diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
new file mode 100644
index 00000000..26d1c974
--- /dev/null
+++ b/.devcontainer/Dockerfile
@@ -0,0 +1,2 @@
+FROM debian
+RUN apt-get update && apt-get install -y make g++ libsdl1.2-dev libsdl-ttf2.0-dev libsdl-gfx1.2-dev libsdl-mixer1.2-dev libglew-dev
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 00000000..60603378
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,26 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/docker-existing-dockerfile
+{
+	"name": "Development Container",
+	"build": {
+		// Sets the run context to one level up instead of the .devcontainer folder.
+		"context": "..",
+		// Update the 'dockerFile' property if you aren't using the standard 'Dockerfile' filename.
+		"dockerfile": "Dockerfile"
+	},
+
+	// Features to add to the dev container. More info: https://containers.dev/features.
+	// "features": {},
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Uncomment the next line to run commands after the container is created.
+	// "postCreateCommand": "cat /etc/os-release",
+
+	// Configure tool-specific properties.
+	// "customizations": {}
+
+	// Uncomment to connect as an existing user other than the container default. More info: https://aka.ms/dev-containers-non-root.
+	// "remoteUser": "devcontainer"
+}
diff --git a/.gitignore b/.gitignore
index 321b2a2a..05a6d4a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,7 @@
 .deps/
+/autohdr.h
+/langen
+/makeh
+/language-data.cpp
+/*.o
+/hyperrogue
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 334bba9e..37b03c36 100644
--- a/Makefile
+++ b/Makefile
@@ -51,7 +51,7 @@ endif
 
 
 ifeq (${OS},linux)
-  CXXFLAGS_EARLY += -DLINUX
+  CXXFLAGS_EARLY += -DLINUX -I /usr/include/SDL
   EXE_EXTENSION :=
   LDFLAGS_GL := -lGL
   LDFLAGS_GLEW := -lGLEW
@@ -141,7 +141,7 @@ endif
 ifeq (${HYPERROGUE_USE_ROGUEVIZ},1)
   # Enable RogueViz. RogueViz requires C++17.
   CXXFLAGS_STD = -std=c++17
-  CXXFLAGS_EARLY += -DCAP_ROGUEVIZ=1
+  CXXFLAGS_EARLY += -DCAP_ROGUEVIZ=1 -DCAP_TEXTURE=1
 endif
 
 
diff --git a/config.cpp b/config.cpp
index 727b78b5..c0cef09d 100644
--- a/config.cpp
+++ b/config.cpp
@@ -2816,10 +2816,10 @@ EX void edit_levellines(char c) {
     });
   }
 
-EX geom3::eSpatialEmbedding shown_spatial_embedding() {
+geom3::eSpatialEmbedding shown_spatial_embedding() {
   if(GDIM == 2) return geom3::seNone;
   return geom3::spatial_embedding;
-  }
+}
 
 EX bool in_tpp() { return pmodel == mdDisk && !models::camera_straight; }
 
diff --git a/nonisotropic.cpp b/nonisotropic.cpp
index d39349cb..17de88f8 100644
--- a/nonisotropic.cpp
+++ b/nonisotropic.cpp
@@ -2555,25 +2555,30 @@ EX namespace twist {
   
     M[0][0] = +xx - yy - zz + ww;
     M[1][1] = -xx + yy - zz + ww;
-    M[2][2] = -xx - yy + zz + ww;
-    
-    M[0][1] = -2 * (xy + zw);
-    M[1][0] = -2 * (xy - zw);
-    
-    M[0][2] = 2 * (xz - yw);
-    M[2][0] = 2 * (xz + yw);
-
-    M[1][2] = -2 * (yz + xw);
-    M[2][1] = -2 * (yz - xw);
   
     if(hyperbolic) {
-      swap(M[0][2], M[1][2]);
-      swap(M[2][0], M[2][1]);
-      M[1][2] *= -1;
-      M[2][0] *= -1;
       M[2][2] = xx + yy + zz + ww;
-      return M;
-      }
+    
+      M[0][1] = -2 * (xy + zw);
+      M[1][0] = -2 * (xy - zw);
+      
+      M[0][2] = -2 * (yz + xw);
+      M[2][0] = 2 * (yz - xw);
+
+      M[1][2] = -2 * (xz - yw);
+      M[2][1] = 2 * (xz + yw);
+    } else {
+      M[2][2] = -xx - yy + zz + ww;
+    
+      M[0][1] = -2 * (xy + zw);
+      M[1][0] = -2 * (xy - zw);
+      
+      M[0][2] = 2 * (xz - yw);
+      M[2][0] = 2 * (xz + yw);
+
+      M[1][2] = -2 * (yz + xw);
+      M[2][1] = -2 * (yz - xw);
+    }
 
 
     return M;
diff --git a/rogueviz/dhrg/embedder.cpp b/rogueviz/dhrg/embedder.cpp
index f549aab8..b7c53ebe 100644
--- a/rogueviz/dhrg/embedder.cpp
+++ b/rogueviz/dhrg/embedder.cpp
@@ -192,7 +192,7 @@ void preparegraph() {
     current_logistic.setRT(factor * graph_R, factor * graph_T);
     saved_logistic = current_logistic; 
 
-    // for(int u=0; u<MAXDIST; u++) iprintf("%d/%Ld\n", edgetally[u], tally[u]);
+    // for(int u=0; u<MAXDIST; u++) iprintf("%d/%lld\n", edgetally[u], tally[u]);
 
     fix_logistic_parameters(current_logistic, loglik_logistic, "logistic", 1e-6);
     writestats();
diff --git a/rogueviz/dhrg/loglik.cpp b/rogueviz/dhrg/loglik.cpp
index 1ca4752b..b37ff34c 100644
--- a/rogueviz/dhrg/loglik.cpp
+++ b/rogueviz/dhrg/loglik.cpp
@@ -337,7 +337,7 @@ void build_disttable_approx() {
   for(int k=0; k<threads; k++)
     v.emplace_back([&,k] () {
       auto& dt = results[k];
-      vector<int>  tab(N, N);
+      vector<int> tab(N, N);
       auto p = k ? nullptr : new progressbar(N/threads, "build_disttable_approx");
       for(int i=k; i<N; i+=threads) {
         if(p) (*p)++;
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 00000000..55327749
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,12 @@
+{ pkgs ? import <nixpkgs> {} }:
+  pkgs.mkShell {
+    nativeBuildInputs = with pkgs.buildPackages; [
+      gnumake
+      libgcc
+      haskellPackages.SDL
+      haskellPackages.SDL-ttf
+      haskellPackages.SDL-gfx
+      haskellPackages.SDL-mixer
+      glew
+    ];
+}