Trill/custom-slider/render.cpp

Defining a custom slider

This example allows you to create a slider from an arbitrary number of pads which can be in any order.

The order of the pads and their pin numbering is defined in slider0Pads etc. We can also set the max number of centroid which will define how many touches can be registered per slider. This is currently set to 3 meaning that 3 individual touch points can be registered per sensor.

Each touch has a location and a touch size which equates to how hard the finger is pushing on the sensor. This example is particularly useful for working with Trill Flex and Trill Craft. When working with these sensors it always important to check that the Prescaler and Noisethreshold settings are optimum for your application. Experiment with different values if you are not getting a reading or seeing lots of cross talk between the sensors.

/*
 ____  _____ _        _
| __ )| ____| |      / \
|  _ \|  _| | |     / _ \
| |_) | |___| |___ / ___ \
|____/|_____|_____/_/   \_\
http://bela.io
*/
 
#include <Bela.h>
#include <cmath>
#include <libraries/Trill/Trill.h>
#include <libraries/Gui/Gui.h>
#include <libraries/Trill/CentroidDetection.h>
 
#define NUM_TOUCH 2 // Number of touches on our custom slider
 
// Gui object declaration
Gui gui;
 
// Trill object declaration
Trill touchSensor;
 
CentroidDetection cd;
// Location of touches on Trill Bar
float gTouchLocation[NUM_TOUCH] = {0.0};
// Size of touches on Trill bar
float gTouchSize[NUM_TOUCH] = {0.0};
// Number of active touches
int gNumActiveTouches = 0;
 
// Sleep time for auxiliary task
unsigned int gTaskSleepTime = 12000; // microseconds
// Time period (in seconds) after which data will be sent to the GUI
float gTimePeriod = 0.015;
 
/*
* Function to be run on an auxiliary task that reads data from the Trill sensor.
* Here, a loop is defined so that the task runs recurrently for as long as the
* audio thread is running.
*/
void loop(void*)
{
        while(!Bela_stopRequested())
        {
                // Read raw pads from Trill sensor
                touchSensor.readI2C();
                cd.process(touchSensor.rawData.data());
                for(unsigned int i = 0; i < cd.getNumTouches() ; i++) {
                        gTouchLocation[i] = cd.touchLocation(i);
                        gTouchSize[i] = cd.touchSize(i);
                }
                gNumActiveTouches = cd.getNumTouches();
                /* you could use compound touch instead
                gTouchLocation[0] = cd.compoundTouchLocation();
                gTouchSize[0] = cd.compoundTouchSize();
                gNumActiveTouches = !(!gTouchSize[0]);
                */
                usleep(gTaskSleepTime);
        }
}
 
bool setup(BelaContext *context, void *userData)
{
 
        // Setup a Trill Craft sensor on i2c bus 1, using the default mode and address
        if(touchSensor.setup(1, Trill::CRAFT)) {
                fprintf(stderr, "Unable to initialise Trill\n");
                return false;
        }
        // set it to DIFF mode: we will only use some pads from it, which we set up next
        touchSensor.setMode(Trill::DIFF);
        // specify which pads to use (and in which order), how many touches and
        // the rescaling divisor for centroid size (depends on the shape and
        // material of your sensing surface)
        cd.setup({0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}, NUM_TOUCH, 3200);
 
        touchSensor.printDetails();
 
        // Set and schedule auxiliary task for reading sensor data from the I2C bus
        Bela_runAuxiliaryTask(loop);
 
        // Setup GUI
        gui.setup(context->projectName);
        return true;
}
 
void render(BelaContext *context, void *userData)
{
        static unsigned int count = 0;
        for(unsigned int n = 0; n < context->audioFrames; n++) {
                // Send number of touches, touch location and size to the GUI
                // after some time has elapsed.
                if(count >= gTimePeriod*context->audioSampleRate)
                {
                        gui.sendBuffer(0, gNumActiveTouches);
                        gui.sendBuffer(1, gTouchLocation);
                        gui.sendBuffer(2, gTouchSize);
 
                        count = 0;
                }
                count++;
        }
}
 
void cleanup(BelaContext *context, void *userData)
{}