vk: patch func_wall model/ents visible offsets

Fixes #335

Patching is still done using "model" key, using "_xvk_ent_id" needs
complete overhaul of how patching is done

ref/vk/vk_mapents.c

@@ -334,6 +334,7 @@ static void readFuncWall( const entity_props_t *const props, uint32_t have_field
 	xvk_mapent_func_wall_t *const e = g_map_entities.func_walls + (g_map_entities.func_walls_count++);
 
 	*e = (xvk_mapent_func_wall_t){0};
+
 	e->rendercolor.r = 255;
 	e->rendercolor.g = 255;
 	e->rendercolor.b = 255;
@@ -346,7 +347,6 @@ static void readFuncWall( const entity_props_t *const props, uint32_t have_field
 	if (have_fields & Field_renderfx)
 		e->renderfx = props->renderfx;
 
-
 	if (have_fields & Field_rendermode)
 		e->rendermode = props->rendermode;
 
@@ -355,6 +355,8 @@ static void readFuncWall( const entity_props_t *const props, uint32_t have_field
 		e->rendercolor.g = props->rendercolor[1];
 		e->rendercolor.b = props->rendercolor[2];
 	}
+
+	e->entity_index = g_map_entities.entity_count;
 }
 
 static void addPatchSurface( const entity_props_t *props, uint32_t have_fields ) {

ref/vk/vk_mapents.h

@@ -86,6 +86,7 @@ typedef struct {
 #define MAX_MAPENT_TARGETS 256
 
 typedef struct {
+	int entity_index;
 	string model;
 	int rendermode, renderamt, renderfx;
 	color24 rendercolor;

ref/vk/vk_scene.c

@@ -576,6 +576,16 @@ static void drawEntity( cl_entity_t *ent, int render_mode )
 	{
 		case mod_brush:
 			R_RotateForEntity( model, ent );
+
+			// Patch func_wall offsets
+			// TODO universal entity patching by index O(1); don't loop like that
+			for (int i = 0; i < g_map_entities.func_walls_count; ++i) {
+				xvk_mapent_func_wall_t *const fw = g_map_entities.func_walls + i;
+				if (fw->entity_index == ent->index + 1) {
+					Matrix4x4_ConcatTranslate(model, fw->offset[0], fw->offset[1], fw->offset[2]);
+					break;
+				}
+			}
 			VK_RenderStateSetMatrixModel( model );
 			VK_BrushModelDraw( ent, render_mode, blend, model );
 			break;