feat: add stereo waveform orbit rings

Two perpendicular line-loop rings orbit the sphere, the blue ring
modulated by CH1 and the orange ring by CH2, toggled with key 2.

oscope-sphere/src/OrbitRings.cpp

@@ -0,0 +1,50 @@
+#include "OrbitRings.h"
+#include <cmath>
+
+void OrbitRings::setup(int pointsPerRing) {
+    n_ = pointsPerRing;
+    ring1_.clear();
+    ring2_.clear();
+    ring1_.setMode(OF_PRIMITIVE_LINE_LOOP);
+    ring2_.setMode(OF_PRIMITIVE_LINE_LOOP);
+    for (int i = 0; i < n_; ++i) {
+        ring1_.addVertex(glm::vec3(0.0f));
+        ring2_.addVertex(glm::vec3(0.0f));
+    }
+}
+
+void OrbitRings::setWaveform(const std::vector<float>& ch1,
+                             const std::vector<float>& ch2) {
+    const float twoPi = 6.28318530718f;
+    auto rebuild = [&](ofVboMesh& ring, const std::vector<float>& src,
+                       bool xzPlane) {
+        const int n = static_cast<int>(src.size());
+        for (int i = 0; i < n_; ++i) {
+            const float theta = twoPi * static_cast<float>(i) / n_;
+            float s = 0.0f;
+            if (n > 0) {
+                int idx = static_cast<int>(
+                    static_cast<long long>(i) * n / n_);
+                if (idx >= n) idx = n - 1;
+                s = src[idx];
+            }
+            const float r = baseRadius_ + amp_ * s;
+            const glm::vec3 p = xzPlane
+                ? glm::vec3(r * std::cos(theta), 0.0f, r * std::sin(theta))
+                : glm::vec3(r * std::cos(theta), r * std::sin(theta), 0.0f);
+            ring.setVertex(i, p);
+        }
+    };
+    rebuild(ring1_, ch1, true);
+    rebuild(ring2_, ch2, false);
+}
+
+void OrbitRings::draw() {
+    ofPushStyle();
+    ofSetLineWidth(2.0f);
+    ofSetColor(80, 200, 255);
+    ring1_.draw();
+    ofSetColor(255, 140, 80);
+    ring2_.draw();
+    ofPopStyle();
+}

oscope-sphere/src/OrbitRings.h

@@ -0,0 +1,21 @@
+#pragma once
+#include "ofMain.h"
+#include <vector>
+
+// GL visual unit: two line-loop rings orbiting the sphere in
+// perpendicular planes. Ring 1 follows CH1, ring 2 follows CH2; each
+// point's orbit radius is modulated by the live waveform.
+class OrbitRings {
+public:
+    void setup(int pointsPerRing);
+    void setWaveform(const std::vector<float>& ch1,
+                     const std::vector<float>& ch2);
+    void draw();
+
+private:
+    int       n_          = 0;
+    float     baseRadius_ = 300.0f;
+    float     amp_        = 70.0f;
+    ofVboMesh ring1_;   // CH1, XZ plane
+    ofVboMesh ring2_;   // CH2, XY plane
+};

oscope-sphere/src/ofApp.cpp

@@ -12,6 +12,7 @@ void ofApp::setup() {
     cam_.setFarClip(5000.0f);
 
     sphere_.setup(5, 512, 256, 1024);
+    rings_.setup(512);
 
     hantek_.setSampleRate(16000000u);
     const oscope::HantekStatus st = hantek_.start();
@@ -47,6 +48,7 @@ void ofApp::update() {
     sphere_.pushSpectrogramColumn(analyzerCh1_.magDown(),
                                   analyzerCh2_.magDown());
     sphere_.setWaveform(buf1_, buf2_);
+    rings_.setWaveform(buf1_, buf2_);
 }
 
 void ofApp::draw() {
@@ -54,6 +56,7 @@ void ofApp::draw() {
     ofPushMatrix();
     ofRotateYDeg(ofGetElapsedTimef() * 6.0f);
     if (layerA_) sphere_.drawSkin();
+    if (layerB_) rings_.draw();
     ofPopMatrix();
     cam_.end();
     drawHud();

oscope-sphere/src/ofApp.h

@@ -4,6 +4,7 @@
 #include "AudioAnalyzer.h"
 #include "DemoSignal.h"
 #include "SphereViz.h"
+#include "OrbitRings.h"
 #include <string>
 #include <vector>
 
@@ -23,6 +24,7 @@ private:
     oscope::DemoSignal    demo_{48000.0f};
 
     SphereViz sphere_;
+    OrbitRings rings_;
     ofEasyCam cam_;
 
     std::vector<float> buf1_;