Controlling NPCs with Types

Blitz3D Forums/Blitz3D Tutorials/Controlling NPCs with Types

Drak (Posted 2010) [#1]

I've seen a few posts lately about how to control enemies or NPCs and simple AI. Here's a simple way to control your NPCs using types. All you need to do is have a status or state field in your NPC type. Each frame, act upon the chosen state. It's pretty simple. First: What do we want to do? We want the enemy NPC to sit idle, look for the player.. If they see the player, follow him, and if he gets close enough, attack! Then, we want to return the enemy NPC to it's starting location. When the enemy returns to it's post, it will begin searthing for the player again.... To see the difference in states, we'll change the color of the enemy NPCs so we can visually see what state they are in. If the player gets within say 10 units of the enemy, the enemy will become aggressive. We want the enemy to follow the player either until the player gets too far away or the enemy reaches the player, in which case it will attack the player. That's all we need to know to get started! Here is the commented code: ;Waypoint Example By Drak, 3/8/2010 ;************************************************************ ;THIS PROGRAM WILL: * ;Create a player mesh (a square) * ;Create some enemies (some spheres) * ;Make on-the-fly waypoints for the enemies to return to * ;Return the enemies to the waypoints * ;Also shows some some rudimentary AI * ;Shows some very simple particle effects as well * ;************************************************************ AppTitle "Drak's Waypoint Example" ;------------------------------------------------------------------------------------------------------- ;INITIALIZATION ;------------------------------------------------------------------------------------------------------- Graphics3D 800,600 SetBuffer BackBuffer() SeedRnd MilliSecs() Global player = CreateCube() ;create a cube for the player EntityColor player, 0,0,200 ;we'll make the player blue Global player_hp = 10 ;give the player 10 hit points Global player_alive = 1 ;player is indeed alive Global camera = CreateCamera() ;create a camera PositionEntity camera, 0,40,0 ;raise it up in the air RotateEntity camera, 90,0,0 ;point it down ;------------------------------------------------------------------------------------------------------- ;TYPES ;------------------------------------------------------------------------------------------------------- Type enemy Field mesh ;will hold the actual mesh Field return_waypoint ;will hold the handle of the return waypoint Field status ;holds a # referring to the enemies status Field speed# ;this will hold the speed of the enemy End Type Type particle Field mesh ;holds mesh Field alpha# ;holds alpha Field speed_x# ;speed x Field speed_y# ;same Field speed_z# ;same... Field fade_speed# ;fade_speed End Type ;------------------------------------------------------------------------------------------------------- ;LETS CREATE SOME PRIMITIVES TO USE LATER ;------------------------------------------------------------------------------------------------------- Global spark = CreateCube() ScaleEntity spark, .25,.25,.25 EntityColor spark, 255,168,0 HideEntity spark Global waypoint = CreateSphere() ScaleEntity waypoint, .5,.5,.5 EntityColor waypoint, 0,200,0 HideEntity waypoint ;------------------------------------------------------------------------------------------------------- ;CREATE SOME ENEMIES ;------------------------------------------------------------------------------------------------------- For num = 1 To 5 e.enemy = New enemy ;new enemy e\mesh = CreateSphere(16) ;create a sphere and store it in e\mesh e\speed = .1 ;set the speed of each enemy e\status = 1 ;set status to 1 PositionEntity e\mesh, Rand(-20,20),0,Rand(-20,20) ;place the enemies randomly EntityAlpha e\mesh, .5 Next ;------------------------------------------------------------------------------------------------------- ;MAIN LOOP ;------------------------------------------------------------------------------------------------------- While Not KeyHit(1) get_input() run_enemies() run_particles() check_hp() UpdateWorld RenderWorld gui() Flip Wend ;------------------------------------------------------------------------------------------------------- ;END MAIN LOOP ;------------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;FUNCTION GET_INPUT <--- GRABS INPUT FOR THE PLAYER ;----------------------------------------------------------------------------------------------------- Function get_input() If player_alive = 1 ;W key If KeyDown(17) Then TranslateEntity player, 0,0,.15 ;move it +z ;A key If KeyDown(30) Then TranslateEntity player, -.15,0,0;move it -x ;S key If KeyDown(31) Then TranslateEntity player, 0,0,-.15;move it -z ;D key If KeyDown(32) Then TranslateEntity player, .15,0,0 ;move it +x End If End Function ;----------------------------------------------------------------------------------------------------- ;FUNCTION RUN_ENEMIES <---EXOCUTES ACTIONS FOR EACH ENEMY ;----------------------------------------------------------------------------------------------------- Function run_enemies() For e.enemy = Each enemy ;for each enemy ;regardless of case, the distance to the player must be known, so we'll check it here Local dist# = EntityDistance(e\mesh,player) Select e\status ;select it's status Case 1 ;ON GUARD EntityColor e\mesh, 200,200,0 If dist# <= 10 ;if the distance is less than 10 or equal to it If player_alive = 1 e\status = 2 ;switch to state 2 End If End If Case 2 ;DROP NEW WAYPOINT Local x# = EntityX(e\mesh) ;grab the enemies' coordinates Local y# = EntityY(e\mesh) Local z# = EntityZ(e\mesh) ;place the waypoint at the location e\return_waypoint = CopyEntity(waypoint) PositionEntity e\return_waypoint,x#,y#,z# e\status = 3 ;then switch to case 3, which is pursue Case 3 ;PURSUE THE PLAYER EntityColor e\mesh, 200,0,0 ;red If dist# < 1 ;then attack! e\status = 4;change to attack Exit ;exit the loop End If If dist# < 12 ;first, check to see if we're 12 units away or less.... PointEntity e\mesh, player ;point enemy at the player MoveEntity e\mesh, 0,0,e\speed ;then make the enemy move in the pointed direction Else e\status = 5 ;set to status 5, which is return to waypoint End If Case 4 ;ATTACK player_hp = player_hp - 1 ;take 1 hp from the player e\status = 5 ;now return to the waypoint Local s_x# = EntityX(player) Local s_y# = EntityY(player) Local s_z# = EntityZ(player) Local num = Rand(3,8) ;create some effects create_particles(num,s_x,s_y,s_z) Case 5 EntityColor e\mesh, 200,0,200 Local dist_home# = EntityDistance(e\mesh,e\return_waypoint) ;get the distance home If dist_home# > .2 ;If we're further than .2 away... PointEntity e\mesh, e\return_waypoint ;point at home waypoint MoveEntity e\mesh, 0,0,e\speed ;move them forward Else If dist_home# <= .2 FreeEntity e\return_waypoint ;get rid of the waypoint mesh e\status = 1 ;and return to idle again End If Default e\status = 1 ;if somehow e\status = anything else, we'll set it to 1 End Select Next End Function ;----------------------------------------------------------------------------------------------------- ;GRAPHIC READOUTS <---This function prints readouts to the screen ;----------------------------------------------------------------------------------------------------- Function gui() Text 0,0, "Use WASD keys to move around." Text 0,10,"Don't let the spheres touch you or you'll lose hitpoints." Text 0,20,"Remaining HP: " + player_hp If player_alive = 0 Text 350,290,"You are DEAD!" End If End Function ;----------------------------------------------------------------------------------------------------- ;RUN PARTICLES <---This function runs the particles if there are any ;----------------------------------------------------------------------------------------------------- Function run_particles() For p.particle = Each particle p\alpha = p\alpha - p\fade_speed ;take fade speed from alpha EntityAlpha p\mesh, p\alpha ;set alpha to p\alpha If p\alpha <= 0 ;if alpha is <= 0 FreeEntity p\mesh ;free it Delete p Exit ;exit the loop Else p\speed_y = p\speed_y - .01 ;subtract from y speed MoveEntity p\mesh, p\speed_x, p\speed_y,p\speed_z ;move the particle End If Next End Function ;----------------------------------------------------------------------------------------------------- ;CREATE PARTICLES <--- THis is called when we need to create particles ;----------------------------------------------------------------------------------------------------- Function create_particles(num,x#,y#,z#) For s = 1 To num p.particle = New particle p\mesh = CopyEntity(spark) p\speed_x# = Rnd(-.2,.2) p\speed_y# = Rnd(.3) p\speed_z# = Rnd(-.2,.2) p\alpha = 1 p\fade_speed# = Rnd(.1) PositionEntity p\mesh, x,y,z Next End Function ;----------------------------------------------------------------------------------------------------- ;CHECK HP <---This checks the player's HEALTH each frame ;----------------------------------------------------------------------------------------------------- Function check_hp() If player_hp <= 0 player_hp = 0 If player_alive = 1 Local s_x# = EntityX(player) Local s_y# = EntityY(player) Local s_z# = EntityZ(player) Local num = Rand(15) ;create some effects create_particles(num,s_x,s_y,s_z) player_alive = 0 End If End If End Function

Blitzplotter (Posted 2011) [#2]

Exceptional piece of coding Drak, thanks for sharing! Hope you do not mind, I posted a slightly modified version of your code in the following thread as an include file to implement homing missiles/spheres in some JV-ODE physics car code :) http://www.blitzbasic.com/Community/posts.php?topic=89252#1066963 Last edited 2011

Drak (Posted 2011) [#3]

Glad someone found it useful!

Blitzplotter (Posted 2011) [#4]

@Drak, hell yeah, I feel myself being sucked back into B3D with physics(JV-ODE) at precisely the wrong time - I'm embarking on my penultimate course of study towards my degree with the OU, nevertheless I love excuses to play in B3D with physics & now a fantastic piece of code that lends itself to homing missiles - I'm curious to explore whether your code homes in on the y axis as well as the x & z axis. Not too hard to prove, but thats where I'm headin'....

Drak (Posted 2011) [#5]

It will home in on the Y axis in this program, but since the player is viewed from above here, and not allowed to move on the Y axis it's not relevant to this program. The "enemies" simply use the PointEntity() command so they actually can move and pursue in all axis.

Drak (Posted 2012) [#6]

2/3/12 Added a 6th state to the NPC enemies. Now they will wander randomly if they don't see the player. ;Waypoint Example By Drak, 3/8/2010 ;EDITED 2/3/12 ;************************************************************ ;THIS PROGRAM WILL: * ;Create a player mesh (a square) * ;Create some enemies (some spheres) * ;Make on-the-fly waypoints for the enemies to return to * ;Return the enemies to the waypoints * ;Also shows some some rudimentary AI * ;Shows some very simple particle effects as well * ;************************************************************ AppTitle "Drak's Waypoint Example" ;------------------------------------------------------------------------------------------------------- ;INITIALIZATION ;------------------------------------------------------------------------------------------------------- Graphics3D 800,600 SetBuffer BackBuffer() SeedRnd MilliSecs() Global player = CreateCube() ;create a cube for the player EntityColor player, 0,0,200 ;we'll make the player blue Global player_hp = 10 ;give the player 10 hit points Global player_alive = 1 ;player is indeed alive Global camera = CreateCamera() ;create a camera PositionEntity camera, 0,40,0 ;raise it up in the air RotateEntity camera, 90,0,0 ;point it down ;------------------------------------------------------------------------------------------------------- ;TYPES ;------------------------------------------------------------------------------------------------------- Type enemy Field mesh ;will hold the actual mesh Field return_waypoint ;will hold the handle of the return waypoint Field status ;holds a # referring to the enemies status Field speed# ;this will hold the speed of the enemy Field timer ;2/3/12 This will be a counter Field timer_max ;2/3/12 This is the counter's maximum Field steer_angle# ;2/3/12 This holds the enemy's steering angle End Type Type particle Field mesh ;holds mesh Field alpha# ;holds alpha Field speed_x# ;speed x Field speed_y# ;same Field speed_z# ;same... Field fade_speed# ;fade_speed End Type ;------------------------------------------------------------------------------------------------------- ;LETS CREATE SOME PRIMITIVES TO USE LATER ;------------------------------------------------------------------------------------------------------- Global spark = CreateCube() ScaleEntity spark, .25,.25,.25 EntityColor spark, 255,168,0 HideEntity spark Global waypoint = CreateSphere() ScaleEntity waypoint, .5,.5,.5 EntityColor waypoint, 0,200,0 HideEntity waypoint ;------------------------------------------------------------------------------------------------------- ;CREATE SOME ENEMIES ;------------------------------------------------------------------------------------------------------- For num = 1 To 5 e.enemy = New enemy ;new enemy e\mesh = CreateSphere(16) ;create a sphere and store it in e\mesh e\speed = .1 ;set the speed of each enemy e\status = 1 ;set status to 1 e\timer = 0 ;2/3/12 set timer to 0 e\timer_max = Rand(400,1000) ;2/3/12 pick a maximum timer PositionEntity e\mesh, Rand(-20,20),0,Rand(-20,20) ;place the enemies randomly EntityAlpha e\mesh, .5 RotateEntity e\mesh, 0,Rand(360),0 Next ;------------------------------------------------------------------------------------------------------- ;MAIN LOOP ;------------------------------------------------------------------------------------------------------- While Not KeyHit(1) get_input() run_enemies() run_particles() check_hp() UpdateWorld RenderWorld gui() Flip Wend ;------------------------------------------------------------------------------------------------------- ;END MAIN LOOP ;------------------------------------------------------------------------------------------------------- ;----------------------------------------------------------------------------------------------------- ;FUNCTION GET_INPUT <--- GRABS INPUT FOR THE PLAYER ;----------------------------------------------------------------------------------------------------- Function get_input() If player_alive = 1 ;W key If KeyDown(17) Then TranslateEntity player, 0,0,.15 ;move it +z ;A key If KeyDown(30) Then TranslateEntity player, -.15,0,0;move it -x ;S key If KeyDown(31) Then TranslateEntity player, 0,0,-.15;move it -z ;D key If KeyDown(32) Then TranslateEntity player, .15,0,0 ;move it +x End If End Function ;----------------------------------------------------------------------------------------------------- ;FUNCTION RUN_ENEMIES <---EXOCUTES ACTIONS FOR EACH ENEMY ;----------------------------------------------------------------------------------------------------- Function run_enemies() For e.enemy = Each enemy ;for each enemy ;regardless of case, the distance to the player must be known, so we'll check it here Local dist# = EntityDistance(e\mesh,player) Select e\status ;select it's status Case 1 ;ON GUARD EntityColor e\mesh, 200,200,0 If dist# <= 10 ;if the distance is less than 10 or equal to it If player_alive = 1 e\status = 2 ;switch to state 2 End If Else e\timer = e\timer + 1 If e\timer >= e\timer_max e\status = 6 ;switch to quick wander End If End If Case 2 ;DROP NEW WAYPOINT Local x# = EntityX(e\mesh) ;grab the enemies' coordinates Local y# = EntityY(e\mesh) Local z# = EntityZ(e\mesh) ;place the waypoint at the location e\return_waypoint = CopyEntity(waypoint) PositionEntity e\return_waypoint,x#,y#,z# e\status = 3 ;then switch to case 3, which is pursue Case 3 ;PURSUE THE PLAYER EntityColor e\mesh, 200,0,0 ;red If dist# < 1 ;then attack! e\status = 4;change to attack Exit ;exit the loop End If If dist# < 12 ;first, check to see if we're 12 units away or less.... PointEntity e\mesh, player ;point enemy at the player MoveEntity e\mesh, 0,0,e\speed ;then make the enemy move in the pointed direction Else e\status = 5 ;set to status 5, which is return to waypoint End If Case 4 ;ATTACK player_hp = player_hp - 1 ;take 1 hp from the player e\status = 5 ;now return to the waypoint Local s_x# = EntityX(player) Local s_y# = EntityY(player) Local s_z# = EntityZ(player) Local num = Rand(3,8) ;create some effects create_particles(num,s_x,s_y,s_z) Case 5 ;RETURN TO WAYPOINT EntityColor e\mesh, 200,0,200 Local dist_home# = EntityDistance(e\mesh,e\return_waypoint) ;get the distance home If dist_home# > .2 ;If we're further than .2 away... PointEntity e\mesh, e\return_waypoint ;point at home waypoint MoveEntity e\mesh, 0,0,e\speed ;move them forward Else If dist_home# <= .2 FreeEntity e\return_waypoint ;get rid of the waypoint mesh e\status = 1 ;and return to idle again End If ;CASE 6 ADDED ON 2/3/12 Case 6 ;WANDER EntityColor e\mesh, 0,200,0 ;turn it green ;KEEP THE WANDERING SIMPLE!!!! DON'T OVERCOMPLICATE THIS!!!!! e\steer_angle = e\steer_angle + Rnd(-.1,.1) If e\steer_angle > 1 Then e\steer_angle = 1 If e\steer_angle < -1 Then e\steer_angle = -1 TurnEntity e\mesh, 0,e\steer_angle,0 MoveEntity e\mesh, 0,0,e\speed/5 ;keep checking to see if the player is close enough to follow If dist# <= 10 ;if the distance is less than 10 or equal to it If player_alive = 1 e\status = 2 ;switch to state 2 End If End If Default e\status = 1 ;if somehow e\status = anything else, we'll set it to 1 End Select Next End Function ;----------------------------------------------------------------------------------------------------- ;GRAPHIC READOUTS <---This function prints readouts to the screen ;----------------------------------------------------------------------------------------------------- Function gui() Text 0,0, "Use WASD keys to move around." Text 0,10,"Don't let the spheres touch you or you'll lose hitpoints." Text 0,20,"Remaining HP: " + player_hp If player_alive = 0 Text 350,290,"You are DEAD!" End If End Function ;----------------------------------------------------------------------------------------------------- ;RUN PARTICLES <---This function runs the particles if there are any ;----------------------------------------------------------------------------------------------------- Function run_particles() For p.particle = Each particle p\alpha = p\alpha - p\fade_speed ;take fade speed from alpha EntityAlpha p\mesh, p\alpha ;set alpha to p\alpha If p\alpha <= 0 ;if alpha is <= 0 FreeEntity p\mesh ;free it Delete p Exit ;exit the loop Else p\speed_y = p\speed_y - .01 ;subtract from y speed MoveEntity p\mesh, p\speed_x, p\speed_y,p\speed_z ;move the particle End If Next End Function ;----------------------------------------------------------------------------------------------------- ;CREATE PARTICLES <--- THis is called when we need to create particles ;----------------------------------------------------------------------------------------------------- Function create_particles(num,x#,y#,z#) For s = 1 To num p.particle = New particle p\mesh = CopyEntity(spark) p\speed_x# = Rnd(-.2,.2) p\speed_y# = Rnd(.3) p\speed_z# = Rnd(-.2,.2) p\alpha = 1 p\fade_speed# = Rnd(.1) PositionEntity p\mesh, x,y,z Next End Function ;----------------------------------------------------------------------------------------------------- ;CHECK HP <---This checks the player's HEALTH each frame ;----------------------------------------------------------------------------------------------------- Function check_hp() If player_hp <= 0 player_hp = 0 If player_alive = 1 Local s_x# = EntityX(player) Local s_y# = EntityY(player) Local s_z# = EntityZ(player) Local num = Rand(15) ;create some effects create_particles(num,s_x,s_y,s_z) player_alive = 0 End If End If End Function