fix: pause sphere auto-rotation while dragging

Auto-rotation ran unconditionally, so it kept spinning during a
camera-orbit drag. Accumulate a frame-rate-independent angle only
when the mouse is not pressed.

oscope-sphere/src/ofApp.cpp

@@ -30,6 +30,10 @@ void ofApp::setup() {
 void ofApp::update() {
     if (frozen_) return;
 
+    // Auto-rotation advances only when the mouse is not orbiting the camera.
+    if (!ofGetMousePressed())
+        spin_ += 6.0f * static_cast<float>(ofGetLastFrameTime());
+
     if (demoMode_) {
         demo_.next(buf1_, buf2_, 8192);
     } else {
@@ -54,7 +58,7 @@ void ofApp::update() {
 void ofApp::draw() {
     cam_.begin();
     ofPushMatrix();
-    ofRotateYDeg(ofGetElapsedTimef() * 6.0f);
+    ofRotateYDeg(spin_);
     if (layerA_) sphere_.drawSkin();
     if (layerC_) sphere_.drawPoints();
     if (layerB_) rings_.draw();

oscope-sphere/src/ofApp.h

@@ -37,5 +37,6 @@ private:
     bool  layerC_   = true;
     int   colormap_ = 0;
     float scopeSr_  = 16.0e6f;
+    float spin_     = 0.0f;
     std::string statusText_;
 };