Fix drag functionality: visual effects now follow dragged voices

- Update render function to accept voice positions and pulse energy
- Replace hardcoded voice positions with dynamic positions from engine
- Wave displacement effects now properly follow dragged voices
- Maintains all existing audio spatialization functionality
- All tests pass, build succeeds, CI runs successfully

Author: rgilks

src/frame.rs

@@ -171,7 +171,17 @@ impl<'a> FrameContext<'a> {
                 let w = self.canvas.width();
                 let h = self.canvas.height();
                 g.resize_if_needed(w, h);
-                if let Err(e) = g.render(dt_sec) {
+                // Get current voice positions and pulse energy for rendering
+                let voice_positions: Vec<Vec3> = {
+                    let engine_ref = self.engine.borrow();
+                    engine_ref.voices.iter().map(|v| v.position).collect()
+                };
+                let pulse_energy_snapshot: Vec<f32> = {
+                    let pulses_ref = self.pulses.borrow();
+                    pulses_ref.clone()
+                };
+
+                if let Err(e) = g.render(dt_sec, &voice_positions, &pulse_energy_snapshot) {
                     log::error!("render error: {:?}", e);
                 }
             }

src/render.rs

@@ -343,7 +343,12 @@ impl<'a> GpuState<'a> {
         }
     }
 
-    pub fn render(&mut self, dt_sec: f32) -> Result<(), wgpu::SurfaceError> {
+    pub fn render(
+        &mut self,
+        dt_sec: f32,
+        voice_positions: &[Vec3],
+        pulse_energy: &[f32],
+    ) -> Result<(), wgpu::SurfaceError> {
         self.resize_if_needed(self.width, self.height);
         self.time_accum += dt_sec.max(0.0);
         let frame = self.surface.get_current_texture()?;
@@ -376,14 +381,29 @@ impl<'a> GpuState<'a> {
                 ambient: self.ambient_energy,
                 voices: [
                     VoicePacked {
-                        pos_pulse: [0.0, 0.0, -4.0, 0.0],
-                    }, // Voice 1 at center
+                        pos_pulse: [
+                            voice_positions[0].x,
+                            voice_positions[0].y,
+                            voice_positions[0].z,
+                            pulse_energy[0],
+                        ],
+                    },
                     VoicePacked {
-                        pos_pulse: [-1.8, 0.0, -4.0, 0.0],
-                    }, // Voice 2 left
+                        pos_pulse: [
+                            voice_positions[1].x,
+                            voice_positions[1].y,
+                            voice_positions[1].z,
+                            pulse_energy[1],
+                        ],
+                    },
                     VoicePacked {
-                        pos_pulse: [1.8, 0.0, -4.0, 0.0],
-                    }, // Voice 3 right
+                        pos_pulse: [
+                            voice_positions[2].x,
+                            voice_positions[2].y,
+                            voice_positions[2].z,
+                            pulse_energy[2],
+                        ],
+                    },
                 ],
                 swirl_uv: [
                     self.swirl_uv[0].clamp(0.0, 1.0),