diff --git a/demo2.cpp b/demo2.cpp
index afbf7e1..5af058b 100644
--- a/demo2.cpp
+++ b/demo2.cpp
@@ -1,8 +1,11 @@
 /**
   Raycasting demo 2 for Pokitto.
 
-  This demo shows the simple version (only 1 intersection) of raycasting. Has
-  a fairly high FPS.
+  This demo shows a simple version (wolf3D-like) raycasting. It has a fairly
+  high FPS.
+
+  There is a number of compile-time settings you can try! Look at the defines
+  below.
 
   Don't forget to compile with -O3!
 
@@ -10,6 +13,31 @@
   license: CC0 1.0
 */
 
+// settings:
+
+//#define SUBSAMPLE 1
+  /* ^ Turns high resolution in X direction on, which means twice as many rays
+       that will be cast. The result looks beautiful but dramatically decreases
+       FPS. */
+
+//#define RENDER_PRECISE
+  /* ^ Turns on rendering using a more precise but slower algorithm. This can
+       be seen at less shaky head bobbing when moving. */
+
+//#define NO_TEXTURES
+  /* ^ Turns off textures and only uses colors, which increases FPS. */
+
+//#define USE_DIST_APPROX 1 
+  /* ^ Turns on distance approximation, which won't compute exact distances but
+       only approximations - this should increase performance a little, but
+       results in slightly distorted walls. */
+
+//#define USE_COS_LUT 2
+  /* ^ Turns on cos look up tables (128 items, USE_COS_LUT 1 will use only 64
+       items), which should theoretically be faster, but will take additional
+       memory and turning can be less precise (can be seen a lot with 64 item
+       LUT). */
+
 #define FPS 60
 #define HEAD_BOB_HEIGHT 200
 #define HEAD_BOB_STEP 20
@@ -781,9 +809,13 @@ inline void pixelFunc(PixelInfo *pixel)
   {
     Unit textureScroll = pixel->hit.type != 4 ? 0 : 16 * pokitto.frameCount;
 
+#ifdef NO_TEXTURES
+    c = textureAverageColors[pixel->hit.type];
+#else
     c = pixel->depth < TEXTURE_MAX_DISTANCE ?
       sampleImage(textures[pixel->hit.type],pixel->hit.textureCoord + textureScroll,pixel->textureCoordY) :
       textureAverageColors[pixel->hit.type];
+#endif
 
     if (previousColumn == pixel->position.x)
     {
@@ -810,11 +842,12 @@ void draw()
   c.computeTextureCoords = 1;
 
   player.mCamera.height += player.mHeadBob;
-  renderSimple(player.mCamera,floorHeightAt,textureAt,pixelFunc,c);
 
-  /* this would achieve more or less the same (less shaky head bob), 
-     for a cost of a few FPS: */
-  // render(player.mCamera,floorHeightAt,0,textureAt,pixelFunc,c);
+#ifdef RENDER_PRECISE
+  render(player.mCamera,floorHeightAt,0,textureAt,pixelFunc,c);
+#else
+  renderSimple(player.mCamera,floorHeightAt,textureAt,pixelFunc,c);
+#endif
 
   player.mCamera.height -= player.mHeadBob;