diff --git a/demo1.cpp b/demo1.cpp
index ec6a58b..e9d16ea 100644
--- a/demo1.cpp
+++ b/demo1.cpp
@@ -11,6 +11,7 @@
 */
 
 // redefine some parameters
+#define FPS 40
 #define GRAVITY_ACCELERATION (UNITS_PER_SQUARE * 3)
 #define PLAYER_JUMP_SPEED 700
 #define CAMERA_COLL_HEIGHT_BELOW ((3 * UNITS_PER_SQUARE) / 2)
@@ -695,14 +696,14 @@ Unit ceilingHeightAt(int16_t x, int16_t y)
   Function for drawing a single pixel (like fragment shader). Bottleneck =>
   should be as fast as possible.
 */
-inline void pixelFunc(PixelInfo pixel)
+inline void pixelFunc(PixelInfo *pixel)
 {
-  if (pixel.position.y == MIDDLE_ROW)
-    zBuffer[pixel.position.x] = pixel.depth;
+  if (pixel->position.y == MIDDLE_ROW)
+    zBuffer[pixel->position.x] = pixel->depth;
 
   uint8_t c;
 
-  Unit depth = pixel.depth - UNITS_PER_SQUARE * 3;
+  Unit depth = pixel->depth - UNITS_PER_SQUARE * 3;
   depth = depth > 0 ? depth : 1;
 
   int intensity = 7 - (depth * 7) / (UNITS_PER_SQUARE * 5);
@@ -710,26 +711,26 @@ inline void pixelFunc(PixelInfo pixel)
   if (intensity < 0)
     intensity = 0;
 
-  if (pixel.isWall)
+  if (pixel->isWall)
   {
-    if ((pixel.hit.direction == 0 || pixel.hit.direction == 2))
+    if ((pixel->hit.direction == 0 || pixel->hit.direction == 2))
       intensity -= 2;
 
     if (intensity < 0)
       intensity = 0;
 
-    c = sampleImage(textures[pixel.hit.type],pixel.hit.textureCoord,pixel.textureCoordY);
+    c = sampleImage(textures[pixel->hit.type],pixel->hit.textureCoord,pixel->textureCoordY);
     c = addIntensity(c,intensity - 3);
   }
   else
-    c = pixel.isFloor ?
+    c = pixel->isFloor ?
           rgbToIndex(intensity/2,intensity,intensity/3) :
           rgbToIndex(intensity,intensity/2,0);
 
   uint8_t *buf = pokitto.display.screenbuffer;
 
-  buf += pixel.position.x * SUBSAMPLE;
-  buf += pixel.position.y * SCREEN_WIDTH;
+  buf += pixel->position.x * SUBSAMPLE;
+  buf += pixel->position.y * SCREEN_WIDTH;
 
   #pragma unroll
   for (uint8_t i = 0; i < SUBSAMPLE - 1; ++i)
@@ -784,9 +785,8 @@ int main()
 {
   initGeneral();
 
-//  player.setPositionSquare(4,5);
-player.setPositionSquare(6,4);
-player.mCamera.direction = 256;
+  player.setPositionSquare(6,4);
+  player.mCamera.direction = 256;
 
   sprites[0] = Sprite(sprite1,10,5,1,100);
   sprites[1] = Sprite(sprite1,14,5,1,100);
diff --git a/demo2.cpp b/demo2.cpp
index 4bb93cf..1cb6573 100644
--- a/demo2.cpp
+++ b/demo2.cpp
@@ -766,42 +766,42 @@ int8_t pixelIntensity = 0; ///< Precomputed column intensity addition.
 /**
   Function for drawing a single pixel (like fragment shader).
 */
-inline void pixelFunc(PixelInfo pixel)
+inline void pixelFunc(PixelInfo *pixel)
 {
-  if (pixel.position.y == MIDDLE_ROW)
-    zBuffer[pixel.position.x] = pixel.depth;
+  if (pixel->position.y == MIDDLE_ROW)
+    zBuffer[pixel->position.x] = pixel->depth;
 
   uint8_t c = 0;
 
-  if (!pixel.isWall)
+  if (!pixel->isWall)
   {
-    c = pixel.isFloor ? cFloor: cCeiling;
+    c = pixel->isFloor ? cFloor: cCeiling;
   }
   else
   {
-    Unit textureScroll = pixel.hit.type != 4 ? 0 : 16 * pokitto.frameCount;
+    Unit textureScroll = pixel->hit.type != 4 ? 0 : 16 * pokitto.frameCount;
 
-    c = pixel.depth < TEXTURE_MAX_DISTANCE ?
-      sampleImage(textures[pixel.hit.type],pixel.hit.textureCoord + textureScroll,pixel.textureCoordY) :
-      textureAverageColors[pixel.hit.type];
+    c = pixel->depth < TEXTURE_MAX_DISTANCE ?
+      sampleImage(textures[pixel->hit.type],pixel->hit.textureCoord + textureScroll,pixel->textureCoordY) :
+      textureAverageColors[pixel->hit.type];
 
-    if (previousColumn == pixel.position.x)
+    if (previousColumn == pixel->position.x)
     {
       c = addIntensity(c,pixelIntensity);
     }
     else
     {
       // optimization: precompute intensity for the whole column
-      pixelIntensity = 1 - pixel.depth / (UNITS_PER_SQUARE * 2) + (pixel.hit.direction % 2 == 0 ? 2 : 0);
-      previousColumn = pixel.position.x;
+      pixelIntensity = 1 - pixel->depth / (UNITS_PER_SQUARE * 2) + (pixel->hit.direction % 2 == 0 ? 2 : 0);
+      previousColumn = pixel->position.x;
       c = addIntensity(c,pixelIntensity);
     }
   }
 
   uint8_t *buf = pokitto.display.screenbuffer;
 
-  buf += pixel.position.x * SUBSAMPLE;
-  buf += pixel.position.y * pokitto.display.width;
+  buf += pixel->position.x * SUBSAMPLE;
+  buf += pixel->position.y * pokitto.display.width;
 
   #pragma unroll
   for (uint8_t i = 0; i < SUBSAMPLE - 1; ++i)
diff --git a/demo3.cpp b/demo3.cpp
index 3af0e04..ae304a9 100644
--- a/demo3.cpp
+++ b/demo3.cpp
@@ -194,36 +194,36 @@ uint16_t backgroundColumn = 0; ///< Precomputed background column.
 /**
   Function for drawing a single pixel (like fragment shader).
 */
-inline void pixelFunc(PixelInfo pixel)
+inline void pixelFunc(PixelInfo *pixel)
 {
   uint8_t c = 0;
   int16_t intensity = 0;
 
-  if (pixel.isWall)
+  if (pixel->isWall)
   {
-    c = pixel.hit.square.x != selectedSquare.x || pixel.hit.square.y != selectedSquare.y || (editing && pokitto.frameCount % 2) == 0 ?
-        squareColors[pixel.hit.type] : 30;
+    c = pixel->hit.square.x != selectedSquare.x || pixel->hit.square.y != selectedSquare.y || (editing && pokitto.frameCount % 2) == 0 ?
+        squareColors[pixel->hit.type] : 30;
     
-    intensity = pixel.depth / (UNITS_PER_SQUARE * 3);
-    intensity += pixel.hit.direction % 2 == 0 ? 2 : 0;
+    intensity = pixel->depth / (UNITS_PER_SQUARE * 3);
+    intensity += pixel->hit.direction % 2 == 0 ? 2 : 0;
   }
-  else if (pixel.isFloor)
+  else if (pixel->isFloor)
   {
     c = floorColor;
 
-    if (!pixel.isHorizon)
-      intensity = pixel.depth / (UNITS_PER_SQUARE * 3);
+    if (!pixel->isHorizon)
+      intensity = pixel->depth / (UNITS_PER_SQUARE * 3);
   }
   else
   {
-    if (previousColumn == pixel.position.x)
+    if (previousColumn == pixel->position.x)
     {
-      c = imageBackground[2 + backgroundColumn * 22 + min(pixel.position.y,43) / 2];
+      c = imageBackground[2 + backgroundColumn * 22 + min(pixel->position.y,43) / 2];
     }
     else
     {
-      backgroundColumn = absVal(pixel.position.x / 2 + (110 * player.mCamera.direction) / UNITS_PER_SQUARE) % 55;
-      previousColumn = pixel.position.x;
+      backgroundColumn = absVal(pixel->position.x / 2 + (110 * player.mCamera.direction) / UNITS_PER_SQUARE) % 55;
+      previousColumn = pixel->position.x;
     }
   }
 
@@ -232,8 +232,8 @@ inline void pixelFunc(PixelInfo pixel)
 
   uint8_t *buf = pokitto.display.screenbuffer;
 
-  buf += pixel.position.x * SUBSAMPLE;
-  buf += pixel.position.y * SCREEN_WIDTH;
+  buf += pixel->position.x * SUBSAMPLE;
+  buf += pixel->position.y * SCREEN_WIDTH;
 
   #pragma unroll
   for (uint8_t i = 0; i < SUBSAMPLE - 1; ++i)
@@ -291,7 +291,6 @@ void cameraFlyBy(uint32_t dt)
 
   player.mCamera.position.x += step * 30;
   player.mCamera.position.y += step * 15;
-
   player.mCamera.direction = sinInt(pokitto.frameCount / 8);
 }