Improve physical geometry, fluid solvers, audio, and profiling

tests/outdoor_audio_tests.cpp

@@ -181,6 +181,26 @@ int main() {
         check(std::isfinite(frame.left) && std::isfinite(frame.right),"catalog listener wiring failed");
     }
 
+    // Source stems reconstruct the mix, and muting leaves diagnostic stems alive.
+    auto stem_config=config();
+    stem_config.dual_exhaust=true; stem_config.valve_contact_enabled=true;
+    OutdoorAudio stems(44100,stem_config), muted(44100,stem_config);
+    for(std::size_t j=0;j<4;++j) muted.set_source_enabled(j,false);
+    for(int i=0;i<12000;++i) {
+        const float x=.01f*std::sin(i*.07f);
+        const auto mix=stems.process(x,x*.4f,-x*.2f,x*.1f);
+        auto sum=stems.tail_frame();
+        for(const auto& source:stems.source_frames()) {
+            sum.left+=source.rendered.left; sum.right+=source.rendered.right;
+        }
+        check(std::abs(sum.left-mix.left)<1e-6f && std::abs(sum.right-mix.right)<1e-6f,
+              "source stems do not reconstruct rendered mix");
+        const auto silent=muted.process(x,x*.4f,-x*.2f,x*.1f);
+        check(silent.left==0 && silent.right==0,"muted sources feed listening mix or reverb");
+        check(muted.source_frames()[0].rendered.left==stems.source_frames()[0].rendered.left,
+              "muting changes diagnostic source history");
+    }
+
     ReedValve reed;
     for (int i = 0; i < 10000; i++)
         reed.step(1.f / 44100, 100);