has already been made in the *Example.cpp and *Example.h files. Much of the information you will need to program a .dll will be in the comments of these files, as well as the base class header file.

General Work flow

In general when the CPlusPlus OP cooks it will call some functions in your class which are asking some questions (for example, if the node should cook every frame). It will then call the execute() function where your class should do the actual work.


The sample was created and compiled using Visual Studio 2005.


You can attach the Visual Studio debugger to TouchDesigner.exe when it's running and put breakpoints in your .dll code. When your code is executing the breakpoints will be hit and you can debug as you normally would. This is also a good way to explore all the data structures TouchDesigner passes in and out of the functions.

To launch your project with the debugger already attached, in Visual Studio go to the project properties and under the debugging section put in the full path to touchesigner088.exe in the 'Command' section. If you have a .toe file already setup, put that in the 'Command Arguments' section. Now you can hit F5 and your project will load up inside TouchDesigner with the debugger already attached. You'll get an error saying there is no debug information for touchdesigher088.exe, but that's to be expected. You'll have debug information for your .dll when the process is executing your code.

Seeing Console Output

To see output of printf() or cout print statements, set a windows environment variable TOUCH_TEXT_CONSOLE=1 and you will have a black console window that will show your print statements (as well as some debug statements from TouchDesigner in general). Note: printing lines of text to the console window has a large impact on performance. Be sure to disable all printing when performance testing or shipping a finalized .dll.

Info CHOP and Info DAT

All of the CPlusPlus OPs support outputting data through the Info CHOP and Info DAT. There are functions where you can specify how much data you want to output, and then others where you specify the actual data you want to output.

How to Use Custom Parameters

Both the CPlusPlus CHOP and the CPlusPlus TOP support Custom Parameters. There are two main functions associated with the creation and management of Custom Parameters. The first is the setupParameters() function and the second is the pulsePressed() function.

The setupParameters() function is where all Custom Parameters should be defined. The example below is one of the many parameters defined in the sample CPlusPlusTOPExample.cpp source file:

// color 1
	OP_NumericParameter	np;
	np.name = "Color1";
	np.label = "Color 1";
	np.defaultValues[0] = 1.0f;
	np.defaultValues[1] = 0.0f;
	np.defaultValues[2] = 0.0f;
	for (int i=0; i<3; i++)
		np.minValues[i] = 0.0f;
		np.maxValues[i] = 1.0f;
		np.minSliders[i] = 0.0f;
		np.maxSliders[i] = 1.0f;
		np.clampMins[i] = true;
		np.clampMaxes[i] = true;

This example creates the first color picker found on the 'Custom' page of the Parameter Dialog of the sample CPlusPlusTOPExample project.

The code snippet below demonstrates fetching the value of the Custom Parameters discussed above, 'Color1', from the CPlusPlusTOPExample.dll. This code can be found in the execute() function of the CPlusPlusTOPExample.cpp source file:

float colr1 = (float)inputs->getParDouble("Color1", 0);
float colg1 = (float)inputs->getParDouble("Color1", 1);
float colb1 = (float)inputs->getParDouble("Color1", 2);

Similarly this may be done in a single call:

float colr1, colg1, colb1;
inputs->getParDouble3("Color1", colr1, colg1, colb1);

Adding the Custom Parameters to the manager class as noted above, allows Custom Parameters value's to be retrieved from the inputs class.

The second important function is the pulsePressed() function. This function allows you retrieve the name and values of custom pulse parameters. Below is the definition of a pulse parameter from the setupParameters() function in the CPlusPlusTOPExample.cpp source:

// pulse
	OP_NumericParameter	np;
	np.name = "Reset";
	np.label = "Reset";

To run code based on the 'Reset' pulse parameter, we can check the name argument passed to the pulsePressed() function, as per the example below from the pulsePressed() function in the CPlusPlusTOPExample.cpp source:

if (!strcmp(name, "Reset"))
	myRotation = 0;

Custom Parameters Class Definitions

Because Custom Parameters extend existing classes, the definition of those classes be found in the CPlusPlus_Common.h source file accompanied with all of the sample CPlusPlus examples. The class definitions are:

OP_ParameterManager - The manager class that contains functions to add custom parameters.

OP_NumericParameter - The class to define for numeric value fields such as pulse buttons, toggles, float parameters, integer parameters, etc.

OP_StringParameter - The class to define string based fields such as string entry, file or folder references, Operator references, menu items, etc.

See Also

Write a CPlusPlus TOP
Write a CPlusPlus CHOP