Hello,
I am not quite familiar with C++ but I was studying the render.cpp example for the ultrasonic sensor with Pure Data, hoping to be able to add two more sensors of the same kind to it.

After noticing that they tend to become noisy when together in PureData, and reading some older posts on this forum of people solving this problem using a render.cpp file together with a Pure Data patch, I am positive that this way might make the reading a bit cleaner (it's not terrible right now but there are outliers quite frequently, some of them are negative numbers).

I'd like to keep it simple and copy-paste the sections of the code that refer to the ultrasonic sensor, adding the additional pins used and naming 2 more variables to receive in pure data (like distance 1, distance2 and distance3). This way is not really elegant, so if anyone have suggestions I'm happy to hear them.

Anyway, approaching this task I stumble upon a series of doubts. The first one is about this section (line 34-50 of the example/PureData/custom-render-ultrasonic-distance-sensor):

#define ULTRASONIC_DISTANCE
#ifdef ULTRASONIC_DISTANCE
#define ULTRASONIC_DISTANCE_DIGITAL_OUT // undefine this to use ANALOG out instead
#include <libraries/PulseIn/PulseIn.h>
PulseIn pulseIn;
unsigned int gPulseTriggerIntervalMs = 60; // how often to send out a trigger.
unsigned int gPulseTriggerIntervalSamples; // Set in setup() based on the above
int gPulseMinLength = 7; //to avoid spurious readings
float gPulseRescale = 58; // taken from the datasheet
#ifdef ULTRASONIC_DISTANCE_DIGITAL_OUT
unsigned int gPulseTrigDigitalOutPin = 0; //channel to be connected to the module's TRIGGER pin - check the pin diagram in the IDE
#else // ULTRASONIC_DISTANCE_DIGITAL_OUT
unsigned int gPulseTrigAnalogOutPin = 0; //channel to be connected to the module's TRIGGER pin
#endif // ULTRASONIC_DISTANCE_DIGITAL_OUT
unsigned int gPulseEchoDigitalInPin = 1; //channel to be connected to the modules's ECHO pin via resistor divider. Check the pin diagram in the IDE
int gPulseTriggerCount = 0;
#endif // ULTRASONIC_DISTANCE

Since I want to add 2 more couples of digital pins, do I have to #define again ULTRASONIC_DISTANCE, so that each of them can define a ULTRASONIC_DISTANCE_DIGITAL_OUT(1, 2 and 3)?

Sorry if the question sounds dumb, I have no easy ways to approach this given my current knowledge of C++.