Cannon

Brought to you by the Delta Project, modelled by Dwayne Oliva

The Delta cannon is the perfect heavy weapon for land or sea use, whether you want to sink pirate ships or merely reduce towns garrisoned by your enemies. Its advanced ballistic control will allow ballistics engineers to show off their skills, while simplified automatic targeting will suit those in a hurry to wreak havoc among some band of insolent vassals.

Like all Delta historics, the cannon is an accurate model of a historic cannon. It has a barrel whose elevation is controlled by pulling out and pushing in a wooden wedge. The wick really burns, the chassis really recoils, the barrel flashes and the cannonballs explode into small pieces.

Equipped with a choice of cannonballs that would make any siege engineer's heart skip a beat, the Delta cannon is a must for next time you need to storm a castle - or defend one.


Features

  • Working cannon modelled on historic weapon
  • Realistic fire and recoil effects
  • Choice of four cannonballs (roleplay, Linden damage, Test and skulls)
  • Automatic targeting system and detailed manual tuning of placement
  • Selectable ball speed
  • Range up to 500m
  • Texturable front panel
  • Access control to let you share your cannon with a group or with all users
  • Test target with detailed information on each shot
  • High detail, low lag, optimised scripting for best possible performance under all conditions
  • Free updates for life

Quick start instructions

  • Rezz the box, open it and copy the contents to inventory.
  • Find the folder called '[Delta] Cannon'
  • Rez the object called 'Cannon'
  • Rez the test target somewhere you can see within 96m of the cannon
  • Touch the cannon to take control
  • Touch the test target so it knows to send reports to you
  • Type /5 ball test to load test ammo.
  • Type /5 target Test target (capitalisation must be exactly right!). The cannon will rotate and the barrel will raise (assuming you put the target somewhere it can reach)
  • Type /5 fire.

You should receive a report telling you what happened to the cannonball you fired. Don't worry about all the details; only the test balls talk to you in this way. Once you understand how the cannon works you can load some real ammunition.


Manual

  1. What's in the box
  2. Using the cannon
  3. Ammunition
  4. Advanced targeting
  5. Voice commands
  6. Damage and statistics
  7. Hints and tips
  8. Troubleshooting

1. What's in the box

In the folder you have unpacked you will find

  • the cannon
  • a test target
  • the texture used on the front panel in case you need to restore it
  • a quick reference card
  • your Delta service terminal
  • an affiliate vendor in the shape of a pile of cannonballs. If you set out a cannon for public use, you may like to set this out nearby in case users want to get their own cannon - you receive 20% of each purchase.

2. Using the cannon

To use the cannon it is first necessary to click on the wooden base. Only one person may control the cannon at any time. The owner can control who has access to the cannon. Whether or not the owner, you can only use the cannon when you are standing within 5m of it.

Before you fire the cannon you will want to target it on something. There are two ways to target the cannon: automatic targeting and manual targeting. Targeting will be discussed in detail in section 4. In this section we shall assume you know the coordinates of the point you want to hit.

Suppose you need to train fire on an enemy gun emplacement at <45,87,26>. Simply type

/5 target 45,87,26
The gun will rotate to point at that point and provided it is in range the barrel will raise to an angle suitable for hitting it. If instead you get a message that the barrel cannot point downwards, you will have to move the cannon elsewhere. If you are told that the cannon cannot reach that far you can try increasing the speed. At 75m/s the cannonball can travel nearly 500m on the level.

Not included

Now you have to decide what it is that you want to fire at the enemy. Choose the roleplay or linden cannonball based on the combat system you are using; or choose the skulls if you merely want to frighten them. For example to load the roleplay cannonball you would type /5 ball roleplay. Names for all the cannonballs are given in section 3.

To fire the cannon you simply type /5 fire.

If you leave the cannon unused for two minutes you will lose control of it. You can also relinquish control by typing /5 release.

You will also lose control of the cannon if you take control of another cannon in the same sim.

Note: The cannon base and its barrel are two separate objects. If you move the base using the sl editor, the barrel will not move. You must type /5 reset to align the barrel with the base again. If you delete the cannon base the barrel will be left behind: just delete that too.

Setting up the cannon for other users

You can set access to the cannon to public or group to allow others to fire it. If you want them to be able to rotate the base, you must edit it in the sl editor and check 'allow anyone to move'. If you don't do this they will only be able to set targets using the target command.

You may wish to prevent users from changing ammo, so that you are sure that the cannon will only be firing ammo that is legal in the sim where you rezzed it. Simply set the kind of ammo you want used and then type /5 ammolock on. This disables the ball command. Only the owner may use the ammolock command.

3. Ammunition

There are five cannonballs available:

NameUsageDescription
rpKinetic damageFor use in roleplay sims where collision with a fast physical object causes damage (DCS for example). Kinetic ammo does 5 damage under CCS.
ldbLinden damageFor use damage enabled land (where you see a heart at the top of the screen)
testTestThis does no damage but emits a signal picked up by the test target, which will tell you how close your shot landed.
skullSkullThese do no damage at all but are great for lowering enemy morale.

To activate a cannonball simply type /5 ball NNN where NNN is its name.

4. Advanced targeting

First a little notation. Any object can be rotated three ways: it may help to think of a plane flaying horizontally. It can climb or fall (pitch); it can turn left or right (yaw); or it can turn upside down (roll). To target a cannon, we first need to turn (yaw) to face the target; the correct angle is called the azimuth. Then we need to raise or lower the barrel (pitch) to get the height and therefore the range right; the correct angle is called the elevation. We don't worry about roll with cannons because it would be difficult to achieve and would anyway only mean that the cannonballs came out rotated which, as they are spherical, wouldn't make any difference.

Establishing the azimuth is a piece of cake because the cannon ball travels in a straight line when viewed from above and so is bound to get to the right place provided it doesn't hit anything on the way. Establishing the elevation is harder because gravity pulls the cannonball out of a linear path so you have to shoot over your target's head and hope the ball drops on them. Happily applied mathematics allows us to work out the correct angle quite precisely and if you care to look up how to do it you can start here. The automatic targeter has this all built in so if it all looks a bit daunting just use that.

The cannon barrel rotates on an axis mounted through its center (conceptually - if it actually ran through the center the cannonball couldn't get out). It can thus be raised or lowered to vary the target (pitch). However, it cannot move in the horizontal plane (yaw); for that the base must be rotated.

To select a target manually proceed as follows:

  1. Using the sl editor, rotate the base until its forward axis (which in sl terms is the y axis of the root prim) points at the object you want to target
  2. Type /5 reset to align the barrel
  3. Decide how far you want to pull the wedge out. There are 100 positions, with 0 making the barrel horizontal and 100 raising it as high as it will go. Type /5 wedge 50 for example to set position 50, which is half way along.
  4. Fire a test shot to judge how close you are to the target
  5. The commands /5 up and /5 down edge the barrel up and down one notch if you need to adjust vertically. If you need to adjust horizontally you will have to go back into the editor and try again.

The automatic targeter will calculate approximate azimuth and elevation to hit a specified target. For this you use the target command. Simply add the location you want using the system sl uses in the top bar of the viewer. So to target the point <41,90,26> type

/5 target 41,90,26
This will try to work out the wedge position best suited to hit the target. It will always rotate the base correctly but depending on the location of the target it may not be able to find a barrel angle. You may need to increase the speed, but generally, the lower the speed the more accurate the targeting, do don't simply crank the speed up to max before you start.

For objects within 96m you can replace the coordinates by the object name. You must get this exactly right, which is quite easily achieved by editing the object and copying its name.

As with manual targeting the up and down commands can be used to fine tune the elevation of the barrel. There is no way to fine tune the azimuth but the automatic targeter usually gets this right, so it is probably the elevation you need to tweak.

If you use the editor to change the location or rotation of the base, the cannon will no longer have the correct orientation for the target; you will have to target it again.


If you are still in any doubt the next diagram should make everything clear.

Using the test target

The test target works with the test cannonballs to help with artillery practice. Place the target somewhere suitable facing the cannon. Touch the target so that it will send its reports to you (after 30 minutes you will need to touch it again if you are still using it). Then do one of the following.

  • Target the cannon manually to try to hit it.
  • Record the target location and use the target command to target it.
  • If the target is within 96m simply type /5 target Test target.
Fire the cannon with test ammo loaded. You should get an instant message like the following (it uses instant message so that it can work even if not in the same sim):
Test shot detected
Detonation caused by object collision
Collision with Test target
Distance from target 0.888981
Fwd: -0.112747 Left: -0.037155 Up: 0.881020
Taking this line by line:
  • The first line just tells you the shot was heard by the target.
  • The second tells you why the cannon ball detonated: either because it hit a prim or because it hit the ground. If you get no message probably the cannonball went off world or entered a different sim from the one with the target in. This means you need to practice quite a lot more.
  • The third tells you either what prim the ball hit or where on the ground it landed
  • The fourth tells you the distance. This isn't a lot of help because if the ball missed the target altogether, which happens quite often, it may have gone quite a long way behind before it found anything to hit.
  • The fifth gives you the impact location with respect to the target. The forward coordinate is likely to be negative (behind the target) and if you managed to hit the target it will be quite small. The left and up figures then allow you to estimate the azimuth and elevation errors respectively; usually the elevation is most seriously wrong.
Not quite right
Notes:
  • If you missed the target altogether the left and up errors aren't a lot of use but should at least enable you to tell whether the ball went over or under
  • The target is mod so you can always make it larger
  • If you orient the target wrong the final line won't be so helpful, because the coordinates given use the targets axes
  • For serious pedants: in the event that you do manage to hit the target the place where the ball detonated is not exactly the same as the point where it impacted the target. The target reports the former, because it is useful even if you miss the target completely. Firing a cannon isn't like shooting an arrow where absolute precision is required; as cannonballs do area damage, it's enough to get fairly close.

If you are not the owner of the cannon you can get a target by using the /5 givetarget command.

5. Voice commands

Voice commands are given on channel 5.

All commands are case insensitive.

Basic operations
targetTarget a named object or a location of the form x,y,z
fireFire the cannon
resetReset, aligning barrel correctly if you have moved the base
releaseStop controlling the cannon
ballLoad a named cannonball type
Advanced
wedgeSet percent by which wedge is drawn out - this controls the angle of the barrel
speedSet speed (must be more than 15 and less than 100)
upRaise barrel (supply an argument to raise it more than one notch)
downLower barrel (supply an argument to raise it more than one notch)
Access (owner only)
publicAnyone may control the cannon
privateOnly the owner may control the cannon
groupAnyone in the group to which the cannon is assigned may control it
Other
shieldTexture the shield - supply a UUID for the texture (owner only)
ammolockFollow by on or off. Ammo lock prevents users from changing the ammo. Only the owner may use this command.
statGet cannon settings
givetargetGet a target for use with test ammo
helpGet this card
guideRead online guide (you are doing that now)

6. Damage and statistics

  • Time between shots: 5 seconds
  • Cannonball speed: 15-75 m/s variable
  • Effective range of weapon: 500m

RP cannonball

  • RP system dependent damage on all avatars within 20m

LD ammo

  • 100 damage to all avatars within 10m
  • 30 damage to all avatars within 20m

Skulls

These are unscripted and do no damage.

7. Hints and tips

  • Go to the advanced menu (Ctrl-Alt-Shift-D) and uncheck Limit Select Distance. Now you can edit a distant object to find its location or name.
  • If the object you want to target has a long name it may take a while to type, and the capitalisation must be exactly right. To save effort, edit the object, copy the name from the edit box and paste it into the /5 target command.
  • If your cannon is public or group and you want users to be able to change the target using the editor, remember to set the object so that anyone can move it.
  • Remember that you can repeat recently used command by holding down the control key and pressing the up arrow. This helps if you want to fire the gun several times or repeatedly target an avatar who is moving around.
  • The cannon likes to rezz a little way above the ground because of its sculpt wheels. Move it onto the ground using the editor, then take control and type /5 reset; the barrel will drop into place.
  • Although targetting avatars by name is fun, it isn't necessarily the best way to use the targeter. It's quite unlikely the targeter will work so precisely as to hit the avatar direct; and if the avatar moves around the cannon will not follow. A cannon is not an assassin's weapon; it's more suited to driving enemies away from some point you want to capture. Work out where that point is and target that.

8. Troubleshooting

Don't try this at home

Please read the following before reporting a problem.

  • The cannon doesn't respond to commands! Did you click it to get control? Are you standing within 5m of it?
  • The barrel is at an odd angle (or missing altogether) Take control of the cannon and type /5 reset.
  • My cannon is stuck! Rezz a new gun from the product box. If you have lost the box you can get a new one by rezzing the certificate. If you have lost that too you can get one from a redelivery terminal.
  • I can't retexture the shield The texture must be full perms and you must use its UUID not its name. The easiest way to get this is to right click on the texture in inventory and select Copy Asset UUID. Now go to the chat window, type /5 shield followed by a space and then press Ctrl-V to paste the UUID in.
  • I deleted the gun but the barrel is still there! Because the barrel rotates independently of the base it is rezzed as a separate object. Just delete it - your cannon will rezz a new one next time you use it.
  • I got a message starting INTERNAL ERROR Not your fault! Those should never happen. Contact support and give as many details as possible.
If you need to report a problem, please use the support board in the Delta shop. This will put you straight in touch with a member of staff if one is online and will allow you to leave an IM otherwise.


Change log

v1.0
  • Release