LFOs controlling 2.5-dimensional slider leads to unwanted jumps

Audio Plugins
1

Hey there,

I’m working on a plug-in that controls a wfs-system via osc.
Here is an image of the GUI to get an idea:

gui
gui997×595 41.5 KB

I created three LFO (juce::Oscillator) objects to modulate x, y and z dimension.
The LFOs exist inside the pluginProcessor.
In processBlock() i wrote the following…

    if (xLFO->isInitialised())
    {
        xLFOOut = xLFO->processSample(0.0f);
        yLFOOut = yLFO->processSample(0.0f);
        zLFOOut = zLFO->processSample(0.0f);
        xAttachment->setValueAsCompleteGesture(xLFOOut);
        yAttachment->setValueAsCompleteGesture(yLFOOut);
        zAttachment->setValueAsCompleteGesture(zLFOOut);
    }

… to make the oscillators move forwards once per audio-callback.

In my gui class when you hit the lfo start button the following happens:

            LFOStartButton.setButtonText("Stop");
            LFOStartButton.setColour(juce::TextButton::buttonColourId, seamlessGrey);
            audioProcessor.xLFO->setFrequency(xRate);
            audioProcessor.xLFO->initialise([xDepth, xPhase, xRate, xOffset](float x)
                {
                    return xDepth * std::sin(xRate * 2 * M_PI * x + xPhase) + xOffset;
                });
            xAttachment->beginGesture();

            audioProcessor.yLFO->setFrequency(yRate);
            audioProcessor.yLFO->initialise([yDepth, yPhase, yRate, yOffset](float x)
                {
                    return yDepth * std::sin(yRate * 2 * M_PI * x + yPhase) + yOffset;
                });
            yAttachment->beginGesture();

            audioProcessor.zLFO->setFrequency(zRate);
            audioProcessor.zLFO->initialise([zDepth, zPhase, zRate, zOffset](float x)
                {
                    return zDepth * std::sin(zRate * 2 * M_PI * x + zPhase) + zOffset;
                });
            zAttachment->beginGesture();

When you hit the stop button:

            LFOStartButton.setButtonText("Start");
            LFOStartButton.setColour(juce::TextButton::buttonColourId, seamlessBlue);

            xAttachment->endGesture();
            audioProcessor.xLFO->reset();
            audioProcessor.xLFO.reset();
            audioProcessor.xLFO = std::make_unique<juce::dsp::Oscillator<float>>();

            yAttachment->endGesture();
            audioProcessor.yLFO->reset();
            audioProcessor.yLFO.reset();
            audioProcessor.yLFO = std::make_unique<juce::dsp::Oscillator<float>>();

            zAttachment->endGesture();
            audioProcessor.zLFO->reset();
            audioProcessor.zLFO.reset();
            audioProcessor.zLFO = std::make_unique<juce::dsp::Oscillator<float>>();
            audioProcessor.prepareLFOs();

the prepareLFOs() function does the following:

    xLFO->prepare(juce::dsp::ProcessSpec({ getSampleRate() / getBlockSize(), (juce::uint32)getBlockSize(), 1 }));
    yLFO->prepare(juce::dsp::ProcessSpec({ getSampleRate() / getBlockSize(), (juce::uint32)getBlockSize(), 1 }));
    zLFO->prepare(juce::dsp::ProcessSpec({ getSampleRate() / getBlockSize(), (juce::uint32)getBlockSize(), 1 }));

it also gets called in prepareToPlay().

Everything works fine, except that in regular time intervals the slider-knob jumps to a certain point of its oscillation as you can see in the following video:
https://youtu.be/Z6K83W2wv9Y

Where and when it jumps depends on the rate of the oscillation.

Does anybody have an idea where this could come from?

Cheers,
Christian