feat(gui): add GUI components and displays

Source/GUI/FilterDisplay.cpp

@@ -0,0 +1,79 @@
+#include "FilterDisplay.h"
+
+namespace serum
+{
+
+float FilterDisplay::magnitude (float freqHz, float cutoffHz, float res, int type)
+{
+    const float w = (cutoffHz > 1.0f) ? freqHz / cutoffHz : 1.0f;
+    const float q = 0.6f + res * 14.0f;
+    const float w2 = w * w;
+    const float denom = std::sqrt ((1.0f - w2) * (1.0f - w2) + (w / q) * (w / q));
+
+    switch ((FilterModel) type)
+    {
+        case FilterModel::LadderHP: return (denom > 1e-6f) ? w2 / denom : 0.0f;
+        case FilterModel::LadderBP: return (denom > 1e-6f) ? (w / q) / denom : 0.0f;
+        case FilterModel::Screamer: return (denom > 1e-6f) ? (w / (q * 0.7f)) / denom : 0.0f;
+        case FilterModel::Comb:
+            return 0.5f + 0.5f * std::cos (2.0f * juce::MathConstants<float>::pi * freqHz / cutoffHz);
+        case FilterModel::Formant:
+        {
+            float m = 0.0f;
+            const float fc[3] = { cutoffHz * 0.5f, cutoffHz * 1.6f, cutoffHz * 3.2f };
+            for (int i = 0; i < 3; ++i)
+            {
+                const float ww = freqHz / fc[i];
+                const float dd = std::sqrt ((1.0f - ww * ww) * (1.0f - ww * ww) + (ww / q) * (ww / q));
+                m += (ww / q) / (dd + 1e-6f);
+            }
+            return m / 3.0f;
+        }
+        case FilterModel::Diode:
+        default:
+            return (denom > 1e-6f) ? 1.0f / denom : 0.0f;
+    }
+}
+
+void FilterDisplay::setParams (int t, float c, float r, float d, int s)
+{
+    type = t; cutoff = c; res = r; drive = d; slope = s;
+}
+
+void FilterDisplay::paint (juce::Graphics& g)
+{
+    const auto b = getLocalBounds().toFloat();
+    g.setColour (juce::Colours::black.withAlpha (0.4f));
+    g.fillRoundedRectangle (b, 4.0f);
+    g.setColour (theme::outline);
+    g.drawRoundedRectangle (b.reduced (0.5f), 4.0f, 1.0f);
+
+    if (! enabled)
+        return;
+
+    const float cutoffHz = maps::cutoffToHz (cutoff);
+    const int n = 300;
+    juce::Path path;
+    path.startNewSubPath (b.getX() + 4.0f, b.getBottom() - 4.0f);
+
+    for (int i = 0; i <= n; ++i)
+    {
+        const float logF = std::log10 (20.0f) + ((float) i / (float) n) * (std::log10 (20000.0f) - std::log10 (20.0f));
+        const float freq = std::pow (10.0f, logF);
+        const float mag = magnitude (freq, cutoffHz, res, type);
+        const float db = juce::Decibels::gainToDecibels (mag + 1e-5f);
+        const float x = b.getX() + 4.0f + ((float) i / (float) n) * (b.getWidth() - 8.0f);
+        const float y = juce::jmap (db, -30.0f, 12.0f, b.getBottom() - 4.0f, b.getY() + 4.0f);
+        path.lineTo (x, y);
+    }
+
+    path.lineTo (b.getRight() - 4.0f, b.getBottom() - 4.0f);
+    path.closeSubPath();
+
+    g.setColour (theme::accent.withAlpha (0.25f));
+    g.fillPath (path);
+    g.setColour (theme::accent);
+    g.strokePath (path, juce::PathStrokeType (1.5f));
+}
+
+} // namespace serum