![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image.jpeg\")
<\/p>\n
Figure 1: Creating a new project<\/p>\n
Name your project AI <\/em>and make sure the project is a 3D project. Once you’ve done that and set a location on your computer for the project, click the Create Project <\/em>button near the bottom shown in Figure 2.<\/p>\n Figure 2: Project setup screen<\/p>\n With the project created, you’ll first want to set up some folders in the Assets <\/em>window for the sake of organization. Right click in the Assets <\/em>window and select Create->Folder <\/em>to create a new folder. Call this folder Materials<\/em>. Then, create a second folder and name it Scripts<\/em>. Figure 3 shows how this should look.<\/p>\n Figure 3: Creating a new folder<\/p>\n When you’re done, the Assets <\/em>window should look like the one seen in Figure 4.<\/p>\n Figure 4: The Assets <\/em>window so far.<\/p>\n Next, create a floor for all the objects to stand upon. In the Hierarchy <\/em>window, select Create->3D Object->Plane <\/em>to create a plane object that will act as your floor as shown in Figure 5.<\/p>\n Figure 5: Creating a plane object.<\/p>\n Name this object Floor <\/em>and give it an X Scale <\/em>of seven and a Z Scale <\/em>of three. Once you’ve finished that, the Inspector <\/em>window with the Floor <\/em>object selected should look like the one seen in Figure 6.<\/p>\n Figure 6: Setting Floor <\/em>object properties.<\/p>\n Now you’ll want to create a new material for the Floor <\/em>to help distinguish it from other objects that will be placed in your scene. Under the Materials <\/em>folder in the Assets <\/em>window, create a new material by right clicking in the Assets <\/em>window and selecting Create->Material<\/em> shown in Figure 7.<\/p>\n Figure 7: Creating a new material<\/p>\n Once complete, name the material Floor<\/em> as shown in Figure 8.<\/p>\n Figure 8: The Floor <\/em>material<\/p>\n Near the top of the Inspector <\/em>window with the Floor <\/em>material selected, select the color picker seen in Figure 9.<\/p>\n Figure 9: Selecting the color picker.<\/p>\n Of course, the floor can be any color you wish, but in this example it will be set to a brown-red like color as shown in Figure 10.<\/p>\n Figure 10: The Unity color picker<\/p>\n Select the Floor <\/em>object from the Hierarchy <\/em>window, then under the Mesh Renderer <\/em>component select the small arrow next to Materials<\/em> as shown in Figure 11.<\/p>\n Figure 11: Preparing to change the material.<\/p>\n Click and drag the Floor <\/em>material from the Assets <\/em>window to the Element 0 <\/em>field under the Mesh Renderer <\/em>component in the Inspector <\/em>window like in Figure 12.<\/p>\n Figure 12: Setting the Floor <\/em>material as the Floor <\/em>object’s material<\/p>\n With the Floor <\/em>object finished, you will need to create some walls around the area to prevent the player from falling off the edge. Once again, go to Create->3D Object->Plane <\/em>to create a new plane. Name this plane Wall <\/em>and give it the same scale as Floor<\/em>, that being an X Scale <\/em>of 7 and a Z Scale <\/em>of 3. Then, create three more walls by selecting the object and pressing Ctrl + D three times. Once that’s done, place the walls around the floor using Table 1 as a reference.<\/p>\n Name<\/strong><\/p>\n<\/td>\n Position X<\/strong><\/p>\n<\/td>\n Position Y<\/strong><\/p>\n<\/td>\n Position Z<\/strong><\/p>\n<\/td>\n Rotation X<\/strong><\/p>\n<\/td>\n Rotation Z<\/strong><\/p>\n<\/td>\n<\/tr>\n Wall<\/p>\n<\/td>\n -35<\/p>\n<\/td>\n 21<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n -90<\/p>\n<\/td>\n<\/tr>\n Wall (1)<\/p>\n<\/td>\n -1<\/p>\n<\/td>\n 11<\/p>\n<\/td>\n -15<\/p>\n<\/td>\n 90<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n<\/tr>\n Wall (2)<\/p>\n<\/td>\n -1<\/p>\n<\/td>\n 11<\/p>\n<\/td>\n 13.5<\/p>\n<\/td>\n -90<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n<\/tr>\n Wall (3)<\/p>\n<\/td>\n 34<\/p>\n<\/td>\n 21<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n 0<\/p>\n<\/td>\n 90<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Table 1: Position and rotations of all Wall <\/em>objects.<\/p>\n In the example images, the walls have been left at their default color. However, if you wish you may give it a new color by creating a new material. Once this is all in place, you should reorient the camera so that it’s facing down at the floor, in a bird’s eye view. With the Main Camera<\/em> object selected set its Y Position <\/em>to thirty, Z Position <\/em>to zero, and X Rotation <\/em>to ninety as shown in Figure 13.<\/p>\n Figure 13: Setting up the camera object.<\/p>\n The scene is now set, so it’s time to make the player character. In the Hierarchy <\/em>window click Create->3D Object->Sphere <\/em>to create a sphere object. Name this object Player<\/em>, then click the Add Component <\/em> button near the bottom of the Inspector <\/em>window with the Player <\/em>object selected as shown in Figure 14.<\/p>\n Figure 14: Adding a new component.<\/p>\n Now, like in Figure 15, search for Rigidbody<\/em>. Once found, select the Rigidbody <\/em>component from the list to add the Rigidbody <\/em>to the Player<\/em> object.<\/p>\n Figure 15: Adding a Rigidbody <\/em>component.<\/p>\n Next, you need to assign the player a tag that will come in handy later on in the code. Click the Tag <\/em>drop down menu in the upper left corner of the Inspector <\/em>window and choose the Player <\/em>tag as shown in Figure 16.<\/p>\n Figure 16: Setting a new tag.<\/p>\n You’ll need to set a position for the player so it’s not underneath the Floor<\/em>. The example image places the player in the upper left corner, with an X position<\/em> of 26, Y Position<\/em> of 1, and Z position<\/em> of -9 as shown in Figure 17.<\/p>\n Figure 17: Positioning the player.<\/p>\n In order for your upcoming code to work properly you’ll of course need an object to attach it to. Once again, go to the Hierarchy <\/em>window and this time choose Create->3D Object->Cube<\/em>. Name this object Guard, <\/em>and add a Rigidbody <\/em>component and a NavMesh Agent <\/em>component using the Add Component <\/em>button in the Inspector<\/em> window. Then, set it somewhere near the upper left corner of the scene. When done, the Inspector <\/em>window for your Guard <\/em>object should look like the one in Figure 18.<\/p>\n Figure 18: The Guard <\/em>object as seen in the Inspector <\/em>window.<\/p>\n And the object in question should be placed in a similar position to the one seen in Figure 19.<\/p>\n Figure 19: Positioning the Guard <\/em>object.<\/p>\n Finally you’ll need an object to act as the Guard <\/em>object’s “eyes” that will alert the Guard <\/em>whenever the player touches it. One last time, go to the Hierarchy <\/em>window and choose Create->3D Object->Sphere <\/em>to create another sphere object. Name this object Looker<\/em>. From there you have no other components to add to it at this time. However, you’ll want to change the size of the object. With Looker <\/em>selected, change the following variables in the Transform <\/em>component under the Inspector <\/em>window.<\/p>\n Once you’ve done that, position the Looker <\/em>object so it sits in the upper middle part of the floor as shown in Figure 20.<\/p>\n Figure 20: Positioning the Looker object.<\/p>\n Now is a good time to give Looker <\/em>a unique material to help make it more like something you should avoid. In the Materials <\/em>folder in the Assets <\/em>window, right click and create a new material. Name this one Looker <\/em>and give it a bright red color. Once you’ve done that set this material as the Looker <\/em>object’s material to change its color. When finished the scene should now look similar to the one in Figure 21.<\/p>\n Figure 21: The Looker <\/em>object with the new material attached.<\/p>\n The only task left now is to create a navigation mesh for the Guard <\/em>to navigate with. At the top of the Unity editor lies the Window<\/em> menu. Select Window->Navigation <\/em>to open the Navigation <\/em>window as shown in Figure 22.<\/p>\n Figure 22: Opening the Navigation <\/em>window.<\/p>\n Select the Floor <\/em>object in the Hierarchy<\/em>, then in the Navigation <\/em>window select the Navigation Static <\/em>checkbox as shown in Figure 23.<\/p>\n Figure 23: Setting Navigation Static <\/em>to true.<\/p>\n Next, select the Bake <\/em>option near the top of the window as shown in Figure 24.<\/p>\n Figure 24: Switiching to the Bake<\/em> menu.<\/p>\n You’ll be taken to the Bake <\/em>menu where you can edit properties of the navigation mesh you’re about to create. In this example, there’s no need to edit anything. All you need to do is click the Bake <\/em>button near the bottom right as shown in Figure 25.<\/p>\n Figure 25: Creating a new navigation mesh.<\/p>\n At this point, Unity will request that you save your scene. Do so, and then the navigation mesh will be created. Now your scene will look like the one in Figure 26.<\/p>\n Figure 26: The current scene with the navigation mesh added.<\/p>\n Everything in Unity is now set, so it’s time to create the scripts needed to make this project work. In the Assets <\/em>window, right click and select Create->C# Script<\/em> and name this script Player<\/em>. Do this two more times, creating a script named Guard <\/em>and another named Looker<\/em> as shown in Figure 27.<\/p>\n Figure 27: Creating a new script.<\/p>\n When you’re done, the Scripts <\/em>folder in the Assets <\/em>window will look like the one in Figure 28.<\/p>\n Figure 28: The Scripts <\/em>folder.<\/p>\n The Player <\/em>script will be the first script to be coded. Double click the Player <\/em>script in the Assets <\/em>window to open Visual Studio and begin coding!<\/p>\n The Player <\/em>script is fairly simple, as all it\u2019s doing is allowing the user to move the ball object around. Underneath the class declaration, you’ll need to get a reference to the Rigidbody <\/em>component you created earlier in the project.<\/p>\n Right after that, in the Start<\/strong> function, you’ll command Unity to assign the Player <\/em>object’s current Rigidbody <\/em>component as the value of rb<\/em>.<\/p>\n With all this done, the Player <\/em>script will look like the one seen in Figure 29.<\/p>\n Figure 29: The Player <\/em>script so far.<\/p>\n Now that the value of rb <\/em>is assigned, you’ll need to allow the Player <\/em>object to move whenever any of the arrow keys is pressed. You’ll be using physics to move the object around, applying force to the object whenever the user presses any of the four arrow keys. To do this, just add the following code to the Update <\/em>function:<\/p>\n You now have a complete Player <\/em>script. The finished script will look like the one shown in Figure 30.<\/p>\n Figure 30: The complete Player <\/em>script.<\/p>\n Save your work and go back to Unity. This time, select the Guard <\/em>script from the Assets <\/em>window. In order to make the code for Guard <\/em>work you’ll need to add a using statement at the top of the script.<\/p>\n The Guard <\/em>object will have the Player <\/em>object as the value of the player<\/strong> variable. This will be needed later when you tell the Guard <\/em>object to pursue the player. Later on, the navmesh<\/strong> variable is declared to get the object’s NavMeshAgent <\/em>component. This will be later put to use when the Guard <\/em>pursues the player after they’ve been alerted of the player touching the Looker <\/em>object. In the Start<\/strong> function, you’ll need to set the navmesh <\/em>variable to the object’s NavMesh Agent <\/em>component by inputting the following:<\/p>\n This line will set a destination point for the Guard <\/em>object. In this case, it will get the Player <\/em>object’s current position and move towards that point. It will constantly pursue the player once it has been alerted. So now the question is, how does the alert process work? It won’t be coded in the Guard <\/em>script, but rather in the Looker <\/em>script. Before moving on to the Looker script, take a look at Figure 31 to review your code for the Guard<\/em> script.<\/p>\n Figure 31: The complete Guard <\/em>script.<\/p>\n Inside Looker, <\/em>you’ll need to once again declare the following variables.<\/p>\n After that, go ahead and comment out the Start <\/em>function as it will not be needed for this script. Jump down to the Update <\/em>function and add the following code:<\/p>\n This is where the bulk of the project’s action is happening, so let’s break it down. First, depending on the value of the movingDown<\/strong> boolean, the object this script is attached to will either be moving up or down. Once it reaches a certain point, it will change direction. Next, the Looker <\/em>will lower the value of reset based on real time. Once that timer is below zero, it will get the Guard <\/em>script on the Guard <\/em>object and disable it, whereupon the Guard <\/em>object will move to the last known player position before that point and then stop moving. Looker <\/em>will also reenable its collider so that the whole process can start again. By this point, the script should look like the one shown in Figure 32.<\/p>\n![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image-1.jpeg\")
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\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n ![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image-12.jpeg\")
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<\/p>\nThe Code<\/h2>\n
private Rigidbody rb;<\/pre>\n
rb = GetComponent<Rigidbody>();<\/pre>\n
![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image-28.jpeg\")
<\/p>\nif (Input.GetKey(KeyCode.UpArrow))\r\n rb.AddForce(Vector3.forward * 20);\r\nif (Input.GetKey(KeyCode.DownArrow))\r\n rb.AddForce(Vector3.back * 20);\r\nif (Input.GetKey(KeyCode.LeftArrow))\r\n rb.AddForce(Vector3.left * 20);\r\nif (Input.GetKey(KeyCode.RightArrow))\r\n rb.AddForce(Vector3.right * 20);<\/pre>\n
![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image-29.jpeg\")
<\/p>\nusing UnityEngine.AI;\r\nNext, declare the following variables just underneath the class declaration.\r\npublic GameObject player;\r\nprivate NavMeshAgent navmesh;<\/pre>\n
navmesh = GetComponent<NavMeshAgent>();\r\nThen, in the Update <\/em>function, just add a single line of code:\r\nnavmesh.destination = player.transform.position;<\/pre>\n
![](\"https:\/\/www.red-gate.com\/simple-talk\/wp-content\/uploads\/2018\/08\/word-image-30.jpeg\")
<\/p>\npublic GameObject guard;\r\nprivate float reset = 5;\r\nprivate bool movingDown;<\/pre>\n
if (movingDown == false)\r\n transform.position -= new Vector3(0, 0, 0.1f);\r\n else\r\n transform.position += new Vector3(0, 0, 0.1f);\r\nif (transform.position.z > 10)\r\n movingDown = false;\r\nelse if (transform.position.z < -10)\r\n movingDown = true;\r\nreset -= Time.deltaTime;\r\nif (reset < 0)\r\n{\r\n guard.GetComponent<Guard>().enabled = false;\r\n GetComponent<SphereCollider>().enabled = true;\r\n}<\/pre>\n