Clarify OT order vs drawing order

hello_tile.c

@@ -71,7 +71,10 @@ void display(void)
     
     SetDispMask(1);
     
+    // We're using a reverse OT, so we want to display the last item first. See PsyQ's LibRef47.pdf, p.277
     DrawOTag(ot[db] + OTLEN - 1);
+    // Uncomment the following line to use a regular oredered OT. Uncomment l.100 accordingly
+    //~ DrawOTag(ot[db]);
     
     db = !db;
     
@@ -81,39 +84,61 @@ void display(void)
 
 int main(void)
 {
-    
+    // These two tiles are added at the same OT index
     TILE * blue_tile;
     TILE * pink_tile;
+    // This one is added at a different OT index
+    TILE * yellow_tile;
     
     init();
     
     while (1)
     {
-        ClearOTagR(ot[db], OTLEN);                      // Initialize the reversed ordering table. Last element will be drawn first.
+        // Initialize the reversed ordering table. This means the elements at index OTLEN - 1 is drawn first.
+        ClearOTagR(ot[db], OTLEN);
+        // Use regular order OT, uncomment l.77 accordingly
+        //~ ClearOTag(ot[db], OTLEN); 
         
-        blue_tile = (TILE * ) nextpri;		            // blue_tile is a pointer to primbuf content at adress nextpri, that's cast (type converted) to a blue_tile struc.   
+        // yellow_tile is before pink and blue tile in the code, 
-		
+        // and it displays behind because it is added to a different ot index (od[db] + OTLEN - 1)
-		setTile(blue_tile);                              // initialize the blue_tile structure ( fill the length and tag(?) value )
+        // Using a Regular or Reverse OT will have an effect on drawing order. (See lines 77 and 100)
-		setXY0(blue_tile, CENTERX - 16, CENTERY - 32);   // Set X,Y
+    
-		setWH(blue_tile, 32, 64);                        // Set Width, Height
+        yellow_tile = (TILE * ) nextpri;                   // yellow_tile is a pointer to primbuf content at adress nextpri, that's cast (type converted) to a TILE struc.   
-		setRGB0(blue_tile, 60, 180, 255);                // Set color
+        
-		addPrim(ot[db], blue_tile);                      // Add primitive to ordering table
+        setTile(yellow_tile);                              // initialize the TILE structure ( fill the length and tag(?) value )
+        setXY0(yellow_tile, CENTERX - 32 , CENTERY - 48);  // Set X,Y
+        setWH(yellow_tile, 128, 40);                       // Set Width, Height
+        setRGB0(yellow_tile, 255, 255, 0);                 // Set color
+        addPrim(ot[db] + OTLEN - 1, yellow_tile);                    // Add primitive to ordering table
             
-		nextpri += sizeof(TILE);                    // Increment the adress nextpri points to by the size of TILE struct
+        nextpri += sizeof(TILE);     
+        
+        // blue_tile added at od[db] + OTLEN - 2
+        
+        blue_tile = (TILE * ) nextpri;                  // blue_tile is a pointer to primbuf content at adress nextpri, that's cast (type converted) to a blue_tile struc.   
+        
+        setTile(blue_tile);                              // initialize the blue_tile structure ( fill the length and tag(?) value )
+        setXY0(blue_tile, CENTERX - 16, CENTERY - 32);   // Set X,Y
+        setWH(blue_tile, 32, 64);                        // Set Width, Height
+        setRGB0(blue_tile, 60, 180, 255);                // Set color
+        addPrim(ot[db] + OTLEN - 2, blue_tile);                      // Add primitive to ordering table
+            
+        nextpri += sizeof(TILE);                    // Increment the adress nextpri points to by the size of TILE struct
     
         // pink_tile is after blue_tile in the code, 
-        // but we're using a reversed ordering table
+        // so it is drawn before, thus under blue_tile.
-        // so it is drawn before, thus bellow blue_tile.
+        // However, it is added at the same ot index (od[db] + OTLEN - 2)
+        // so using a Regular or Reverse OT won't have an effect on drawing order.
     
-        pink_tile = (TILE * ) nextpri;		            // pink_tile is a pointer to primbuf content at adress nextpri, that's cast (type converted) to a TILE struc.   
+        pink_tile = (TILE * ) nextpri;                  // pink_tile is a pointer to primbuf content at adress nextpri, that's cast (type converted) to a TILE struc.   
-		
+        
-		setTile(pink_tile);                              // initialize the TILE structure ( fill the length and tag(?) value )
+        setTile(pink_tile);                              // initialize the TILE structure ( fill the length and tag(?) value )
-		setXY0(pink_tile, CENTERX, CENTERY - 64);   // Set X,Y
+        setXY0(pink_tile, CENTERX, CENTERY - 64);   // Set X,Y
-		setWH(pink_tile, 64, 64);                        // Set Width, Height
+        setWH(pink_tile, 64, 64);                        // Set Width, Height
-		setRGB0(pink_tile, 255, 32, 255);                // Set color
+        setRGB0(pink_tile, 255, 32, 255);                // Set color
-		addPrim(ot[db], pink_tile);                      // Add primitive to ordering table
+        addPrim(ot[db] + OTLEN - 2, pink_tile);                      // Add primitive to ordering table
             
-		nextpri += sizeof(TILE);     
+        nextpri += sizeof(TILE);     
     
         FntPrint("Hello tile !");