/ get and set terrain height
function terrain_get_z(ENTITY* ent,number)

// returns the height of the next vertex at the given position
function terrain_height(ENTITY* ent,VECTOR* position)

// return a terrain position above ground
VECTOR* terrain_pos(ENTITY* terrain,x,y,z)

// raise all terrain vertices by the given value
function terrain_raise(ENTITY* terrain, var raise_z)

// raise one terrain vertex by the given value
function terrain_raisevertex(ENTITY* terrain,var x,var y,var raise_z)

function terrain_fence(ENTITY* terrain, var height)

// place an entity at a random position between two height values on terrain
// uses: terrain_buffer
function ent_terrain_place(ENTITY* ent,ENTITY* terrain,minheight,maxheight)

// create entities on terrain, guided from on color spots in a mask
var ent_seed(char* name,ENTITY* terrain,BMAP* mask,COLOR* color,var dist,var mode,EVENT act)

var ent_seed(char* name,ENTITY* terrain,BMAP* mask,COLOR* color,var dist,EVENT act)

action water_block()
{
	while(!me)wait(1);
	
	//this will be the min/max of the water block
	VECTOR water_min;
	VECTOR water_max;
	
	//this should be your player's min/max you dont need this 
	//i did this for the camera as a demo
	VECTOR player_min;
	VECTOR player_max;
	
	while(me)
	{
		//water min/max values plus position
		vec_set(water_min,my.min_x);
		vec_set(water_max,my.max_x);
		
		vec_add(water_min,my.x);
		vec_add(water_max,my.x);
		
		//player min/max 
		//this should be your player sizes you wish to test intersection against
		vec_set(player_min,vector(camera.x-50,camera.y-50,camera.z-50));
		vec_set(player_max,vector(camera.x+50,camera.y+50,camera.z+50));
		
		//check if player min/max , intersects with , water min/max
		if(c_intersect(water_min,water_max,NULL,player_min,player_max,NULL)==-1)
		{
			DEBUG_VAR(1,100);
			draw_box3d(water_min,water_max,COLOR_GREEN,100);
		}
		else 
		{
			DEBUG_VAR(0,100);
			draw_box3d(water_min,water_max,COLOR_RED,100);
		}

		wait(1);

	}
}

function main()
{
   ...

   level_terrain = level_ent; // CAUSING terrain_get_z ERROR WHEN REGION IS  PRESENT.
   terrain_tile(level_terrain); // CAUSING terrain_get_z ERROR WHEN REGION IS PRESENT.

   ...
}