[SOLVED]empty pointer error

//create main body of water in the center
ENTITY* water = ent_create("map_models\\water.hmp",vector(0,0,0),water_prop);

action water_prop()
{
        Water_shaders
        //create tile water terrains
	VECTOR* temp1,temp2;
        var water_len;
	//get the length of the 32x32 vertex hmp
	vec_for_vertex(temp1, me, 1);
	vec_for_vertex(temp2, me, 32);
	water_len = vec_dist(temp1,temp2);

	//create 8 more terrain to tile
	ENTITY* water1 = ent_create("map_models\\water.hmp",vector(0,water_len,0),Water_shaders);
	ENTITY* water2 = ent_create("map_models\\water.hmp",vector(water_len,0,0),Water_shaders);
	ENTITY* water3 = ent_create("map_models\\water.hmp",vector(0,-water_len,0),Water_shaders);
	ENTITY* water4 = ent_create("map_models\\water.hmp",vector(-water_len,0,0),Water_shaders);
	
	ENTITY* water5 = ent_create("map_models\\water.hmp",vector(water_len,water_len,0),Water_shaders);
	ENTITY* water6 = ent_create("map_models\\water.hmp",vector(-water_len,water_len,0),Water_shaders);
	ENTITY* water7 = ent_create("map_models\\water.hmp",vector(water_len,-water_len,0),Water_shaders);
	ENTITY* water8 = ent_create("map_models\\water.hmp",vector(-water_len,-water_len,0),Water_shaders);
}

VECTOR v;
v.x = 5;
v.y = 2;
v.z = 1;

VECTOR *vp = &v; /* makes vp points to v */
<...>
vec_set(vp, ..);
vec_add(vp, ..);
<...>

VECTOR *vp = malloc(sizeof(VECTOR)); /* Allocates the memory needed for a VECTOR struct where vp will point to */
vec_set(vp, vector(5, 2, 1));

var vi;
void camera_scan()
{
        
	VECTOR tempv,temp;
	while(1)
	{
                
		if(mouse_left) //scan while left mouse if pressed
		{
		   tempv.x = mouse_pos.x;
		   tempv.y = mouse_pos.y;
		   tempv.z = 2000;
		   vec_for_screen(tempv,camera);
		   c_trace(camera.x, tempv, IGNORE_ME);
                   //get vertex coordinate with vec_for_vertex
		   vec_for_vertex(temp,hit.entity,hit.vertex); //if fails to return hit.vertex
	           vi = hit.vertex; //store it for panel
                  //Debugging draw point of contact and nearest vertex then draw a line between.
                  draw_point3d(temp.x,vector(0,0,255),100,300);
	          draw_point3d(vector(hit.x,hit.y,hit.z),vector(0,0,255),100,300);
                  draw_line3d(vector(hit.x,hit.y,hit.z),vector(0,0,255),100);
                 draw_line3d(temp.x,vector(0,0,255),100);
			
		}
		wait(1);
	}
}

USE_POLYGON

SCAN_TEXTURE

var hitvertex_global = 0; // global var holding last hit vertexnr
/*
// not sure if a terrain sets the YOU pointer when hit by c_trace. if not use something like this ( or hit.entity )
// and simply change "YOU" below to "terrainEnt"
ENTITY* terrainEnt;
action myTerrain_WED(){ // apply2 terrain in WED
   terrainEnt = me;
}
*/
action / function whatever(){
        ...
        ...
        hitvertex_global = 0;
	VECTOR _temp;
	_temp.x = mouse_pos.x;
	_temp.y = mouse_pos.y;
	_temp.z = 0;
	vec_set (target, _temp);
	target.z = 10000;
	vec_for_screen (_temp,  camera);
	vec_for_screen (target, camera);
        trace_mode = IGNORE_ME | IGNORE_PASSABLE;
	c_trace (_temp, target, trace_mode);
        if (HIT_TARGET){                        // sure "hit" pointer was set ( =hit something ) ?
           hitvertex_global = hit.vertex;        
           if (hitvertex_global && you){   // vertex? you?
              VECTOR _p;
              vec_for_vertex (_p, you, hitvertex_global);
              ent_create ("example.mdl", _p, NULL);
           }
         //same as ent_create ("bla.mdl", target, NULL); so theres no need4 vec_for_vertex in my quick example ^^
      }
        
}

c_trace ( ... );
you.health -= 10;

c_trace ( ... );
if (you) you.health -= 10;

var vert; //to store vertex index next to hit position
void camera_scan()
{
	VECTOR tempv,temp;
	while(1)
	{
		if(mouse_left) 
		{
			tempv.x = mouse_pos.x;
			tempv.y = mouse_pos.y;
			tempv.z = 2000;
			vec_for_screen(tempv,camera);
			c_trace(camera.x, tempv, IGNORE_ME | SCAN_TEXTURE);
			
			if(HIT_TARGET) //needed to prevent crashing when not hitting something :P
			{
				
				vert = ent_nextvertex(hit.entity,hit.x);
				vec_for_vertex(temp,hit.entity,vert);
				
				//for debugging, create a point and line from the hit  position to the nearest index
				draw_point3d(temp.x,vector(0,0,255),100,300);
				draw_point3d(vector(hit.x,hit.y,hit.z),vector(0,0,255),100,300);
				draw_line3d(vector(hit.x,hit.y,hit.z),vector(0,0,255),100);
				draw_line3d(temp.x,vector(0,0,255),100);
			}
		}
		wait(1);
	}
}

#define USE_FOR_LOOP

void main(){
	
	fps_max = 60;
	
	level_load("");
	
	BMAP* skinBmp = bmap_createblack(64, 64, 24);
	bmap_fill(skinBmp, COLOR_WHITE, NULL);
	
	
	ENTITY* terrainEnt = ent_createterrain(NULL, nullvector, 6, 6, 24);
	ent_setskin(terrainEnt, skinBmp, 0);
	
	d3d_lines = 3;
	
	vec_set(camera.x, vector(-180, 77, 166));
	vec_set(camera.pan, vector(339, -49, 0));
	
	mouse_mode = 4;
	
	VECTOR tempVec, vertexVec;
	
	var total_vertices = ent_vertices(terrainEnt);
	var hit_vertex = 0;
	
	int i = 0;
	
	while(terrainEnt){
		
		DEBUG_VAR(total_vertices, 10);
		DEBUG_VAR(hit_vertex, 40);
		
		vec_set(tempVec, mouse_dir3d);
		vec_scale(tempVec, 1000);
		vec_add(tempVec, mouse_pos3d);
		
		if(c_trace(mouse_pos3d, tempVec, IGNORE_PASSABLE + SCAN_TEXTURE) > 0){
			
			hit_vertex = hit.vertex;
			
			draw_point3d(hit.x, COLOR_RED, 100, 3);
		}
		
		if(HIT_TARGET && you && ent_type(you) == 4){
			
			#ifdef USE_FOR_LOOP
				
				for(i = 1; i < total_vertices + 1; i++){
					
					vec_for_vertex(vertexVec, terrainEnt, i);
					
					if(vec_dist(vertexVec.x, hit.x) < 10){
						
						CONTACT* contact = ent_getvertex(terrainEnt, NULL, i);
						contact.z += time_step;
						contact.v = NULL;
						ent_setvertex(terrainEnt, contact, i);					
						
						draw_point3d(vertexVec.x, COLOR_GREEN, 100, 5);
					}
				}
				
			#else
				
				CONTACT* contact = ent_getvertex(terrainEnt, NULL, hit_vertex);
				
				draw_point3d(contact.x, COLOR_GREEN, 100, 5);
				
				contact.z += time_step;
				contact.v = NULL;
				ent_setvertex(terrainEnt, contact, hit_vertex);					
				
			#endif
		}
		
		wait(1);
	}
}