THE THIRD DIMENSION Easy Variables and ideas on how to use them. -------------------------------------------- If you are creating a game and have never used any variables before then don't worry! I will show you various ways to use easy variables even if you don't know what they are or how they work.I will also explain about variables and how to use easy variable routines.So lets get a variable into your game straight away. Create an Initial Condition in kit2 ( kit 1 see below!) then Edit the initial condition and give it this line of text- SETVAR(O,V2O) If you are using kit 1 then create a General Condition and add the above code to it,then set the Default Initial condition to whatever the number of the general condition is that you have just created (Probably Condition 1). Now RESET your game and try and shoot anything.You can't do it because we have just used a variable that disables the shooting ( which is variable V2O ). That shows how easy it is to use a variable.Very easy! So how can we best describe a variable so that you know how it works? A variable ( able to vary ) is like the weather.It can be sunny one day and raining the next,in other words it varies and that is just what a variable is like.You can make a variable change just as the weather does.The best thing is that YOU can change your variables to a different state just like God can change the state of the weather.You too can change the weather, that's if you can do a rain dance.(Yes I have mentioned some of this before but there are a lot of new things in here too!!) So if our weather was sunny before you added the line of code above because you could go around shooting anything then i have suddenly made it rain because now you can't.HA! So now we need to make the sun shine again by altering the same variable so that you can shoot again.So create a cube and give it this condition- IF ACTIVATED? SETVAR (15,V2O) This line of code is saying that if you touch the cube the computer will set our shooting variable ( variable V2O ) back to firing again.So try it out by touching the cube then firing. Yipee! its sunny again.Want to try it again? Press the reset button. So the SETVAR( set the variable ) command is setting our variable ( V2O )from one state ( being able to fire which is 15 ) to another state ( not being able to fire which is O ).E.g.- SETVAR (O,V2O) disables firing. SETVAR (15,V2O) enables firing. Not very exciting is it? but just think if the cube was made into a gun with other objects.You could then start your game off with no weapons available so you cannot fire,then find the gun and add an Object Condition to enable you to fire. System and User Definable Variables. ------------------------------------ There are two types of variables.There are System variables and User defined variables.The system variables are reserved for use by the Freescape system itself ( although you can alter them for your own use ).These are all listed in your user manual and they range from VO ( variable zero ) to V29. We saw last month how to use one of the system variables to disable/enable firing.The system variables ( which are the first 3O ) can also be used to detect your presence,move you around and simplify many other functions that you may use in your games. User defined variables start from 3O to 256 in kit 1 and 3O to 512 in kit 2.You can set these up yourself and use them in instruments,to hold values and a lot more.We will be looking at some examples to help you understand these and how they work. Here is one use for a user defined variable.This routine will count how many times that you have collided with an object and when it reaches a certain number it cause something else to happen e.g when it reaches 2O it could end the game. Start by making an Initial condition in kit 2 (or a general condition 1 in kit 1 which you must then set the initial condition in the default menu to 1)then edit it and give it this bit of code.- SETVAR (O,V33) This is telling the computer to set variable V33 to hold the value of zero.We use variable V33 because that is how old i am and simply because i want to.The variable is used in an initial condition (or general condition 1 in kit 1) because i want the computer to execute this command as soon as the game starts up at the beginning and to work once. Next we want to add another condition.This time it will be a General condition.This will be General condition 2 in kit 1 or General condition 1 in kit 2.Now give it this line of code.- IF VAR=? (2O,V33) THEN ENDGAME ENDIF This is telling the computer to keep an eye on variable V33 and if it reaches 2O then end the game. Now we need to make the variable V33 reach 2O as it starts at zero. Create a rectangle then move it onto the floor like a big doormat then give it this condition.- IF COLLIDED? THEN ADDVAR (1,V33) SOUND(3) ENDIF Now walk over the rectangle twenty times and the game should end.If it does not then raise the rectangle up from off the floor a little then try it again. Wow how exciting you may say but you could have lots of these rectangles scattered throughout your game or even apply the same condition to walls etc.You could also use it in conjunction with an instrument which actually shows the variable working. A point to note is that variables can be very fussy about how they are set out.You may find that when you have made some code that includes a variable, it just does not work when you know that it should.The answer is to swap the number concerning the variable around.E.g- SUBVAR(1,V44) change to SUBVAR(V44,1) It should then work if it previously did not. Here is another example of using a System variable ( remember these are variables from O to 29 ). First thing to do is to clear all previous code then create a cube (object 2).Then create a General condition then edit it to give it this condition.- IF VAR=? (15,V21) THEN INVIS (2) ENDIF This means that if you shoot anywhere fifteen times then the cube becomes invisible.Try it out!Reset the area and try again.If you have tried it out 5 million times then get some therapy! The 'IF VAR=? (15,V21)' command is saying that if the variable V21 equals a certain amount ( in this case 15 ) you have shot 15 times then make the cube invisible.Why do we have an ENDIF command? The answer is that an Endif command tells the computer that it is the end of the IF statement that starts on line 1. Right lets clear everything again then start again, this time creating 2 cubes side by side.colour one red and the other green.Or if you want,one bright purple and the other bright pink ( i won't tell anyone ).Now create an Initial condition and edit it so that it has the following- SETVAR (7,V5O) We use V5O because that is how old i look.HA! Create a general condition and give it this code- IF VAR=? (15,V5O) THEN SOUND(5) ENDIF Now give the red cube this condition- IF SHOT? ADDVAR (1,V5O) ENDIF Give the green cube this condition- IF SHOT? SUBVAR (1,V5O) ENDIF Now by shooting the Red cube you are adding 1 each time to Variable V5O and by shooting the Green cube you are taking one away each time.The general condition says that if the variable V5O reaches 15 then it will make the sound number 5 play. So now you should know how to use the ADDVAR,SUBVAR,SETVAR and IF VAR=? commands and also know the difference between System variables and User defined variables. Here are some more variable routines/ideas.- MOVEMENT VARIABLES Try using some of the movement variables! These are variables V0 to V5! Try this- Create a cube which is slightly raised off the ground and which you will be able to climb onto,something which should resemble a magic carpet after you have shaped and flattened it. Now make the carpet Moveable by clicking on the object Attributes button and selecting the MOV button (kit2) or changing the STATIC button (kit1) to Moveable.Now give the carpet this condition- IF COLLIDED? STARTANIM(1) ENDIF Next CREATE an Animation then EDIT it to include the following- INCLUDE(2) the 2 is the number of our carpet object START LOOP(50) MOVE(0,0,20) ADDVAR(20,V2) AGAIN Then reset the area and then climb onto the carpet! You should end up moving across the area on your magic carpet. Trying using another variable between 0 and 5 instead of V2 to see different effects! SENSORS AND VARIABLES Create a sensor in kit 1 or make an object in kit 2 into a sensor.Make sure that the sensor is set to shoot. Now create a local/area condition and add the following to it- IF VAR=?(15,V11) THEN ENDGAME ENDIF Now RESET the area and move towards the sensor.When you have been shot 15 times the area resets/the game ends.This is because variable V11 detects how many times you have been shot and because we have set it to 15,it will reset the game when you have been shot 15 times. INSTRUMENTS AND VARIABLES You can use an instrument(s) to show a variable working.This variable could be used to show your life diminishing via an instrument.Here is how- Create two instruments (one for health and one for lives) and edit instrument 1 to have the following- INSTRUMENT NUMBER 1 NAME = HEALTH VARIABLE 70 VALUE 1 = 20 VALUE 2 = 0 COL1 = 5 COL2 = 0 TYPE = VERTICAL Edit instrument 2 to have the following- INSTRUMENT NUMBER 2 NAME = LIFE VARIABLE = 71 VALUE1 = 3 VALUE2 = 0 COL1 = 5 COL2 = 0 TYPE = VERTICAL Now create an Initial condition and edit it to include- SETVAR (20,V70) SETVAR (3,V71) UPDATEI (1) UPDATEI (2) Now create and edit a General condition and give it the following code- IF VAREQ? (0,V70) THEN SUBVAR(1,V710 SETVAR(20,V70) ENDIF IF VAREQ? (0,V71) THEN ENDGAME You will then end up with 2 instruments controlled with variables.One will take away a portion of your health ( when activated ) until it reaches zero,then it will call up the other variable to take away one of your lives when the first variable reaches zero.When all your lives are gone,the game resets. You need to trigger the health instrument to work by adding some code to e.g. a floor object that when stood on looses you some life (it could be acid etc).The floor object has this condition- IF COLLIDED? SUBVAR (2,V70) ENDIF You could spice it up a little by adding some pepper,OOP's! I mean adding some text to a new text instrument ( Instrument number three ) and also add a sound of some kind.Like so- IF COLLIDED? PRINT(" YOU TROD IN ACID!",3) SOUND(2) SUBVAR(2,V70) ENDIF Now reset the area and add some movement controls to a border and then test it out.You must be in TEST mode (press F1) to see the instruments working.You must also have made some vertical instruments set in your border. REMEMBER! A VARIABLE is something that can hold any quantity that may change. A CONSTANT is something that represents any absolute value which never changes. By now you should have an idea of how to use various variables.Experimenting is the key! Remember that you cannot harm your computer by experimenting with variables.At the worst you will end up with a loop or a system crash,but you can always reload the 3D kit again.Remember to save regularly and have fun!!Help is only a phone call away - 01484 460888 and they will still serves chips at my chippy even if you make a mistake?? HA! Try experimenting with the examples above and try out some of the following- ADDVAR SETVAR ORVAR NEGVAR NOTVAR XORVAR SUBVAR CLEARVAR VAREQ? VARLT? VARGT? and many others! While we are on the subject of variables,it is worth noting the following.- There seems to be quite a few errors in the kit2 manual as regards to certain variable commands.Hopefully i will have given you the correct form for each of those listed here. Using the LIMIT command. It is listed as a Graphics command but i am sure that it should be classed as a Variable Modifier.The reason being that it is used to modify the limit amount of one variable and then stores the result into another variable. Example- SETVAR(1O,V31) This sets the value of V31 to 1O LIMIT(V3O,V31,O,8) but because the limit of variable V31 is set between O and 8,the value stored in Variable V3O will be 8. The first variable on the Limit command line after the first bracket is where the result of the second variable ( which has been modified due to the Setvar command on the previous line )after the bracket is stored.Zero and 8 are the minimum limit range and maximum limit ranges for variable V31.The result is that V3O equals/or holds the value of 8. Using the MAX command. It is correctly listed as a Variable Modifier but it gives the wrong result in the example contained in the kit 2 manual. Example- SETVAR(24,V3O) Variable V3O is set to hold the value 24. MAX(V31,V3O,12) The maximum value of variable V3O is set to hold the value of 12 (as V3O is the source variable) and the result is stored in the destination variable V31. So the end result is that Variable V31 will be set to 12 and not variable V3O as mentioned in the manual.This is because Variable V31 holds the end result as it is the destination variable and V3O is only the source variable. Using the MIN command. It is correctly listed as a Variable Modifier but it gives a misleading result in the example contained in the kit 2 manual. Example- SETVAR(-24,V3O) Variable V3O is set to hold the value -24. MIN(V31,V3O,12) The minimum value of variable V3O is set to hold the value of 12 (as V3O is the source variable) and the result is stored in the destination variable V31. So the end result is that Variable V31 will be set to 12 and not variable V3O as mentioned in the manual.This is because Variable V31 holds the end result as it is the destination variable and V3O is only the source variable.This can be quite misleading as variable V3O may equal 12 as mentioned in the manual after the computer has carried out the commands but the result is contained in V31. So to summarise- LIMIT is used to stop a variable/constant from holding a value less than the specified limit (the third variable/constant after the first bracket ) or greater than the limit (the fourth variable/constant after the first bracket )specified. MAX is used similar to LIMIT but only effects the highest value thus preventing the variable from holding a value greater than the one specified. MIN is used similar to LIMIT but only effects the lowest value thus preventing the variable from holding a value less than the one specified. In the example- LIMIT(V3O,V31,O,8) V3O is the destination variable where the computer stores the result V31 is the source variable where the computer gains the information from in the first place O is the lowest/miniumum limit of the variable allowed 8 is the highest/maximum limit of the variable allowed So this effectively tells the computer that the variable V31 (because its our source variable) can only use a value between O (the minimum number allowed) and 8 (the maximum number allowed) and then store the result in variable V3O ( because its our destination variable). Tony Hartley - A man who varies constantly!