diff --git a/app-proto/inversive-display/src/main.rs b/app-proto/inversive-display/src/main.rs
index 15c2518..4da24f5 100644
--- a/app-proto/inversive-display/src/main.rs
+++ b/app-proto/inversive-display/src/main.rs
@@ -9,7 +9,7 @@
 
 extern crate js_sys;
 use core::array;
-use nalgebra::DVector;
+use nalgebra::{DMatrix, DVector};
 use sycamore::{prelude::*, motion::create_raf, rt::{JsCast, JsValue}};
 use web_sys::{console, window, WebGl2RenderingContext, WebGlProgram, WebGlShader, WebGlUniformLocation};
 
@@ -96,14 +96,15 @@ fn main() {
         let radius_y = create_signal(1.0);
         let opacity = create_signal(0.5);
         let highlight = create_signal(0.2);
-        let layer_threshold = create_signal(0.0);
-        let debug_mode = create_signal(false);
+        let turntable = create_signal(false);
+        let layer_threshold = create_signal(0.0); /* DEBUG */
+        let debug_mode = create_signal(false); /* DEBUG */
         
         /* INSTRUMENTS */
         const SAMPLE_PERIOD: i32 = 20;
-        let mut last_frame_moment = 0.0;
+        let mut last_sample_time = 0.0;
         let mut frames_since_last_sample = 0;
-        let frame_time = create_signal(0.0);
+        let mean_frame_interval = create_signal(0.0);
         
         // display
         let display = create_node_ref();
@@ -117,6 +118,7 @@ fn main() {
             radius_y.track();
             opacity.track();
             highlight.track();
+            turntable.track();
             layer_threshold.track();
             debug_mode.track();
             
@@ -133,6 +135,13 @@ fn main() {
                 [0.25_f32, 0.00_f32, 1.00_f32]
             ];
             
+            // timing
+            let mut last_time = 0.0;
+            
+            // scene parameters
+            const TURNTABLE_SPEED: f64 = 0.5;
+            let mut turntable_angle = 0.0;
+            
             /* INSTRUMENTS */
             let performance = window().unwrap().performance().unwrap();
             
@@ -232,22 +241,57 @@ fn main() {
             
             // set up a repainting routine
             let (_, start_animation_loop, _) = create_raf(move || {
+                // get the time step
+                let time = performance.now();
+                let time_step = 0.001*(time - last_time);
+                last_time = time;
+                
+                // move the turntable
+                let turntable_val = turntable.get();
+                if turntable_val {
+                    turntable_angle += TURNTABLE_SPEED * time_step;
+                }
+                
                 if scene_changed.get() {
                     /* INSTRUMENTS */
-                    // measure frame time
+                    // measure mean frame interval
                     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;
+                        mean_frame_interval.set((time - last_sample_time) / (SAMPLE_PERIOD as f64));
+                        last_sample_time = time;
                         frames_since_last_sample = 0;
                     }
                     
+                    // set the orientation and translation
+                    let orientation = {
+                        let ang_cos = turntable_angle.cos();
+                        let ang_sin = turntable_angle.sin();
+                        DMatrix::from_column_slice(5, 5, &[
+                             ang_cos, 0.0, ang_sin, 0.0, 0.0,
+                                 0.0, 1.0,     0.0, 0.0, 0.0,
+                            -ang_sin, 0.0, ang_cos, 0.0, 0.0,
+                                 0.0, 0.0,     0.0, 1.0, 0.0,
+                                 0.0, 0.0,     0.0, 0.0, 1.0
+                        ])
+                    };
+                    let translation = {
+                        const LEN: f64 = -5.0;
+                        const LEN_SQ: f64 = LEN*LEN;
+                        DMatrix::from_column_slice(5, 5, &[
+                            1.0, 0.0,     0.0, 0.0,    0.0,
+                            0.0, 1.0,     0.0, 0.0,    0.0,
+                            0.0, 0.0,     1.0, 0.0,    LEN,
+                            0.0, 0.0, 2.0*LEN, 1.0, LEN_SQ,
+                            0.0, 0.0,     0.0, 0.0,    1.0
+                        ])
+                    };
+                    let construction_to_world = &translation * orientation;
+                    
                     // 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));
+                    sphere_vec.push(&construction_to_world * engine::sphere(0.5, 0.5, ctrl_x.get(), radius_x.get()));
+                    sphere_vec.push(&construction_to_world * engine::sphere(-0.5, -0.5, ctrl_y.get(), radius_y.get()));
+                    sphere_vec.push(&construction_to_world * engine::sphere(-0.5, 0.5, 0.0, 0.75));
                     
                     // set the resolution
                     let width = canvas.width() as f32;
@@ -285,10 +329,10 @@ fn main() {
                     ctx.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, VERTEX_CNT as i32);
                     
                     // clear scene change flag
-                    scene_changed.set(false);
+                    scene_changed.set(turntable_val);
                 } else {
                     frames_since_last_sample = 0;
-                    frame_time.set(-1.0);
+                    mean_frame_interval.set(-1.0);
                 }
             });
             start_animation_loop();
@@ -296,7 +340,7 @@ fn main() {
         
         view! {
             div(id="app") {
-                div { (frame_time.get()) " ms" }
+                div { "Mean frame interval: " (mean_frame_interval.get()) " ms" }
                 canvas(ref=display, width="600", height="600")
                 div(class="control") {
                     label(for="ctrl-x") { "Sphere 0 depth" }
@@ -362,6 +406,14 @@ fn main() {
                         bind:valueAsNumber=highlight
                     )
                 }
+                div(class="control") {
+                    label(for="turntable") { "Turntable" }
+                    input(
+                        type="checkbox",
+                        id="turntable",
+                        bind:checked=turntable
+                    )
+                }
                 div(class="control") {
                     label(for="layer-threshold") { "Layer threshold" }
                     input(