diff --git a/Cargo.toml b/Cargo.toml
index 83da5b0..5bb18e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,8 +7,8 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-ansi_term = "0.12"
 bincode = "1.3.1"
+crossterm = "0.18"
 decorum = "0.3"
 dyn-clone = "1.0"
 enum_dispatch = "0.3"
@@ -22,10 +22,11 @@ ndarray = { version = "0.13", features = ["rayon", "serde"] }
 piecewise-linear = "0.1"
 plotly = { version = "0.6", features = ["kaleido", "plotly_ndarray"], path = "../plotly/plotly" }
 serde = "1.0"
-serde_cbor = "0.11"
 structopt = "0.3"
 threadpool = "1.8"
 y4m = "0.7"
+# ansi_term = "0.12"
+# serde_cbor = "0.11"
 
 [dev-dependencies]
 criterion = "0.3"
diff --git a/src/bin/viewer.rs b/src/bin/viewer.rs
index 2daa4a5..92d6a9c 100644
--- a/src/bin/viewer.rs
+++ b/src/bin/viewer.rs
@@ -1,10 +1,12 @@
-use coremem::StaticSim;
+use coremem::{GenericSim as _, StaticSim};
 use coremem::render::{ColorTermRenderer, Renderer as _};
 
 use std::fs::{File, read_dir};
-use std::io::BufReader;
+use std::io::{BufReader, Read as _, stdin};
+use std::ops::Deref;
 use std::path::{Path, PathBuf};
 use structopt::StructOpt;
+use crossterm::event::{Event, KeyCode};
 
 #[derive(Debug, StructOpt)]
 struct Opt {
@@ -16,6 +18,14 @@ struct Frame {
     data: StaticSim,
 }
 
+impl Deref for Frame {
+    type Target = StaticSim;
+    fn deref(&self) -> &Self::Target {
+        &self.data
+    }
+}
+
+#[derive(Default)]
 struct Loader {
     dir: PathBuf,
 }
@@ -51,12 +61,46 @@ impl Loader {
 struct Viewer {
     viewing: Option<Frame>,
     z: u32,
+    loader: Loader,
     renderer: ColorTermRenderer,
 }
 
 impl Viewer {
-    fn switch_frame(&mut self, frame: Frame) {
-        self.viewing = Some(frame);
+    fn prev_frame(&mut self) {
+        println!("<unimplemented>");
+    }
+    fn next_frame(&mut self) {
+        let next_frame = self.loader.load_next(self.viewing.as_ref());
+        if next_frame.is_some() {
+            self.viewing = next_frame;
+            self.render();
+        } else {
+            println!("<end>");
+        }
+    }
+    fn prev_depth(&mut self) {
+        match self.z {
+            0 => {
+                println!("<end>");
+            },
+            _ => {
+                self.z -= 1;
+                self.render();
+            }
+        }
+    }
+    fn next_depth(&mut self) {
+        match self.z {
+            z if z+1 < self.viewing.as_ref().map(|f| f.depth()).unwrap_or(0) => {
+                self.z += 1;
+                self.render();
+            },
+            _ => {
+                println!("<end>");
+            }
+        }
+    }
+    fn render(&self) {
         self.renderer.render_z_slice(self.viewing.as_ref().map(|f| &f.data).unwrap(), self.z, &[]);
     }
 }
@@ -65,6 +109,25 @@ fn main() {
     let opt = Opt::from_args();
     let loader = Loader::new(opt.directory);
     let mut viewer = Viewer::default();
-    let frame = loader.load_next(None);
-    viewer.switch_frame(frame.unwrap());
+    viewer.loader = loader;
+    //let frame = loader.load_next(None);
+    //viewer.switch_frame(frame.unwrap());
+
+    // disable line buffering
+    crossterm::terminal::enable_raw_mode().unwrap();
+    loop {
+        match crossterm::event::read().unwrap() {
+            Event::Key(e) => match e.code {
+                KeyCode::Left => viewer.prev_frame(),
+                KeyCode::Right => viewer.next_frame(),
+                KeyCode::Up => viewer.prev_depth(),
+                KeyCode::Down => viewer.next_depth(),
+                KeyCode::Char('q') => break,
+                _ => {},
+            },
+            _ => {},
+        }
+    }
+    // otherwise terminal is left in a wacky state
+    crossterm::terminal::disable_raw_mode().unwrap();
 }
diff --git a/src/render.rs b/src/render.rs
index f95d496..164cc05 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -1,16 +1,17 @@
-use ansi_term::Color::RGB;
 use crate::geom::{Index, Meters, Vec2, Vec3, Vec3u};
 use crate::{flt::{Flt, Real}, Material as _};
 use crate::mat;
 use crate::sim::{Cell, GenericSim};
 use crate::meas::AbstractMeasurement;
+use crossterm::{cursor, ExecutableCommand as _, QueueableCommand as _};
+use crossterm::style::{style, Color, PrintStyledContent, StyledContent as _};
 use font8x8::{BASIC_FONTS, GREEK_FONTS, UnicodeFonts as _};
 use log::{trace, info};
 use plotly;
 use image::{RgbImage, Rgb};
 use imageproc::{pixelops, drawing};
 use std::fs::File;
-use std::io::BufWriter;
+use std::io::{BufWriter, Write as _};
 use std::path::PathBuf;
 use std::sync::{Mutex, RwLock};
 use y4m;
@@ -274,17 +275,25 @@ pub struct ColorTermRenderer;
 
 impl Renderer for ColorTermRenderer {
     fn render_with_image(&self, _state: &dyn GenericSim, im: &RgbImage) {
-        let square = "█";
-        let buf: String = im
-            .enumerate_rows()
-            .map(|(_y, row)| {
-                format!("{}\n", row.map(|(_x, _y, p)| {
-                    format!("{}", RGB(p.0[0], p.0[1], p.0[2]).paint(square))
-                }).collect::<String>())
-            })
-            .collect();
-
-        println!("{}", buf);
+        // TODO: should scale the image to the size of the terminal!
+        let mut stdout = std::io::stdout();
+        let (w, h) = crossterm::terminal::size().unwrap();
+        stdout.queue(cursor::MoveTo(0, 0));
+        for (y, row) in im.enumerate_rows() {
+            if y >= h.into() {
+                break;
+            }
+            stdout.queue(cursor::MoveDown(1));
+            stdout.queue(cursor::MoveToColumn(0));
+            for (_x, _y, p) in row {
+                stdout.queue(PrintStyledContent(style(" ").on(Color::Rgb {
+                    r: p.0[0],
+                    g: p.0[1],
+                    b: p.0[2],
+                })));
+            }
+        }
+        stdout.flush();
     }
 }