Q: I want my enemies to attack only when they can see the player. How can I calculate something like this ?
A: Here's an enemy that moves in a circle and plays an alarm sound if it can see the player.
SOUND* alarm_wav = "alarm.wav";
action players_code() // attach this action to your player
{
var movement_speed = 20; // movement speed
VECTOR temp, players_sensor;
set (my, INVISIBLE); // 1st person player
player = my; // I'm the player
while (1)
{
my.pan -= 7 * mouse_force.x * time_step;
camera.x = my.x;
camera.y = my.y;
camera.z = my.z + 50 + 1.1 * sin(my.skill44); // play with 50 and 1.1
camera.pan = my.pan;
camera.tilt += 5 * mouse_force.y * time_step;
vec_set (temp.x, my.x); // trace 10,000 quants below the player
temp.z -= 10000;
temp.z = -c_trace (my.x, temp.x, IGNORE_ME | IGNORE_PASSABLE | USE_BOX) - 2; // play with 2
temp.x = movement_speed * (key_w - key_s) * time_step;
temp.y = movement_speed * (key_a - key_d) * 0.6 * time_step;
c_move (my, temp.x, nullvector, IGNORE_PASSABLE | GLIDE);
wait (1);
}
}
action my_enemy() // attach this action to your enemies
{
while (!player) {wait (1);} // wait until the player model is loaded in the level
var alarm_handle, walk_percentage = 0;
while (1)
{
// scans a sector that's got 120 degrees horizontally, 60 degrees vertically and a length of 1000 quants
// the player will be detected only if its action includes this line of code: "player = my;" (without the quotes)
if ((c_scan(my.x, my.pan, vector(120, 60, 1000), IGNORE_ME) > 0) && (you == player))
{
if (!snd_playing(alarm_handle)) // the alarm sound isn't playing already?
{
alarm_handle = snd_play(alarm_wav, 70, 0); // then let's play it!
}
}
c_move (my, vector(5 * time_step, 0, 0), nullvector, IGNORE_PASSABLE | GLIDE);
my.pan += 1 * time_step; // make the enemy rotate in a circle
ent_animate(my, "walk", walk_percentage, ANM_CYCLE); // play the "walk" animation in a loop
walk_percentage += 2 * time_step; // 2 controls the walk animation speed
wait (1);
}
}
Q: I have upgraded to A7.82 but now I'm getting an error with your multiplayer Aum workshops (shooting from the wrong player). How can I fix that?
A: Your hard drive doesn't have enough time to read all the resources; replacing the "wait (-0.5);" instruction from my code with a "wait (-3);" should solve the problem. A more elegant solution is presented below:
my = ent_create ("redsoldier.mdl", vector (100, 50, 40), move_players);
while (my.client_id != dplay_id) wait (1); // wait until the handle is ready
client_ent = handle(my);
Q: I have found the cubemap rendering script at the wiki page. Can someone explain what does it do and how does it work?
A: That script creates a sky cube bitmap by taking 6 screenshots (the 6 faces of a cube) from the level and merging them into a single tga bitmap, just like the one below. You can then use a simple "ent_createlayer" instruction to display your sky cube.
void main()
{
fps_max = 70;
video_mode = 7; // run in 800x600 pixels
video_depth = 32; // 32 bit mode
video_screen = 1; // start in full screen mode
level_load ("mylevel.wmb");
wait (3);
ent_createlayer("skycube+6.tga", SKY | CUBE | VISIBLE , 1);
}
Q: I have tried to add a sound to my fireplace entity, but I can't hear it. I am using this snippet:
var fire_handle;
SOUND* fire = "fire.wav";
ENTITY* fireplace = "fireplace.mdl";
action my_fire()
{
fire_handle = ent_playsound (fireplace, fire, 80);
}
A: Your code has a small problem: it plays the "fire.wav" sound only once and by the time the player moves close to the fireplace, the sound has stopped for good. Use the modified code below:
var fire_handle;
SOUND* fire = "fire.wav";
action my_fire() // attach this action to your fireplace entity
{
fire_handle = ent_playloop(my, fire, 80);
}
Q: I'd like to press a key and have an animated sprite show up, go through all its frames and then disappear. The things should repeat when I press the key again.
A: Here's an example.
function animated_sprite()
{
set(my, BRIGHT);
my.alpha = 100;
my.frame = 1; // start with the first frame
while (my.frame < 20) // change this value if your animated sprite doesn't contain 20 frames
{
my.frame += 1.2 * time_step; // 1.2 gives the animation speed
wait (1);
}
// let's fade out the last animation frame (remove the "while" loop below if you don't want that to happen
while (my.alpha > 0)
{
my.alpha -= 0.7 * time_step; // 0.7 gives the fade-out animation speed
}
ent_remove (my); // remove the sprite
}
function create_sprite()
{
// creates the sprite 300 quants in front of the camera in this example; feel free to use your own values
// use your own animated sprite here
VECTOR sprite_offset;
vec_set (sprite_offset.x, vector(300, 0, 0));
vec_rotate (sprite_offset.x, camera.pan);
vec_add (sprite_offset.x, camera.x);
ent_create("muzzle+20.tga", sprite_offset.x, animated_sprite);
}
function init_startup()
{
on_c = create_sprite; // press the "C" key to create the sprite
}
Q: I want to have certain NPCs track the player and other objects using their heads and eyes. Should I use vertex or bone animations?
A: Use bones - it's much easier to do it. Check out "The Bone Collector" workshop (script23_2.c) that's available at http://tutorial.3dgamestudio.net to see a good example.
Q: I'd like to attach a rotating entity to the player, but it must perform collision detection as it rotates around the player. Can you help?
A: Use the snippet below - it does the job.
ENTITY* dummy_ent;
// the function below moves the "real" rotating entity towards the position of the dummy entity (if possible)
function rotate_guard()
{
proc_mode = PROC_LATE;
while (!dummy_ent) {wait (1);}
VECTOR offset_speed;
while (1)
{
vec_diff(offset_speed.x, dummy_ent.x, my.x);
// normalize the speed with which the "real" entity follows the dummy entity, play with 10
vec_normalize(offset_speed, 10 * time_step);
c_move(my, nullvector, offset_speed.x, IGNORE_PASSABLE | GLIDE);
my.pan = dummy_ent.pan;
wait (1);
}
}
// the function below creates a dummy entity that rotates around the player at all times, penetrating the walls, etc
function rotate_around_player()
{
// set (my, INVISIBLE | PASSABLE); // make the dummy entity invisible and passable
ent_create("guard.mdl", my.x, rotate_guard); // use your own model here
var rotation_angle;
VECTOR my_speed, temp;
while (!player) {wait (1);} // wait until the player model is loaded
my.emask |= (ENABLE_IMPACT | ENABLE_ENTITY);
while (1)
{
my.x = player.x - 250 * cos(rotation_angle);
my.y = player.y - 250 * sin(rotation_angle);
my.z = player.z + 30; // play with 30
rotation_angle += 0.5 * time_step;
vec_set(temp.x, player.x);
vec_sub(temp.x, my.x);
vec_to_angle(my.pan, temp);
wait (1);
}
}
action players_code() // attach this action to your player
{
var movement_speed = 20;
VECTOR temp, players_sensor;
set (my, INVISIBLE);
player = my;
dummy_ent = ent_create("dummy.mdl", nullvector, rotate_around_player); // put this line inside your player action
while (1)
{
my.pan -= 7 * mouse_force.x * time_step;
camera.x = my.x;
camera.y = my.y;
camera.z = my.z + 50 + 1.1 * sin(my.skill44);
camera.pan = my.pan;
camera.tilt += 5 * mouse_force.y * time_step;
vec_set (temp.x, my.x);
temp.z -= 10000;
temp.z = -c_trace (my.x, temp.x, IGNORE_ME | IGNORE_PASSABLE | USE_BOX) - 2;
temp.x = movement_speed * (key_w - key_s) * time_step;
temp.y = movement_speed * (key_a - key_d) * 0.6 * time_step;
c_move (my, temp.x, nullvector, IGNORE_PASSABLE | GLIDE);
wait (1);
}
}
Q: Rarely, the game window goes to the background without any reason; this happens even if my game is running in full screen mode. Why is this happening?
A: Another application takes control; it's usually your antivirus, which doesn't download its updates silently, but pops up a small window that sends your game to the background. Disable the antivirus temporarily and see if this solves the problem; otherwise, you'll have to do the same thing with all the applications that are running in the background until you find the guilty one and you get rid of it / replace it.
Q: I would like to include an NPC script in my rpg level. Can anyone give me an example?
A: Here's an example for an NPC that moves around, stops for a while and then moves again. It can avoid walls and gives some advice if the player comes close to it.
// use a wave file that contains something like "Stay away from the red rabbit, stranger!"
SOUND* advice_wav = "advice.wav";
action my_npc()
{
VECTOR front_pos;
var distance_covered = 0;
var sound_once = 1;
while (!player) {wait (1);} // wait until the player model is loaded
while (1)
{
vec_set(front_pos.x, vector(50, 0, 0)); // compute a position that's placed 50 quants in front of the player
// rotate "front_pos" in the direction (angles) given by the entity
vec_rotate(front_pos.x, my.pan);
vec_add(front_pos.x, my.x); // add the resulting vector to entity's position
// front_pos isn't touching any walls and the player didn't move 500 quants without pausing yet?
if ((c_content(front_pos.x, 0) == 1) && (distance_covered < 500))
{
// 5 gives the movement speed
distance_covered += c_move(my, vector(5 * time_step, 0, 0), nullvector, IGNORE_PASSABLE | GLIDE);
my.skill22 += 5 * time_step; // 5 gives the "walk" animation speed
ent_animate(my, "walk", my.skill22, ANM_CYCLE);
// if the player is closer than 150 quants to the npc and advice_wav wasn't played yet
if ((vec_dist(player.x, my.x) < 150) && (sound_once == 1))
{
sound_once = 2; // don't allow the sound to be played more than once per walking cycle
ent_playsound(my, advice_wav, 50);
}
}
else // the player is close to a wall or it has moved more than 500 quants?
{
sound_once = 1; // reset sound_once
distance_covered = 0; // reset distance_covered!
my.skill99 = 0;
while (my.skill99 < 5) // the npc stays in front of the wall for 5 seconds
{
my.skill99 += time_step / 16;
ent_animate(my, "stand", my.skill22, ANM_CYCLE);
my.skill22 += 3 * time_step; // 3 gives the "stand" animation speed
wait (1);
}
my.skill99 = my.pan;
my.skill99 += random(180); // and then adds a random pan angle to its initial pan, in order to avoid the wall
while (my.pan < my.skill99) // rotate the npc towards the direction given by its new pan angle
{
my.pan += 10 * time_step;
wait (1);
}
}
wait (1);
}
}
Q: I would like to know how can I get the coordinates of a point on an entity's surface that was clicked using the left mouse button.
A: There you go.
VECTOR hit_coords;
BMAP* pointer_tga = "pointer.tga";
function mouse_startup()
{
mouse_mode = 2;
mouse_map = pointer_tga;
while (1)
{
vec_set(mouse_pos, mouse_cursor);
wait(1);
}
}
action players_code() // attach this action to your player
{
var movement_speed = 20;
VECTOR temp, players_sensor;
set (my, INVISIBLE);
player = my;
while (1)
{
my.pan -= 7 * mouse_force.x * time_step;
camera.x = my.x;
camera.y = my.y;
camera.z = my.z + 50 + 1.1 * sin(my.skill44);
camera.pan = my.pan;
camera.tilt += 5 * mouse_force.y * time_step;
vec_set (temp.x, my.x);
temp.z -= 10000;
temp.z = -c_trace (my.x, temp.x, IGNORE_ME | IGNORE_PASSABLE | USE_BOX) - 2;
temp.x = movement_speed * (key_w - key_s) * time_step;
temp.y = movement_speed * (key_a - key_d) * 0.6 * time_step;
c_move (my, temp.x, nullvector, IGNORE_PASSABLE | GLIDE);
wait (1);
}
}
function getcoords_startup()
{
VECTOR pos1, pos2;
while (1)
{
while (!mouse_left) {wait (1);}
while (mouse_left) {wait (1);}
beep();
pos1.x = mouse_pos.x;
pos1.y = mouse_pos.y;
pos1.z = 0;
vec_for_screen (pos1, camera);
pos2.x = mouse_pos.x;
pos2.y = mouse_pos.y;
pos2.z = 20000; // use a big value here
vec_for_screen (pos2, camera);
c_trace (pos1.x, pos2.x, IGNORE_PASSABLE | SCAN_TEXTURE);
// now "hitvertex" holds the coordinates of the closest vertex to the hit point
if (mouse_ent) // the mouse has clicked an entity?
vec_for_vertex(hit_coords, mouse_ent, hitvertex); // then get the xyz coordinates of "hitvertex"
wait (1);
}
}
PANEL* coords_pan = // displays the xyz coordinates of "hitvertex"
{
layer = 15;
digits(50, 20, 6 ,* , 1, hit_coords.x);
digits(50, 40, 6 ,* , 1, hit_coords.y);
digits(50, 60, 6 ,* , 1, hit_coords.z);
flags = SHOW;
}