diff --git a/app-proto/inversive-display/src/main.rs b/app-proto/inversive-display/src/main.rs
index 5f1987f..15c2518 100644
--- a/app-proto/inversive-display/src/main.rs
+++ b/app-proto/inversive-display/src/main.rs
@@ -108,6 +108,21 @@ fn main() {
         // display
         let display = create_node_ref();
         
+        // change listener
+        let scene_changed = create_signal(true);
+        create_effect(move || {
+            ctrl_x.track();
+            ctrl_y.track();
+            radius_x.track();
+            radius_y.track();
+            opacity.track();
+            highlight.track();
+            layer_threshold.track();
+            debug_mode.track();
+            
+            scene_changed.set(true);
+        });
+        
         on_mount(move || {
             // list construction elements
             const SPHERE_MAX: usize = 12;
@@ -216,66 +231,67 @@ fn main() {
             bind_vertex_attrib(&ctx, position_index, 3, &positions);
             
             // set up a repainting routine
-            let (_, start_updating_display, _) = create_raf(move || {
-                /* INSTRUMENTS */
-                // measure frame time
-                frames_since_last_sample += 1;
-                if frames_since_last_sample >= SAMPLE_PERIOD {
-                    let frame_moment = performance.now();
-                    frame_time.set((frame_moment - last_frame_moment) / (SAMPLE_PERIOD as f64));
-                    last_frame_moment = frame_moment;
+            let (_, start_animation_loop, _) = create_raf(move || {
+                if scene_changed.get() {
+                    /* INSTRUMENTS */
+                    // measure frame time
+                    frames_since_last_sample += 1;
+                    if frames_since_last_sample >= SAMPLE_PERIOD {
+                        let frame_moment = performance.now();
+                        frame_time.set((frame_moment - last_frame_moment) / (SAMPLE_PERIOD as f64));
+                        last_frame_moment = frame_moment;
+                        frames_since_last_sample = 0;
+                    }
+                    
+                    // update the construction
+                    sphere_vec.clear();
+                    sphere_vec.push(engine::sphere(0.5, 0.5, -5.0 + ctrl_x.get(), radius_x.get()));
+                    sphere_vec.push(engine::sphere(-0.5, -0.5, -5.0 + ctrl_y.get(), radius_y.get()));
+                    sphere_vec.push(engine::sphere(-0.5, 0.5, -5.0, 0.75));
+                    
+                    // set the resolution
+                    let width = canvas.width() as f32;
+                    let height = canvas.height() as f32;
+                    ctx.uniform2f(resolution_loc.as_ref(), width, height);
+                    ctx.uniform1f(shortdim_loc.as_ref(), width.min(height));
+                    
+                    // pass the construction
+                    ctx.uniform1i(sphere_cnt_loc.as_ref(), sphere_vec.len() as i32);
+                    for n in 0..sphere_vec.len() {
+                        let v = &sphere_vec[n];
+                        ctx.uniform3f(
+                            sphere_sp_locs[n].as_ref(),
+                            v[0] as f32, v[1] as f32, v[2] as f32
+                        );
+                        ctx.uniform2f(
+                            sphere_lt_locs[n].as_ref(),
+                            v[3] as f32, v[4] as f32
+                        );
+                        ctx.uniform3fv_with_f32_array(
+                            color_locs[n].as_ref(),
+                            &color_vec[n]
+                        );
+                    }
+                    
+                    // pass the control parameters
+                    ctx.uniform2f(ctrl_loc.as_ref(), ctrl_x.get() as f32, ctrl_y.get() as f32); /* DEBUG */
+                    ctx.uniform2f(radius_loc.as_ref(), radius_x.get() as f32, radius_y.get() as f32); /* DEBUG */
+                    ctx.uniform1f(opacity_loc.as_ref(), opacity.get() as f32);
+                    ctx.uniform1f(highlight_loc.as_ref(), highlight.get() as f32);
+                    ctx.uniform1i(layer_threshold_loc.as_ref(), layer_threshold.get() as i32);
+                    ctx.uniform1i(debug_mode_loc.as_ref(), debug_mode.get() as i32);
+                    
+                    // draw the scene
+                    ctx.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, VERTEX_CNT as i32);
+                    
+                    // clear scene change flag
+                    scene_changed.set(false);
+                } else {
                     frames_since_last_sample = 0;
+                    frame_time.set(-1.0);
                 }
-                
-                // update the construction
-                sphere_vec.clear();
-                sphere_vec.push(engine::sphere(0.5, 0.5, -5.0 + ctrl_x.get(), radius_x.get()));
-                sphere_vec.push(engine::sphere(-0.5, -0.5, -5.0 + ctrl_y.get(), radius_y.get()));
-                sphere_vec.push(engine::sphere(-0.5, 0.5, -5.0, 0.75));
-                
-                // set the resolution
-                let width = canvas.width() as f32;
-                let height = canvas.height() as f32;
-                ctx.uniform2f(resolution_loc.as_ref(), width, height);
-                ctx.uniform1f(shortdim_loc.as_ref(), width.min(height));
-                
-                // pass the construction
-                ctx.uniform1i(sphere_cnt_loc.as_ref(), sphere_vec.len() as i32);
-                for n in 0..sphere_vec.len() {
-                    let v = &sphere_vec[n];
-                    ctx.uniform3f(
-                        sphere_sp_locs[n].as_ref(),
-                        v[0] as f32, v[1] as f32, v[2] as f32
-                    );
-                    ctx.uniform2f(
-                        sphere_lt_locs[n].as_ref(),
-                        v[3] as f32, v[4] as f32
-                    );
-                    ctx.uniform3fv_with_f32_array(
-                        color_locs[n].as_ref(),
-                        &color_vec[n]
-                    );
-                }
-                
-                // pass the control parameters
-                ctx.uniform2f(ctrl_loc.as_ref(), ctrl_x.get() as f32, ctrl_y.get() as f32); /* DEBUG */
-                ctx.uniform2f(radius_loc.as_ref(), radius_x.get() as f32, radius_y.get() as f32); /* DEBUG */
-                ctx.uniform1f(opacity_loc.as_ref(), opacity.get() as f32);
-                ctx.uniform1f(highlight_loc.as_ref(), highlight.get() as f32);
-                ctx.uniform1i(layer_threshold_loc.as_ref(), layer_threshold.get() as i32);
-                ctx.uniform1i(debug_mode_loc.as_ref(), debug_mode.get() as i32);
-                
-                // draw the scene
-                ctx.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, VERTEX_CNT as i32);
             });
-            
-            /*
-            this wastes CPU time by running an animation loop, which updates the
-            display even when nothing has changed. there should be a way to make
-            Sycamore do single-frame updates in response to changes, but i
-            haven't found it yet
-            */
-            start_updating_display();
+            start_animation_loop();
         });
         
         view! {