diff --git a/main.c b/main.c
index 7f48335..c9b3b23 100755
--- a/main.c
+++ b/main.c
@@ -141,6 +141,16 @@ void SFG_init();
 
 #define SFG_HEADBOB_ENABLED (SFG_HEADBOB_SPEED > 0 && SFG_HEADBOB_OFFSET > 0)
 
+#define SFG_CAMERA_SHEAR_STEP_PER_FRAME \
+  ((SFG_GAME_RESOLUTION_Y * SFG_CAMERA_SHEAR_SPEED) / SFG_FPS)
+
+#if SFG_CAMERA_SHEAR_STEP_PER_FRAME == 0
+  #define SFG_CAMERA_SHEAR_STEP_PER_FRAME 1
+#endif
+
+#define SFG_CAMERA_MAX_SHEAR_PIXELS \
+  (SFG_CAMERA_MAX_SHEAR * SFG_GAME_RESOLUTION_Y / 1024)
+
 #define SFG_FONT_SIZE_SMALL \
  (SFG_GAME_RESOLUTION_X / (SFG_FONT_CHARACTER_SIZE * 50))
 
@@ -214,19 +224,28 @@ void SFG_recompurePLayerDirection()
 
   SFG_player.direction = RCL_angleToDirection(SFG_player.camera.direction);
 
-  SFG_player.direction.x = (SFG_player.direction.x * SFG_PLAYER_MOVE_UNITS_PER_FRAME) / RCL_UNITS_PER_SQUARE;
-  SFG_player.direction.y = (SFG_player.direction.y * SFG_PLAYER_MOVE_UNITS_PER_FRAME) / RCL_UNITS_PER_SQUARE;
+  SFG_player.direction.x =
+    (SFG_player.direction.x * SFG_PLAYER_MOVE_UNITS_PER_FRAME)
+    / RCL_UNITS_PER_SQUARE;
+
+  SFG_player.direction.y =
+    (SFG_player.direction.y * SFG_PLAYER_MOVE_UNITS_PER_FRAME)
+    / RCL_UNITS_PER_SQUARE;
 
   SFG_backgroundScroll =
-    ((SFG_player.camera.direction * 8) * SFG_GAME_RESOLUTION_Y) / RCL_UNITS_PER_SQUARE; 
+    ((SFG_player.camera.direction * 8) * SFG_GAME_RESOLUTION_Y)
+    / RCL_UNITS_PER_SQUARE; 
 }
 
 void SFG_initPlayer()
 {
   RCL_initCamera(&SFG_player.camera);
 
-  SFG_player.camera.resolution.x = SFG_GAME_RESOLUTION_X / SFG_RAYCASTING_SUBSAMPLE;
+  SFG_player.camera.resolution.x =
+    SFG_GAME_RESOLUTION_X / SFG_RAYCASTING_SUBSAMPLE;
+
   SFG_player.camera.resolution.y = SFG_GAME_RESOLUTION_Y;
+
   SFG_player.camera.height = RCL_UNITS_PER_SQUARE * 12;
   SFG_player.camera.position.x = RCL_UNITS_PER_SQUARE * 15;
   SFG_player.camera.position.y = RCL_UNITS_PER_SQUARE * 8;
@@ -396,7 +415,7 @@ void SFG_pixelFunc(RCL_PixelInfo *pixel)
   {
 #if SFG_DITHERED_SHADOW
     uint8_t fogShadow = (pixel->depth * 4) / (RCL_UNITS_PER_SQUARE);
-    
+   
     uint8_t fogShadowPart = fogShadow & 0x07;
 
     fogShadow /= 8;
@@ -749,8 +768,31 @@ void SFG_gameStep()
 
   int8_t strafe = 0;
 
+#if SFG_HEADBOB_ENABLED
+  int8_t bobbing = 0;
+#endif
+
+  int8_t shearing = 0;
+
   if (SFG_keyPressed(SFG_KEY_A))
   {
+    if (SFG_keyPressed(SFG_KEY_UP))
+    {
+      SFG_player.camera.shear =
+        RCL_min(SFG_CAMERA_MAX_SHEAR_PIXELS,
+                SFG_player.camera.shear + SFG_CAMERA_SHEAR_STEP_PER_FRAME);
+
+      shearing = 1;
+    }
+    else if (SFG_keyPressed(SFG_KEY_DOWN))
+    {
+      SFG_player.camera.shear =
+        RCL_max(-1 * SFG_CAMERA_MAX_SHEAR_PIXELS,
+                SFG_player.camera.shear - SFG_CAMERA_SHEAR_STEP_PER_FRAME);
+
+      shearing = 1;
+    }
+
     if (SFG_keyPressed(SFG_KEY_LEFT))
       strafe = -1;
     else if (SFG_keyPressed(SFG_KEY_RIGHT))
@@ -771,6 +813,23 @@ void SFG_gameStep()
 
     if (recomputeDirection)
       SFG_recompurePLayerDirection();
+
+    if (SFG_keyPressed(SFG_KEY_UP))
+    {
+      moveOffset.x += SFG_player.direction.x;
+      moveOffset.y += SFG_player.direction.y;
+#if SFG_HEADBOB_ENABLED
+      bobbing = 1;
+#endif
+    }
+    else if (SFG_keyPressed(SFG_KEY_DOWN))
+    {
+      moveOffset.x -= SFG_player.direction.x;
+      moveOffset.y -= SFG_player.direction.y;
+#if SFG_HEADBOB_ENABLED
+      bobbing = 1;
+#endif
+    }
   }
 
   if (SFG_keyPressed(SFG_KEY_STRAFE_LEFT))
@@ -804,25 +863,14 @@ void SFG_gameStep()
     (SFG_player.verticalSpeed - SFG_GRAVITY_SPEED_INCREASE_PER_FRAME);
 #endif
 
-#if SFG_HEADBOB_ENABLED
-  int8_t bobbing = 0;
-#endif
+  if (!shearing && SFG_player.camera.shear != 0)
+  {
+    // gradually shear back to zero
 
-  if (SFG_keyPressed(SFG_KEY_UP))
-  {
-    moveOffset.x += SFG_player.direction.x;
-    moveOffset.y += SFG_player.direction.y;
-#if SFG_HEADBOB_ENABLED
-    bobbing = 1;
-#endif
-  }
-  else if (SFG_keyPressed(SFG_KEY_DOWN))
-  {
-    moveOffset.x -= SFG_player.direction.x;
-    moveOffset.y -= SFG_player.direction.y;
-#if SFG_HEADBOB_ENABLED
-    bobbing = 1;
-#endif
+    SFG_player.camera.shear =
+      (SFG_player.camera.shear > 0) ?
+      RCL_max(0,SFG_player.camera.shear - SFG_CAMERA_SHEAR_STEP_PER_FRAME) :
+      RCL_min(0,SFG_player.camera.shear + SFG_CAMERA_SHEAR_STEP_PER_FRAME);
   }
 
 #if SFG_HEADBOB_ENABLED
diff --git a/raycastlib.h b/raycastlib.h
index f57d8f6..e3239d1 100644
--- a/raycastlib.h
+++ b/raycastlib.h
@@ -26,7 +26,7 @@
 
   author: Miloslav "drummyfish" Ciz
   license: CC0 1.0
-  version: 0.87
+  version: 0.88
 */
 
 #include <stdint.h>
@@ -280,6 +280,10 @@ typedef struct
   very often.
 */ 
 typedef RCL_Unit (*RCL_ArrayFunction)(int16_t x, int16_t y);
+/*
+  TODO: maybe array functions should be replaced by defines of funtion names
+  like with pixelFunc? Could be more efficient than function pointers.
+*/
 
 /**
   Function that renders a single pixel at the display. It is handed an info
@@ -1034,7 +1038,7 @@ RCL_Unit RCL_adjustDistance(RCL_Unit distance, RCL_Camera *camera,
 }
 
 /// Helper for drawing floor or ceiling. Returns the last drawn pixel position.
-static inline int16_t _RCL_drawVertical(
+static inline int16_t _RCL_drawHorizontalColumn(
   RCL_Unit yCurrent,
   RCL_Unit yTo,
   RCL_Unit limit1, // TODO: int16_t?
@@ -1058,13 +1062,19 @@ static inline int16_t _RCL_drawVertical(
 
   int16_t limit = RCL_clamp(yTo,limit1,limit2);
 
+  RCL_Unit depth = 0; /* TODO: this is for clamping depth to 0 so that we don't
+                         have negative depths, but we should do it more
+                         elegantly and efficiently */
+
+  _RCL_UNUSED(depth);
+
   /* for performance reasons have different version of the critical loop
      to be able to branch early */
   #define loop(doDepth,doCoords)\
   {\
     if (doDepth) /*constant condition - compiler should optimize it out*/\
     {\
-      pixelInfo->depth += RCL_absVal(verticalOffset) *\
+      depth = pixelInfo->depth + RCL_absVal(verticalOffset) *\
         RCL_VERTICAL_DEPTH_MULTIPLY;\
       depthIncrement = depthIncrementMultiplier *\
         _RCL_horizontalDepthStep;\
@@ -1080,7 +1090,10 @@ static inline int16_t _RCL_drawVertical(
     {\
       pixelInfo->position.y = i;\
       if (doDepth)  /*constant condition - compiler should optimize it out*/\
-        pixelInfo->depth += depthIncrement;\
+      {\
+        depth += depthIncrement;\
+        pixelInfo->depth = RCL_max(0,depth); /*TODO: optimize */\
+      }\
       if (doCoords) /*constant condition - compiler should optimize it out*/\
       {\
         RCL_Unit d = _RCL_floorPixelDistances[i];\
@@ -1287,7 +1300,7 @@ void _RCL_columnFunctionComplex(RCL_HitResult *hits, uint16_t hitCount, uint16_t
     p.depth = 0;
 #endif
 
-    limit = _RCL_drawVertical(fPosY,fZ1Screen,cPosY + 1,
+    limit = _RCL_drawHorizontalColumn(fPosY,fZ1Screen,cPosY + 1,
      _RCL_camera.resolution.y,fZ1World,-1,RCL_COMPUTE_FLOOR_DEPTH,
      // ^ purposfully allow outside screen bounds
        RCL_COMPUTE_FLOOR_TEXCOORDS && p.height == RCL_FLOOR_TEXCOORDS_HEIGHT,
@@ -1307,7 +1320,7 @@ void _RCL_columnFunctionComplex(RCL_HitResult *hits, uint16_t hitCount, uint16_t
         _RCL_horizontalDepthStep;
 #endif
 
-      limit = _RCL_drawVertical(cPosY,cZ1Screen,
+      limit = _RCL_drawHorizontalColumn(cPosY,cZ1Screen,
         -1,fPosY - 1,cZ1World,1,RCL_COMPUTE_CEILING_DEPTH,0,1,&ray,&p);
       // ^ purposfully allow outside screen bounds here
 
@@ -1472,7 +1485,7 @@ void _RCL_columnFunctionSimple(RCL_HitResult *hits, uint16_t hitCount,
   p.depth = 1;
   p.height = RCL_UNITS_PER_SQUARE;
 
-  y = _RCL_drawVertical(-1,wallStart,-1,_RCL_middleRow,_RCL_camera.height,1,
+  y = _RCL_drawHorizontalColumn(-1,wallStart,-1,_RCL_middleRow,_RCL_camera.height,1,
     RCL_COMPUTE_CEILING_DEPTH,0,1,&ray,&p);
 
   // draw wall
@@ -1503,7 +1516,7 @@ void _RCL_columnFunctionSimple(RCL_HitResult *hits, uint16_t hitCount,
   p.depth = (_RCL_camera.resolution.y - y) * _RCL_horizontalDepthStep + 1;
 #endif
 
-  _RCL_drawVertical(y,_RCL_camResYLimit,-1,_RCL_camResYLimit,
+  _RCL_drawHorizontalColumn(y,_RCL_camResYLimit,-1,_RCL_camResYLimit,
     _RCL_camera.height,1,RCL_COMPUTE_FLOOR_DEPTH,RCL_COMPUTE_FLOOR_TEXCOORDS,
     -1,&ray,&p);
 }
@@ -1627,8 +1640,6 @@ RCL_PixelInfo RCL_mapToScreen(RCL_Vector2D worldPosition, RCL_Unit height,
 {
   RCL_PixelInfo result;
 
-  RCL_Unit d = RCL_dist(worldPosition,camera.position);
-
   RCL_Vector2D toPoint;
 
   toPoint.x = worldPosition.x - camera.position.x;
diff --git a/settings.h b/settings.h
index aae71fa..7ff929a 100644
--- a/settings.h
+++ b/settings.h
@@ -108,4 +108,14 @@
 */
 #define SFG_HEADBOB_OFFSET 200
 
+/**
+  Camera shearing (looking up/down) speed, in vertical resolutions per second.
+*/
+#define SFG_CAMERA_SHEAR_SPEED 3
+
+/**
+  Maximum camera shear (vertical angle). 1024 means 1.0 * vertical resolution.
+*/
+#define SFG_CAMERA_MAX_SHEAR 1024
+
 #endif // guard