Add invisible wall

TODO.txt

@@ -82,6 +82,9 @@ level ideas:
 - barrel on elevator
 - platforming vertical section in which the player is going upwards out of a big
   hole
+- invisible bridge (perhaps not straight) made of bleckers (invisible walls)
+  over a hole, leading to an easter egg
+- start of level: a corner blocked by an invisible wall, to indicate entrance
 
 bugs:
 

levels.h

@@ -105,6 +105,7 @@ typedef struct
                                      access card. */
 #define SFG_LEVEL_ELEMENT_LOCK1 0x0e
 #define SFG_LEVEL_ELEMENT_LOCK2 0x0f
+#define SFG_LEVEL_ELEMENT_BLOCKER 0x10 ///< Invisible wall.
 
 /* 
   Monsters have lower 4 bits zero and are only distinguished by the 4 upper
@@ -304,7 +305,7 @@ SFG_PROGRAM_MEMORY SFG_Level SFG_levels[SFG_NUMBER_OF_LEVELS] =
       {SFG_LEVEL_ELEMENT_TELEPORT, {20, 40}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
       {SFG_LEVEL_ELEMENT_TERMINAL, {11, 25}},     {SFG_LEVEL_ELEMENT_TERMINAL, {11, 26}},
       {SFG_LEVEL_ELEMENT_MONSTER_WARRIOR, {10, 45}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
-      {SFG_LEVEL_ELEMENT_NONE, {0, 0}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
+      {SFG_LEVEL_ELEMENT_BLOCKER, {14, 26}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
       {SFG_LEVEL_ELEMENT_NONE, {0, 0}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
       {SFG_LEVEL_ELEMENT_NONE, {0, 0}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},
       {SFG_LEVEL_ELEMENT_NONE, {0, 0}},     {SFG_LEVEL_ELEMENT_NONE, {0, 0}},

main.c

@@ -1114,10 +1114,10 @@ RCL_Unit SFG_ceilingHeightAt(int16_t x, int16_t y)
   Gets sprite (image and sprite size) for given item.
 */
 void SFG_getItemSprite(
-  uint8_t elementType, uint8_t *spriteIndex, uint8_t *spriteSize)
+  uint8_t elementType, const uint8_t **sprite, uint8_t *spriteSize)
 {
   *spriteSize = 0;
-  *spriteIndex = elementType - 1;
+  *sprite = (const uint8_t *) &(SFG_itemSprites[elementType - 1]);
 
   switch (elementType)
   {
@@ -1137,7 +1137,12 @@ void SFG_getItemSprite(
     case SFG_LEVEL_ELEMENT_CARD0:
     case SFG_LEVEL_ELEMENT_CARD1:
     case SFG_LEVEL_ELEMENT_CARD2:
-      *spriteIndex = SFG_LEVEL_ELEMENT_CARD0 - 1;
+      *sprite = 
+        (const uint8_t *) &(SFG_itemSprites[SFG_LEVEL_ELEMENT_CARD0 - 1]);
+      break;
+
+    case SFG_LEVEL_ELEMENT_BLOCKER:
+      *sprite = 0;
       break;
 
     default:
@@ -1153,7 +1158,8 @@ uint8_t SFG_itemCollides(uint8_t elementType)
   return 
     elementType == SFG_LEVEL_ELEMENT_BARREL ||
     elementType == SFG_LEVEL_ELEMENT_TREE ||
-    elementType == SFG_LEVEL_ELEMENT_TERMINAL;
+    elementType == SFG_LEVEL_ELEMENT_TERMINAL ||
+    elementType == SFG_LEVEL_ELEMENT_BLOCKER;
 }
 
 void SFG_setAndInitLevel(const SFG_Level *level)
@@ -3649,11 +3655,13 @@ void SFG_draw()
         worldPosition.y =
           SFG_ELEMENT_COORD_TO_RCL_UNITS(e.coords[1]);
 
-        uint8_t spriteIndex;
+        const uint8_t *sprite;
         uint8_t spriteSize;
 
-        SFG_getItemSprite(e.type,&spriteIndex,&spriteSize);
+        SFG_getItemSprite(e.type,&sprite,&spriteSize);
 
+        if (sprite != 0)
+        {
           RCL_PixelInfo p =
             RCL_mapToScreen(
               worldPosition,
@@ -3664,12 +3672,13 @@ void SFG_draw()
           if (p.depth > 0)
           {
             SFG_drawScaledSprite(
-            SFG_itemSprites[spriteIndex],
+              sprite,
               p.position.x * SFG_RAYCASTING_SUBSAMPLE,p.position.y,
               RCL_perspectiveScale(SFG_SPRITE_SIZE(spriteSize),p.depth),
               p.depth / (RCL_UNITS_PER_SQUARE * 2),p.depth - 1000);
           }
         }
+      }
 
     // projectile sprites:
     for (uint8_t i = 0; i < SFG_currentLevel.projectileRecordCount; ++i)