Add map_element_height (finishes sub_662783)

Possibly wrong for some slopes...

src/map.c

@@ -123,34 +123,135 @@ void map_update_tile_pointers()
 }
 
 /**
- * 
+ * Return the absolute height of an element, given its (x,y) coordinates
+ *
  *  rct2: 0x00662783
  * UNFINISHED
  */
-int sub_662783(int x, int y)
+int map_element_height(int x, int y)
 {
 	int i;
 	rct_map_element *mapElement;
 
+	// Off the map
 	if (x >= 8192 || y >= 8192)
 		return 16;
 
-	x &= 0xFFFFFFE0;
-	y &= 0xFFFFFFE0;
+	// Find the tile the element is on
+	int x_tile = x & 0xFFFFFFE0;
+	int y_tile = y & 0xFFFFFFE0;
 
-	i = ((y * 256) + x) / 8;
+	i = ((y_tile * 256) + x_tile) / 32;
 
 	mapElement = TILE_MAP_ELEMENT_POINTER(i);
 	while (mapElement->type & MAP_ELEMENT_TYPE_MASK) {
 		mapElement++;
 	}
 
-	uint32 result =
+	uint32 height =
 		((mapElement->properties.surface.terrain & MAP_ELEMENT_WATER_HEIGHT_MASK) << 20) |
 		(mapElement->base_height << 3);
 
-	uint32 ebx = (mapElement->properties.surface.slope & MAP_ELEMENT_SLOPE_MASK) & ~0x16;
-	// slope logic
+	uint32 slope = (mapElement->properties.surface.slope & MAP_ELEMENT_SLOPE_MASK);
+	uint8 extra_height = (slope & 0x10) >> 4; // 0x10 is the 5th bit - sets slope to double height
+	slope &= 0xF;
 
-	return result;
+	uint8 quad, quad_2; // which quadrant the element is in?
+
+	uint8 xl, yl;
+
+	uint8 TILE_SIZE = 31;
+
+	xl = x & 0x1f;
+	yl = y & 0x1f;
+
+	// slope logic
+	// slope == 0 is flat, and slope == 15 is not used
+
+	// One corner up
+	if ((slope == 1) || (slope == 2) || (slope == 4) || (slope == 8)) {
+	  switch(slope) {
+	  case 1:    // NE corner up
+	    quad = xl + yl - TILE_SIZE;
+	    break;
+	  case 2:    // SE corner up
+	    quad = xl - yl;
+	    break;
+	  case 4:   // SW corner up
+	    quad = TILE_SIZE - yl - xl;
+	    break;
+	  case 8:   // NW corner up
+	    quad = xl - yl;
+	    break;
+	  }
+	  if (quad > 0) {
+	    height += quad / 2;
+	  }
+	}
+
+	// One side up
+	switch(slope) {
+	case 3:   // E side up
+	  height += xl / 2;
+	  break;
+	case 6:   // S side up
+	  height += (TILE_SIZE - yl) / 2;
+	  break;
+	case 9:    // N side up
+	  height += yl / 2;
+	  height++;
+	  break;
+	case 12:  // W side up
+	  height += (TILE_SIZE - xl) / 2;
+	  break;
+	}
+
+	// One corner down
+	if ((slope == 7) || (slope == 11) || (slope == 13) || (slope == 14)) {
+	  switch(slope) {
+	  case 7:   // NW corner down
+	    quad = xl + TILE_SIZE - yl;
+	    quad_2 = xl - yl;
+	    break;
+	  case 11:  // SW corner down
+	    quad = xl + yl;
+	    quad_2 = xl + yl - TILE_SIZE;
+	    break;
+	  case 13:  // SE corner down
+	    quad = TILE_SIZE - xl + yl;
+	    quad_2 = xl - yl;
+	    break;
+	  case 14:  // NE corner down
+	    quad = (TILE_SIZE - xl) + (TILE_SIZE - yl);
+	    quad_2 = TILE_SIZE - yl - xl;
+	    break;
+	  }
+	  height += 0x10;
+	  if (extra_height) {
+	    height += quad / 2;
+	    height++;
+	  }
+	  if (quad_2 < 0) {
+	    height += quad_2 / 2;
+	    height += 0xFF00;
+	  }
+	}
+
+	// Valleys
+	if (slope == 5) { // NW-SE valley
+	  quad = xl + yl;
+	  if (quad > TILE_SIZE + 1) {
+	    quad = TILE_SIZE - xl - yl;
+	    if (quad > 0) {
+	      height += quad / 2;
+	    }
+	  }
+	} else if (slope == 10) { // NE-SW valley
+	  if (xl > yl) {
+	    quad = xl - yl;
+	    height += quad / 2;
+	  }
+	}
+
+	return height;
 }

src/map.h

@@ -184,5 +184,6 @@ enum {
 
 void map_init();
 void map_update_tile_pointers();
+int map_element_height(int x, int y);
 
 #endif

src/news_item.c

@@ -184,17 +184,9 @@ void news_item_get_subject_location(int type, int subject, int *x, int *y, int *
 			*x = SPRITE_LOCATION_NULL;
 			break;
 		}
-		{
-			uint32 eax, ebx, ecx, edx, esi, edi, ebp;
-			eax = (ride->var_050 & 0xFF) * 32 + 16;
-			ecx = (ride->var_050 >> 8) * 32 + 16;
-			RCT2_CALLFUNC_X(0x00662783, &eax, &ebx, &ecx, &edx, &esi, &edi, &ebp);
-			if (edx & 0xFFFF0000)
-				edx >>= 16;
-			*x = eax;
-			*y = ecx;
-			*z = edx;
-		}
+		*x = (ride->var_050 & 0xFF) * 32 + 16;
+		*y = (ride->var_050 >> 8) * 32 + 16;
+		*z = map_element_height(*x, *y);
 		break;
 	case NEWS_ITEM_PEEP_ON_RIDE:
 		peep = &(RCT2_ADDRESS(RCT2_ADDRESS_SPRITE_LIST, rct_sprite)[subject]);
@@ -233,16 +225,10 @@ void news_item_get_subject_location(int type, int subject, int *x, int *y, int *
 		*z = peep->z;
 		break;
 	case NEWS_ITEM_BLANK:
-		{
-			uint32 eax, ebx, ecx, edx, esi, edi, ebp;
-			eax = subject;
-			ecx = subject >> 16;
-			RCT2_CALLFUNC_X(0x00662783, &eax, &ebx, &ecx, &edx, &esi, &edi, &ebp);
-			*x = eax;
-			*y = ecx;
-			*z = edx;
-		}
-		break;
+	   *x = subject;
+	   *y = subject >> 16;
+	   *z = map_element_height(x, y);
+	   break;
 	default:
 		*x = SPRITE_LOCATION_NULL;
 		break;

src/news_item.h

@@ -22,6 +22,7 @@
 #define _NEWS_ITEM_H_
 
 #include "rct2.h"
+#include "map.h"
 
 enum {
 	NEWS_ITEM_NULL,

src/title.c

@@ -152,7 +152,7 @@ static void title_update_showcase()
 {
 	rct_window* w;
 	uint8 script_opcode, script_operand;
-	short x, y;
+	short x, y, z;
 	int i, _edx;
 
 	if (_scriptWaitCounter <= 0) {
@@ -201,18 +201,12 @@ static void title_update_showcase()
 			case TITLE_SCRIPT_LOCATION:
 				x = (*_currentScript++) * 32 + 16;
 				y = (*_currentScript++) * 32 + 16;
-
-				// Set location
-				int eax, ebx, ecx, edx, esi, edi, ebp;
-				eax = x;
-				ecx = y;
-				RCT2_CALLFUNC_X(0x00662783, &eax, &ebx, &ecx, &edx, &esi, &edi, &ebp);
-				_edx = edx;
+				z = map_element_height(x, y);
 
 				// Update viewport
 				w = window_get_main();
 				if (w != NULL) {
-					window_scroll_to_location(w, x, y, _edx);
+					window_scroll_to_location(w, x, y, z);
 					w->flags &= ~0x08;
 					viewport_update_position(w);
 				}