SimplePath 1.11
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1. Now let s get an agent moving around in the world between two patrol points First we ll need a PathManager object to solve all of the paths for us Find this prefab located in SimplePath gt Main gt Resources Next we need the actual agent that moves around the world Find the Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved Actor Patrol prefab located in the directory SimplePath gt Examples gt Resources gt Prefabs Drag one of these into the scene and place him somewhere on the floor Then add two PatrolNode objects to move between These are located in SimplePath gt Examples gt Resources gt Prefabs Again place these objects somewhere on the floor Your scene should appear as follows File Edit Assets GameObject Component Terrain Window Help Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved Now that we have all of our objects we need to make a couple of connections so that the objects know about each other The PathManager needs to know about the terrain for which it is solving paths Select the PathManager object from the Hierarchy window Now select2. First notice that the code decouples planning from the terrain If you want to create a more general purpose planner ex for a GOAP then you can consider inheriting from the AStarPlanner or Planner class and defining your own planning world by inheriting from IPlanningWorld The GetTraversalCost function is particularly important to note because this defines the heuristic for the planner Additionally you can define your own planning success conditions by inheriting from the SuccessCondition class The SuccessCondition determines when the plan is complete For example a path plan is complete when the current node equals the goal node which you can see in the ReachedGoalNode SuccessCondition class However you may want a more complicated success condition such as only ending the plan once it finds a node that is near the goal node or that is near the goal node and close enough to another friendly agent Finally if you want to define your own navigation targets take a look at INavTarget Right now SimplePath supports navigation to a target object or position but you can define your own type of target by inheriting from INavTarget Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 20
3. the Path Terrain Component from the Inspector window and connect it to the PathGridWithObstacles Inspecto 7 PathManaael Untagged Transform Script Path Terrain Component Max Number Of Nod Per Planner Max Number C ers nber Of Cycles Per Frame Max Number Of Cycles Per Planner Next we need to tell the agent about the PathManager that is solving his paths and the PatrolNodes that he is supposed to move between So select the Actor_Patrol from the Hierarchy window Locate the Path Agent Component from the Inspector window and find the Path Manager variable Connect this to the PathManager object in the scene Finally locate the Interaction_Patrol script from the Inspector window and look at the Patrol Nodes variable Set this array to size 2 and connect the first element of the array to the first PatrolNode you created and the second element to the second PatrolNode Your inspector window should look something like the following image Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved 11 m Path Agent Component Script Script Paths Path Manager Debug Path Colo De Deb Debug B v Steering Agent Component Script Script SteeringAgentComponente Arrival Distance Debug Path Colo Debug Goa Debug Goa E 0 25 Debug Sho v a Navigation Agent Component Script m Script NavigationAgentCompone Use Path Smoothing v
4. with a grid terrain but is structured to support any terrain type whether it be a navigation mesh waypoint graph or grid All of this starts with the Path TerrainComponent The PathTerrainComponent simply provides a place for the terrain to live it just owns an IPathTerrain member variable Every terrain component should inherit from this component For example the PathGridComponent inherits from Path TerrainComponent and provides a wrapper for the PathGrid as well as a place for all of the tunable grid parameters SimplePath comes with three different Grid prefabs PathGrid PathGridWithObstacle and PathGridWithObstaclesAndHeightmap The difference being the obstacles and the heightmap support The prefabs that support obstacles allow for obstacles to be rasterized into the terrain which allows the agents to pathfind around obstacles with a FootprintComponent The PathGridWithObstaclesAndHeightmap also has a component that provides a heightmap this is the HeightmapComponent UnityTerrain component This component specifies Unity Terrain object as a heightmap and therefore this component does not work with iPhone and Android though Unity announced that Unity 3 4 will support the Unity Terrain object You only need this component if you are planning on having uneven terrain in your scene If you need uneven terrain on iPhone or Android you can implement your own heightmap component by inheriting from the IHeightmap interface When a heigh
5. Copyright 2011 Alex Kring Rights Reserved 2 Introduction The purpose of SimplePath is to provide game developers with a robust toolkit for pathfinding within the Unity game engine Like most pathfinding software SimplePath was designed for use with any game genre SimplePath provides everything you need to get your AI navigating in game While the software provides simple steering and a grid terrain representation the main focus is on robust pathfinding The system is designed to allow you to easily plug in your own steering system and terrain representation if you desire In the following sections of this document I will describe how you can utilize SimplePath for your own games Starting at the highest level there are primarily three game structures of importance These are the agent the PathManager and the terrain These three entities define the pathfinding universe The agent is the GameObject that moves around the world the PathManager is responsible for servicing requests from many agents and all of this takes place on the Terrain where the agent is moving The following screenshot of the PatrolWithObstacles example scene depicts these major components Edit Assets GameObject Component Terain AssetStoretools Window The agent is the white cylinder the terrain is the white grid and the PathManager has no physical representation Additionally there are several other notable elements depicted in the abo
6. Interaction Patrol Script LI script inte action Patrol Patrol Nodes Size Element 0 PatrolNode Element 1 PatrolNode Replan Interval 3 402823 38 Now you can press play and watch your agent navigate between the two patrol points Next let s make the agent s job a bit more complicated by adding some objects to the scene Locate the Obstacle Box prefab in SimplePath gt Main gt Resources and drag a few of these into the scene Place these objects on the floor and size them to your liking just make sure you don t cover up the PatrolNodes or the agent Press play again and the agent should navigate around these objects Your final scene should resemble the image below Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 12 File Edit Assets GameObject Component Terrain Window Help Maximize on Pla If you have gizmos turned on you should notice a bunch of red rectangles below each obstacle These rectangles represent the footprint of each obstacle When the agent is navigating he Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved makes sure to avoid any terrain covered by a footprint In the next section I cover more details about each of the objects mentioned in this t
7. SimplePath 1 11 User s Manual This document is protected under copyright law The contents of this document may not be reproduced in any form without the written consent of Alex Kring This document is provided as a manual for the SimplePath software The information in this document is subject to change without notice Contents 3 Grdocpm E 4 Tutorial Creating Your First Scene i aac sees enne nennen 4 Path ue A 14 Terrain Representatie eses aia buxo ved tuse 15 Create Your Own Terrain Representation asas aaa ae na a e na 16 nets 16 APEM e 17 Interaction COMPONEN KC assess antennas Raa aaa 17 NavigationComporient eeu tette tres eer te ee a e a sexe 18 Path Component Se fade aaa et 18 Steering Component cecinit e eene e eda es 18 Creating Your Own Agent 00 cecccececeesesececeeeeeeeeeeaaeaeceeeceeeeeaaeaeceeeeeseeaaaaeaeceeeseeesaaaeceeeeeeeeeeaaeaeeeeeeeeeeaaaa 19 Advanced CUSTOMIZATION 20 Confidential information for paying customers of SimplePath software
8. f these agents is that they each have a different interaction script Each agent also has a Path Agent Component Steering Agent Component and Navigation Agent Component Next I will describe each of these components starting with the interaction script Interaction Component The interaction script controls the agent s behavior The navigation requests originate in this component For your game you might call this the behavior the control state or something else The interaction script is there to show how you can plug in SimplePath to your AI decision logic Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved 17 behavior tree GOAP FSM etc In a commercial game I would not recommend tying a single interaction script to an agent Instead you should attach some sort of InteractionComponent which is responsible for running any type of interaction on the agent where the interaction may be pushed onto the InteractionComponent from some BrainComponent that is making the decisions about which interaction to run Navigation Component The navigation component controls navigation requests Attach this component to any GameObject and it will be able to navigate around the world Any GameObject with a NavigationAgentComponent should also have a RigidBody SteeringAgentComponent and PathAgentComponent This component has a Use Path Smoothing Inspector variable which de
9. mation for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved File Edit Assets GameObject Component Terrain Window Help Now select the grid object you just created and take a look at it in the Inspector We re going to modify some of the grid properties to make the navigation space match the floor Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved thGridWithObstacles Tag Untagged Prefal Transform osition 11 4007 otation Path Grid Component Script LI cript B PathGridComponent Number Of Rows 10 Number Of Columns 10 Cell Size Debug Show Debug Colo B 7 obstacle Grid omponent Script Script obstacleGridCor Obstructed Cell Colo Show v Take a look at the Path Grid Component The following variables are used to change the terrain e Number of Rows e Number of Columns e Cell Size Play around with these values and notice how they affect the grid Once you have a fair understanding set the appropriate values that provide you with a grid and floor that are roughly the same dimensions which should look like this Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved File Edit Assets GameObject Component Terrain Window Help
10. more nodes than this variable then the search will fail Increasing this variable will allow you to solve longer and more complicated paths but it will also increase the amount of memory The memory for each planner is pre allocated pooled to avoid expensive Garbage Collection operations e Max Number of Planners The size of the planner pool Increasing this number will allow you to service more path requests at once but it will also increase memory size If the number of agents concurrently requesting paths exceeds this number then several of those requests will not be serviced For example if there are 25 agents requesting paths and this variable is set to 20 then 5 of those agents will not have their paths solved Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 14 e Max Number of Cycles Per Frame Each frame the PathManager runs for this number of A cycles If you increase this number performance will decrease but paths will be solved in a fewer number of frames e Max Number of Cycles Per Planner Each frame a single planner can run for a maximum of this number of A cycles The PathManager is the authority over all pathfinding and is the single channel that all pathfinding must pass through Next I will describe more details about the terrain Terrain Representation The terrain is the space where all navigation takes place SimplePath comes
11. ponent Script im script h SteeringAgentComponentc Arrival Distance Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved 18 e Arrival Distance when the agent is within the arrival distance of their destination the navigation request will be complete and the agent will stop moving Imagine this as a sphere around the destination position Once the agent gets inside this sphere he stops e Max Speed the fastest speed at which the agent can move e Look Ahead Distance how far the agent looks ahead on his path If this value is very small the agent will stick tightly to his path If it is very large then he will follow his path more loosely however if you make this value too large or too small the agent may get stuck e Slowing Distance how far the agent must be from his destination before he begins to slow down Set this value to 0 if you don t want the agent to slow down near his destination e Acceleration Rate how fast the agent accelerates in meters per second squared in XZ e Gravitational Acceleration Rate how fast the agent accelerates in meters per second squared in negative Y Creating Your Own Agent SimplePath comes with three agent prefabs but for most games you will likely be creating your own agent You can create agents that just solve paths and don t actually steer along them or you can create agents that will sol
12. prefab as an example And that s it Everything else should be setup the same just as if you were using a grid terrain representation One thing that might be different however is obstacle avoidance Grids are particularly good at dynamic obstacle avoidance since we rasterize the obstacles into the grid via the FootprintComponent If you decide to use a waypoint or nav mesh terrain representation you may have to employ more complicated steering or local planning as well Uneven Terrain The most significant addition in SimplePath 1 1 is the ability to navigate across uneven terrain Supporting uneven terrain requires you to first create a Unity Terrain object and then link it to the Path Terrain object Path Grid Component Script LI Script PathGridComponent Number Of Rows 170 Number Of Columns 170 Cell Size 10 Debug Show ee Optional Heightmap 4 Terrain Terrain After this value is set the agents should successfully navigate across your Unity Terrain object SimplePath will only use this object as a heightmap and we only use the SampleHeight function This function is called in one location as shown in the code snippet below Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 16 public float GetTerrainHeight Vector3 position i EE m heightmap null i return Origin y else i return m heightmap SampleHeight position You
13. rmation for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved 4 And the project window should look like this Now let s start adding some objects to the scene Add a cube GameObject GameObject gt Create Other gt Cube and stretch it out a bit in the X and Z axis This will serve as our floor so name this object Floor Next in the Mesh Renderer component select Element 0 of Materials and choose the Ground_Mat material This should render your floor black which will make it easier to see the next objects we re going to add Drag the camera over toward the floor object we just created and point it down the negative Y axis Finally create a directional light place it behind your camera and your scene should look something like the following Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring All Rights Reserved 5 File Edit Assets GameObject Component Terrain Window Help Camera Preview Next we will create the terrain Locate the PathGridWithObstacles prefab located in the directory SimplePath gt Main gt Resources Drag one of these objects into the scene and you should see a white grid Place the grid just above the floor s surface and align the two objects Your scene will look something like the following don t worry if the proportions are different than the following screenshot we will fix that next Confidential infor
14. termines if it generates smooth or rough paths By default smooth paths are generated If you want very blocky paths that only go between the centers of the grid cells then set this value to false this behavior may be desirable for certain turn based games Note that pathsmoothing should work for any terrain representation Path Component The path component is the agent s interface for pathfinding Any GameObject with a PathAgentComponent can generate path requests This component has a Path Manager Inspector variable which determines which PathManagerComponent is in control of servicing the path requests for this PathAgentComponent Typically there will only be one PathManager in the entire game but you have the flexibility to create multiple PathManager objects and have each manager control different sets of agents based on this Inspector variable this behavior may be desirable if you want to separate path requests for flying enemies and ground enemies Steering Component The steering component takes in a list of points and moves the agent along those points In other words it takes the output of the PathAgentComponent the path solution and steers the agent along that path SimplePath provides you with a very simple steering solution If you want something more complex you should hook your steering system into this component There are quite a few steering parameters so I will go over each one in detail m Y Steering Agent Com
15. tmap is present the planner will be sure to account for the uneven terrain by changing the steering to steer over uneven slopes smoothly and by changing the planner to weight the different heights in the terrain There is one other noteworthy variable and it is on the ObstacleGridComponent Iam referring to the Rasterize Every Frame variable When this is set to true the dynamic obstacle grid will be raserized updated every frame For certain games this may be too expensive If you need to better control the performance impact from the obstacle grid you should uncheck this box and manually call the Rasterize function only when necessary ex only when obstacles have moved The rest of the terrain variables are self explanatory Next I will explain how you can make your own terrain via the IPathTerrain interface Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 15 Create Your Own Terrain Representation Every terrain type should inherit from this interface ex grid nav mesh waypoint graph If you want to use your own terrain representation there s a few things that you ll need to do Create your terrain data structure and inherit from IPathTerrain Use PathGrid as an example 2 Create a component for your terrain and inherit from PathTerrainComponent Use the PathGridComponent as an example 3 Attach your component to a GameObject Use the PathGrid
16. utorial PathManager This section describes the PathManager in detail including all of the PathManager s tunable parameters and the different ways the PathManager can be used The PathManager is embodied by the PathManagerComponent and is responsible for doing most of the work Namely it solves all of the path requests over time The simplest task is for the PathManager to receive a request to find a path from point to point B and respond with the list of points from to B as soon as possible For most games you will only need one Path Manager but SimplePath provides the flexibility to specify any number of PathManagers where each PathManager can be responsible for managing a different set of agents each agent specifies his PathManager in the Inspector window of the tunable variables that you find in the Inspector window for the PathManagerComponent are there for controlling performance except for the Path Terrain Component variable 7 Path Manager Component Script Script Path ManagerComponent Path Terrain Component B PathGridWithObstacles c Max Number Of Nodes Per Planner 200 Max Number Of P 20 Max Number Of C Frame 100 Max Number Of Cy Here they are described in detail e Path Terrain Component Defines the terrain on which the PathManager is solving paths e Max Number of Nodes Per Planner The size of the node pool for each planner If a path search ever explores
17. ve figure The yellow line is the path the red wire frame sphere is the goal the green spheres are patrol nodes the large red cubes are obstacles the red area beneath each obstacle is the footprint of that obstacle the large white rectangles represent the bounding box of each obstacle and the black square is the floor Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 3 Quick Start If you re only interested in the bare minimum to getting things up and running here s what you need to do Place the following three GameObjects in your scene SimplePath comes with prefabs for each of the following GameObjects e PathManager e PathGridWithObstacles e Agent Wander You ll then need to hookup the following variables in the Inspector window e Agent gt PathAgentComponent gt PathManager e PathManager gt PathTerrainComponent Press play and the agent should randomly wander around the grid Next I will describe the step by step process to create the PathWithObstacles scene Tutorial Creating Your First Scene First open up Unity and create a new project Then import the SimplePath package by selecting Assets gt Import Package gt SimplePath Now create a new scene and name it FirstScene Your resulting project should look something like the image below Window File Edit Assets GameObject Component Terrain Confidential info
18. ve paths and steer along them The latter case is more common and so I will describe a rough guideline for creating your own fully functional agent your setup may slightly differ depending on your game 1 Select the GameObject that you want to turn into an agent 2 Add the NavigationAgentComponent 3 In the Inspector window inside the RigidBody component find the Constraints gt Freeze Rotation variable Make sure the X Y and Z boxes are checked Also on this component make sure the Use Gravity box is unchecked 4 In the PathAgentComponent hookup the Path Manager variable to a PathManagerComponent that is already in the scene After completing all of these steps that agent should be able to move around the world To get him to move from code you can call MoveToPosition or MoveToGameObject on the NavigationAgentComponent and wait for the OnNavigationRequestSucceeded or OnNavigationRequestFailed message to be passed to the GameObject Or you can attach one of the Interaction scripts to this GameObject ex Interaction Wander Confidential information for paying customers of SimplePath software Copyright 2011 Alex Kring Rights Reserved 19 Advanced Customization There are several other aspects of planning that you can customize which may be attractive to more advanced users Next I will briefly discuss the customization mechanisms that SimplePath offers which have not already been mentioned in previous sections
19. will likely want your agents to stick to the floor and look realistic when moving across all the various bumps in the terrain To control this you can modify several variables First consider the variables on the SteeringAgentComponent The max speed acceleration rate and gravitational acceleration rate all affect how the agent looks when he moves If you want the agent to stick to the floor more then you can increase the gravitational acceleration rate But keep in mind that there needs to be a balance between the gravitational acceleration rate and the acceleration rate The acceleration rate only affects the XZ acceleration of the agent while the gravitational acceleration rate only affects the Y acceleration The other value to consider is the mass of the agent which is stored on the rigidbody The downward force is computed as follows F gravity agent Agravity In other words SimplePath applies a downward force to the agent that is equivalent to the mass of the agent multiplied by the gravitational acceleration rate variable Next I will discuss all of the different components on the agent Agent The agent is the GameObject that physically moves around the world Typically this will be one of the enemies in your game SimplePath comes with three example agent prefabs which are the Agent_Wander Agent_Chase and Agent_Patrol all located in SimplePath gt Examples gt Resources gt Prefabs The only difference between each o
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