Top Down Tank Tutorial: Health and Death

 

    I think this is the last piece of the code for the tank, all taking damage, gaining health, and dying. Let's get to it.

     The tank has two main colliders, one regular physical collider with a rigid body, and then one slightly larger set as a trigger zone. Things that can hurt the tank like bullets, explosions, enemy shells, all have their own assigned tags. When they cross into the tanks trigger zone, that first bit of script in front of the "If" function is checking the tag to trigger the according health loss. One thing I always forget, and it takes a very long time to debug if you're sleep deprived, the Collider from the On Trigger block needs to be hooked up to the Compare Tag block with that elusive green line.

    After the compare/if bit, you can see the Get Variable block pull the tanks current health, subtract the Enemy_Bullet_Damage, and then it feeds that up to a set variable block to update the tanks health.

     The next bit is updating the players health in the UI. This bit is also called On Start (top block) so that the UI shows the players health as full. When the player takes damage, this bit updates the Public_Player_Health and then sends a message (Custom Event) to the scene controller (Dungeon Keeper) telling it to set the UI health to be the same as the Public_Player_Health.

    This next block I call "popping" the UI, which I go over more thoroughly here. Basically changing the color and size of the UI element just for a moment so the player actually notices something has updated.

    This last bit, since Top Down Tank is but a simple game, checks if the players health is less than or equal to zero, and then sends the player to a scene that just says "You Died" if the math checks out. So, now that we have covered losing health and death, I'll show you the whole script and then we'll move to gaining health.

    Crash course, the crate in the ruins in the cover image is a health pick up. It has a trigger with a check looking for collision with the player character. When it gets that hit, it sends a message to the dungeon keeper and the player to update their health records, and here's how it goes.

    The first block is a Custom Event waiting to receive the message "Health40" from a crushed crate. Now comes the tricky part. We don't want the player to raise their health past the tanks maximum, so we first have a check to see if the players health is at least (Less or Equal) 40 points less than full. This game (unfortunately for me) let's the player select from a number of different tanks with different levels of health, all of which are stored in a list called T6_UpgradeList (Get Variable) from which we are pulling the first slot (List - Get Item - 0) because this tank is not upgrades. If they had two health upgrades, we'd be pulling from Index: 1.

    Once we have the health, we subtract the potential health boost (40) and then check if the player has taken at least 40 points of damage. If yes, we just go ahead and add (Set Variable - Add) the 40 points back to the players health.

    If the players health is less than 40 points from being full, we just go back to the upgrade/health list, pull the maximum recorded health, and set the player back to full. This sounds annoying and fiddly, but it's very easy to slip up and allow the players health to grow forever line they're the blob.

     Anyway, thanks for reading. Maybe next I'll go more in-depth about how pick ups work. If this is helping, maybe throw me something on Ko-Fi, or buy a Kaiju game. I'll probably keep making these either way.

    Stay fresh, cheese bags.

Top Down Tank Tutorial: Mouse Tracking

 

    Now for a very important piece of the top down tank, the jank way I make the turret track the players mouse. We'll start from the simple bits and get more fiddly from there.

    I think I've mentioned this method before in the NPC Turret Tutorial, but we'll go back through anyway. There is an empty object attached to the tank called the Sight. It's only job in the world is to look to where the mouse beacon (Mouse_Sight) is in the world at any given time so the turret can get the coordinates. So, On Update -> Look At: Variable - Mouse_Sight. All simple and good.

    Just like the sight, we're having this chunk of script fire every update because we want the turret pointing constantly at the players mouse. We're grabbing the rotation (Get Rotation) from the mouse sight from the panel just above (Object Variable: Sight) and then taking only the Y and W coordinates from that rotation data. The turret in this game is essentially 2D and stuck on the Y axis. No need for Z and X.

    We're taking the Y and W to create a new, more basic rotation and then forcing the tank turret (Set Rotation) to adopt that rotation. Still pretty simple.

     So, with this we are essentially treating the view as a 2D image, getting the position of the mouse on the screen, and the projecting that (Physics - Raycast) down until it hits something (Raycast Hit - Get Point). There is an invisible object in the game we mentioned earlier called the Mouse_Sight that this script is attached to and this script is constantly moving the object to where it thinks the mouse should be landing in the scene so the turret can track it. It's sort of a pain in the ass.

     Last an most important bit, you need to set the Field of View in your camera to 20 or higher. The higher that number, the broader the plane from which your mouse can project and the more accurate the mouse tracking will be. It is lower than 20 by default. So, make sure to fix that.

     That's it for now. I'll try to have what I expect to be the last part up next week. If this is helping, maybe throw me something on Ko-Fi, or buy a Kaiju game. I'll probably keep making these either way.

 

Top Down Tank Tutorial: Firing

 

    Now for a very important bit if you're making a tank, firing.

    Firing, as you might have guessed, is tied to the left mouse click, which according to Unity is Mouse 0. Right after the On Keyboard Input block, we're going to a Cooldown set to 0.5 seconds. So, the player can only fire a shell every 0.5 seconds at the most. In other games, I've implemented an ammo counter and I would also have a check after the cool down to see if ammo is greater than zero, but this is a nice simple tank game. Just a cooldown for this one.

     The Get Variable block is here to orient the shell. The tank has an invisible little object attached to the barrel of the tank just beyond the box collider so the shell doesn't collide with the tank and explode right at spawn. This spot is the BulletPoint. We've attached the Variable Block to a Get Forward block so the shell knows which and then multiplying the forward force by 3 all across the board. So, Get Forward multiplied by a Vector 3 with all slots set to "3."

    Now we're finally spawning our shell into the world with an Instantiate block. The Original slot is tied to a prefab of the tank shell. You can see a Get Position and Get Rotation block on the left side feeding into the Instantiate block. Those two are tied back to the Get Variable: BulletPoint block from the last slide. So, the shell spawns in at the Bullet Point and facing the right direction, which is away from the tank.

    Then we finally move onto the Add Force block to get this shell moving. The little green line between the Instantiate and Add Force is hooked up the denote the force is being applied to the rigidbody of the newly created object. (Note: Your ammo will need a rigidbody if you want this to work. Play with the mass. It can be fun) The force Mode is set to Impulse because I wanted this to mimic a firing round and lose momentum after a bit, and the Force input comes from the Multiply block in the last slide.

    So all the blue square was us figuring out what direction to push and how hard to push it, and then we dump all that information into the Add Force block to actually execute it.

    Also I have this bit because I wanted the tank to make noise when it fires. The position is also set to the BulletPoint. And just below this is a zoom shot of everything so you can reference how it all hangs together.

     That's it for now. Come back soon to learn more about how this tank works. Maybe throw me something on Ko-Fi and I can justify making some more Visual Script write ups, or buy a game. I have a lot of other half-baked scripts to share.

 

 

Top Down Tank Tutorial: Camera Controls

 

    Second bit of the tank tutorial, let's talk very quickly about how the camera is controlled. So, first of all, the camera isn't free floating or attached to the tank. It's instead attached to an empty object that follows the tank around, which let's me also detach it and move it around to see points on interest. 

    The empty object has this little bit of script that keeps it over the player when it isn't going after a point of interest. Every frame (On Update Block) the script grabs the position of the player (in this case called Player_Head) and sets its own position to match. Pretty simple.

    Then we have rotation controls. Anyone who read the last post will recognize these as copies of the rotation controls from the tank, but linked to the Q and E keys instead. Again, using rotation based on the self in the Rotation block. 

    I know this tutorial was a bit short, but the camera controls aren't all that complex, and do they really need to be?

     That's it for now. Come back soon to lean more about how this tank works. Maybe throw me something on Ko-Fi and I can justify making some more Visual Script write ups. I have a lot of other half-baked scripts to share.

 

 

Top-Down Tank Tutorial: Movement

 

    I made a simple little top down tank a while ago, and some parts were hard, some were easy. I thought I would share how I threw it together. So, first thing is first. We're going to talk about how the player gets the tank to move around the map.

 

 

    The controls for this tank are split into two main parts, basically turn and move. This chunk of script is built to rotate the body of the tank. We'll start with the top bit first. On Keyboard Input set to Hold, meaning the script will fire continuously while the A key is being held down. That's linked to a Cooldown block set to 0.02 seconds. I didn't want the tank to spin around too fast, and the Cooldown is there to regulate that. After that, we can see a Rotate block set to self and rotating -1 on the X axis, meaning the tank will turn left relative to itself.

    The second line on this chunk, coded to the D key with a positive 1 on the X axis, is obviously meant to turn the tank right.

    This bit moves the tank forward (relative to itself, not the world or camera). Again, we're using the On Keyboard with a Hold setting, linked to W for forward. Again, a Cooldown block so this isn't firing every frame, and then we are going to a Set Velocity block to move the tank forward. (Note that the tank needs to have a collider and a rigid body for this method to work.) 

    Down on the lower portion, we have a Get Forward block attached to This, so the script can figure out where the front of the tank is. That's fed into a Multiply block and pulling the tank speed from Object variables (which is set to 5 for this tank) and then fed to the Set Velocity block. So, the tank is given a continuous velocity of 5 in the "forward" direction as long as the player holds W.

    The Back portion of the script is virtually the same as the Forward chunk, except you can see the tank speed is multiplied by -1 before it is fed into the whole velocity thing. So, the tanks speed is set in the negative and the direction is reversed. Giving it a second look, I wish I had set the Cooldown slightly longer to make the tank reverse slower than it moves forward, but that's just a little personal preference. 

     That's it for now. Come back soon to lean more about how this tank works. Maybe throw me something on Ko-Fi and I can justify making some more Visual Script write ups. I have a lot of other half-baked scripts to share.