Airship Sub & Boat Tutorial. Made by King and Cheese

Transcription

1 Airship Sub & Boat Tutorial Made by King and Cheese

2 Contents Introduction What you should already know 3 What you will learn 3 Let s start Opening up our scene 4 Adding some movement 5 Turning 8 Ascending and descending 9 Modifying our script Current progress 10 Keeping us in line 11 Slowing down 11 Stop the sliding 12 Fixing our axises 14 Making the propellers spin 15 Sub and boat What s next? What to do now? 15 Legal Stuff Terms of use 16

3 Introduction What you should already know How to use Unity s interface Basic JavaScript How not to cry like a baby if (or when) you mess up What you will learn Adding forces to a rigidbody Constraining those forces Fixing a models rotation, pivot and axises The ability to be totally AWESOME* * results may vary

4 Let s Start Opening up our scene Let s start this by first opening up our scene, you can find it in the project panel under island/scene (look right). Now that we are in our scene, hit play to see what we ve got. Well, we have an airship and some nice terrain, but absolutely nothing for actual game play. Don t worry, we ll fix that soon. So let s begin by making us move.

5 Adding some movement Adding movement is really pretty easy. First things first though, we need to add a rigidbody to our gameobject to be able to add forces to it. You can do this by clicking on the airship in the Hierarchy panel and then clicking on Component/Physics/Rigidbody Now set the RigidBody s settings to those in the photo below

6 Since we have a rigidbody now, we ll start making our script. So let s create a new JavaScript and rename it to airshipsubboat or something else if you want, but that s what I like to call it. Next, open up airshipsubboat and delete anything that the computer might have put in there for us and add this code to your script: var isboat = false; var force = 0.0; var maxspeed = 0.0; var turnforce = 0.0; var maxturnspeed = 0.0; var changingaltitudeforce = 0.0; var maxchangingaltitudespeed = 0.0; var maxheight = 0.0; var maxdepth = 0.0; var softener = 0.0; var curspeed = 0.0; var props : Transform[]; private var inputz = 0.0; private var inputx = 0.0; private var inputy = 0.0; function Start() rigidbody.maxangularvelocity = maxturnspeed; function Update() curspeed = Mathf.Clamp(rigidbody.velocity.magnitude, 0, maxspeed); //are we trying to move backwards or forwards? inputz = Input.GetAxis("Vertical"); //are we trying to turn left or right? inputx = Input.GetAxis("Horizontal"); //are we trying to go up or down? inputy = Input.GetAxis("UpAndDown"); function FixedUpdate() if (inputz > 0.0 ) rigidbody.addrelativeforce (0, 0, force); else if (inputz < 0.0) rigidbody.addrelativeforce (0, 0, -force);

7 Now I can start explaining what all this does piece by piece: function Start() rigidbody.maxangularvelocity = maxturnspeed; Simply changes our rigidbody s maxangularvelocity (or max turn speed) to our maxturnspeed (duh). For more about a rigidbody s variables go here: function Update() curspeed = Mathf.Clamp(rigidbody.velocity.magnitude, 0, maxspeed); Just changes curspeed to how fast our rigidbody is moving. We do this because it is easier (for us and the computer) to check our rigidbody s speed once rather then several times per FixedUpdate. It also limits our speed with Mathf.Clamp, we ll learn about that later. //are we trying to move backwards or forwards? var inputz = Input.GetAxis("Vertical"); //are we trying to turn left or right? var inputx = Input.GetAxis("Horizontal"); //are we trying to go up or down? var inputy = Input.GetAxis("UpAndDown"); This is where we get all our input. function FixedUpdate() if (inputz > 0.0 ) rigidbody.addrelativeforce (0, 0, force); else if (inputz < 0.0) rigidbody.addrelativeforce (0, 0, -force); This is where we add the force that makes us move with rigidbody.addrelativeforce which basically pushes our rigidbody forward (or backward) relative to it s own local coordinate system. For more on rigidbody.addrelativeforce go here:

8 Now that we know what our script does (so far), we ll save our script and add it to our airship and change the variables to those in the photo below, but leave Props empty. Turning Let s add some spin to this project. Start by putting this code in the FixedUpdate function: if (inputx > 0.0) rigidbody.addrelativetorque (0, turnforce, 0); else if (inputx < 0.0) rigidbody.addrelativetorque (0, -turnforce, 0); As you can see turning is quite simple, all we do is add a bit of torque to make us spin the way we want on our Y axis that over time get s faster (each FixedUpdate adds to the last one). For more on rigidbody.addrelativetorque go here: If you want to know more about torque in general go here:

9 Ascending and descending Add this code in the FixedUpdate function to get us going up and down: if (!isboat) if (inputy > 0.0 && rigidbody.velocity.y < maxchangingaltitudespeed) rigidbody.addrelativeforce (0, changingaltitudeforce, 0); else if (inputy < 0.0 && rigidbody.velocity.y > (0.0 - maxchangingaltitudespeed)) rigidbody.addrelativeforce (0, -changingaltitudeforce, 0); A bit more goes into ascending and descending than the other two inputs. As you can see, we can only use them if we are not a boat (because most boats don t fly or go underwater, intentionally, last time I checked). Second thing that s different is we check if our vertical speed (rigidbody.velocity.y) is less than our maxchangingaltitudespeed before we add any force to our rigidbody.

10 Modifying our script Current progress If we try our game now we would have a working system that lets us fly our airship like, well, an airship. But in case you have not noticed, there are some problems with our script. Like we can go higher or lower than our max height or depth or if we run into something it spins us around in a way we can t get back from. If this is some how what you want, feel free to leave now it won t bother me. But I strongly recommend you continue into this tutorial if you want your end product to be more like the one in the completed scenes (you might want to have a look at them now if you haven t already).

11 Keeping us in line Probably the worst thing going on right now, is us flipping all around when we run into something or going above or below our limits. So we some how have to constrain some of our axises. This is where the beauty of Mathf.Clamp comes in. One of the many useful little things Unity comes with. So without further to do, let s add this code in our FixedUpdate function under everything else in there: transform.position.y = Mathf.Clamp(transform.position.y, maxdepth, maxheight); transform.rotation.x = Mathf.Clamp(transform.rotation.x, 0, 0); transform.rotation.z = Mathf.Clamp(transform.rotation.z, 0, 0); I guess I should explain what Mathf.Clamp does. It s real simple, all it does is put a limit on a value. For example: transform.position.y = Mathf.Clamp(transform.position.y, maxdepth, maxheight); Changes our Y position to the Mathf.Clamp value which is set to our current Y position and is constrained to stay within our maxdepth and maxheight value s. For Unity s explanation on Mathf.Clamp feel free to go here: Slowing down Anybody who has tried out what we have so far would have probably noticed that we don t slow down over time because we set our rigidbody s drag to 0. Now we could just set it to something like 0.01 but it would be affecting us all the time and in some cases keeping us from reaching our max speed. So I find it easier to just add drag through script and only when we aren t trying to move that way. Let s add this to our script (in FixedUpdate under everything else): //soften are movment if(inputx == 0.0) rigidbody.angularvelocity *= softener; if(inputy == 0.0) rigidbody.velocity.y *= softener; if(inputz == 0.0) rigidbody.velocity.x *= softener; rigidbody.velocity.z *= softener;

12 Basically what this does, is lower our current velocity in a certain direction. Like if we are not trying to turn (thus inputx = 0.0) we start to slow down our turn speed but not our other forward or vertical speeds. We do the same thing with inputy but with the current speed we are moving on the Y axis. But as for inputz we slow down both our rigidbody s X and Z velocity. That s because our rigidbody s X and Z (and Y for that matter) velocity is measured on the global axises. Therefore we need to slow down both axises. Stop the sliding Maybe you have noticed that if you re going fast and then take a hard turn you seem to slide around. Well that s because we do, but thankfully andeeee posted this lovely piece of code on the Unity forums: //thanks andeeee for this little nugget of code rigidbody.addforce(-vector3.project(rigidbody.velocity, transform.right) * (rigidbody.mass / 5) ); If you want to increase (or decrease) the affect, just replace (rigidbody.mass / 5) with your own value or even add a var just for that. But I ll leave that to you. Oh, and if you want to check out the forum I found it in, here is a link: Fixing our axises Next I think we ll make our propellers spin. But before we do that, we have to center all our propellers. We will basically be doing it the same way as the Unity website suggests. Here is a link: Let s start with front right propeller and focus on it (select it and push the F key). Now make an empty gameobject by going to GameObject/create empty.

13 We ll rename it to frontrightprop and move it around so it looks like it s in the center of the propeller. Make sure you look at it from a top view, a side view and a back view (you might find the 4 split layout useful for this).

14 Now add frontrightprop as a child to our airship and make ftrightprop a child of it. Well done, you have just re-centered a gameobject. Repeat this process with the other 3 propellers so your hierarchy looks like the photo to the right. But in case you are lazy, I made a re-centered prefab you can use. You will find it in the project panel in the completed/prefabs folder named recenteredairship. Making the propellers spin Last on the to-do list is making our propellers spin. All we have to do for this is add this bit of code in our script (in FixedUpdate under everything else): //spin the propeller/s for (i = 0; i < props.length; i++) props[i].transform.rotate(0, 0, curspeed); This is a pretty simple piece of code. All it does is rotate each one of our propellers by our curspeed. But to make it work we have to add each one of our propellers to our props variable. Set it s size to 4 and drag and drop each propeller into it:

15 Sub and boat By now you re probably wondering why this is the airshipsubboat tutorial. It is because it is very simple to modify our script to work with a boat or submarine since they use the same movement as an airship, so all you really need to do is change a few variables to make it work. To make a sub you just change maxdepth to -250 (or however low you want to go) and maxheight to 0 or so. To make a boat you just change maxdepth to 0, maxheight to 50 or so and isboat to true and you have a boat. What s next? What to do now? Really anything you want to do. Unity let s you do all sorts of things. Here are just a few suggestions: Rewrite our script to give it a buoyancy effect. Make the propellers spin different ways. Modify the script to make a wake when we move as a boat. Ect., etc., the list could go on forever (or at least a VERY long time). But really, get out there try some crazy ideas! Make some killer games! Whatever you do, just go have some fun!

16 Legal stuff Terms of use Well there aren t really any. The models and scripts are free to use, you can take little bit s and pieces of the project if you want. All I ask is that you have some fun with whatever you do.