A tank with 5 turrets (types)
Blitz3D Forums/Blitz3D Programming/A tank with 5 turrets (types)
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| Hi I have a tank with 5 turrets and instead of writing out the info for all turrets within the type Id like to do an array of turret types within the tank type. How would I do this? |
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I'm a bit rusty but you prolly want something like this:Type turretType Field rotation# Field elevation# End Type Type tankType Field turrets.turretType[4] End Type tank.tanktype = New tanktype For n = 0 To 4 this.turretType = New turretType this\rotation = 45 this\elevation = 10 tank\turrets[n] = this Next |
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| thanks \ how would i update the turrets during the game? |
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Well, following on from the above code, this will update the 4th turret:tank\turrets[3]\rotation = 90 tank\turrets[3]\elevation = 45 |
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| thanks that was what I was looking for I just have a little problem understand this part: For n = 0 To 4 this.turretType = New turretType this\rotation = 45 this\elevation = 10 tank\turrets[n] = this Next Why does tank/turrets[n] = this? Is it so the tank type knows which turret type belongs to it? |
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| Yes. In the tankType definition, 'Field turrets.turretType[4]' simply says that "the field called 'turrets' is an array to hold pointers to 5 turretTypes". Then, in the For/next loop, we actually create the 5 turretType instances and store the pointers to them in the tankType array. |
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| thanks, is there any way of doing this but having the turrets the same type as the tank?? This would simplify things greatly. If the turret was another tanktype |
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| is it possible to get some more flexible design, say, if you sometimes want a tank to have just one turret, in other cases you'd want it to have 15 or so. Do you have to assume the worst case, and how much memory is wasted doing so (I mean for each unused turret element)? |
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| Slenkar, I think big10p gave what you requested. The following line shows a pretty easy access to the turrets and their properties. tank\turrets[3]\rotation = 90 What other style of structure did you have in mind? Cheers to big10p for an excellent, patient description! |
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| I need to use the same type for every object in the game, the method above is good but uses 2 different types, |
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| mpausi: Yes, it is possible to make things more flexible - a couple of methods spring to mind. Sorry, but I'm in a bit of a rush at the mo but I'll try and get back with some code soon. Of course, anyone else is free to post their own methods in the meantime. :) Slenkar: Not sure why you would need to contain everything in a single type but I guess you have your reasons. Given that restriction, the only why to achieve this is to 'hardcode' the various fields into a single type, like:
Type tankType
tankName$
turret1_rot#
turret1_ele#
turret2_rot#
turret2_ele#
turret3_rot#
turret3_ele#
turret4_rot#
turret4_ele#
turret5_rot#
turret5_ele#
End Type
However, this is alot less flexible than using the array method as you can probably imagine. Actually, there are other ways like using a bank to hold the various turret properties and using peek/poke to read/write them, but this makes things unnecessarily complicated, IMO. Nacra: You're more than welcome! ;) |
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| If every tank has a max of MAX_TURRETS turrets and turrets are specific to tanks then there is no need for a separate type OR hardcoding each turret as separate pair of fields then const MAX_TURRETS=5 type tank field tank_name$ field tank_x# field tank_y# field tank_z# field tank_rotation# field tank_number_of_turrets field turret_elevation#[MAX_TURRETS-1] field turret_rotation#[MAX_TURRETS-1] end type |
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| thanks big10p for your help So, J.P. you are saying put each turret characteristic in its own array? I worked out how to do it by creating a type instance for each turret so they are destructible |
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| JP: Yes, that is a more sensible way of keeping everything in a single type. Feel a bit of a plonker having missed that. :P As I said, I'm a bit rusty and see you have subtracted 1 when dimensioning a blitz array with a constant. I wasn't sure if blitz arrays worked this way or not so glad you put me straight on that, too. ;) mpausi: this is one method of allowing tanks to have different amounts of turrets: Type turretType Field rotation# Field elevation# Field nextLink.turretType End Type Type tankType Field tankName$ Field totalTurrets% Field turretList.turretType End Type ; Create a tank. tank.tankType = New tankType tank\tankName$ = "Mega Crusher" ; Add 5 turrets with random rotation and elevation. For n = 1 To 5 add_turret(tank, Rand(360), Rand(45)) Next ; Display current tank settings. print_tank(tank) Print Print "Press a key to change rotation & elevation" Print "of turret 3 ..." Print WaitKey() ; Now change the rotation and elevation of turret 3. this.turretType = get_turret(tank, 3) this\rotation = 123 this\elevation = 456 ; Display new tank settings. print_tank(tank) WaitKey() ; Kill the tank. free_tank(tank) End ; ; Add a new turret to the specified tank. ; Function add_turret%(tank.tankType, rotation#=0, elevation#=0) ; Create a new turret type. newTurret.turretType = New turretType ; Set initial turret settings. newTurret\rotation = rotation newTurret\elevation = elevation ; Add turret to tank's linked list. newTurret\nextLink = tank\turretList tank\turretList = newTurret ; Increment the total count of turrets belonging to this tank. tank\totalTurrets = tank\totalTurrets + 1 Return tank\totalTurrets End Function ; ; Return a pointer to the specified tank turret. ; Function get_turret.turretType(tank.tankType, turretNo%) ; Return NULL pointer if turretNo is invalid. If (turretNo < 1) Or (turretNo > tank\totalTurrets) Then Return Null ; Walk along turret linked list until we reach the requested turret. this.turretType = tank\turretList For n = tank\totalTurrets-1 To turretNo Step -1 this = this\nextLink Next ; Return pointer to the requested turret type. Return this End Function ; ; free all memory used by a tank type. ; Function free_tank(tank.tankType) ; Free all the turrets. this.turretType = tank\turretList While this <> Null nextTurret.turretType = this\nextLink Delete this this = nextTurret Wend ; Free actual tank. Delete tank End Function ; ; Display settings of specified tank. ; Function print_tank(tank.tankType) Print "Tank Name : " + tank\tankName$ For n = 1 To tank\totalTurrets this.turretType = get_turret(tank, n) Print "Turret " + n + " : rotation=" + this\rotation + " elevation=" + this\elevation Next End Function Slenkar: I worked out how to do it by creating a type instance for each turret so they are destructible I'm a bit confused now - I thought you wanted to keep everything contained within a sigle type?! |
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I did this:for n=1 to number_of_tanks t.tank=new tank t\type =tank t\hull40 for x=1 to 5 t.tank=new tank t\type=turret next next |
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| thanx alot, big10p, for your efforts. The linked list thing is a big one! But can you also delete one of the turret-instances in the middle of the list. How should the list be updated then? |
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| lol, I knew you were going to ask for the ability to delete turrets - I toyed with the idea of including it originally. The reason I left it out is because it could lead to confusion, and here's why: Say you initially create a tank with 5 turrets. They will be numbered sequentially from 1 to 5 so that you can use the get_turret() function to access a specific turret. Fine and dandy but if you then delete turret number 3, say, all the turrets above it 'drop down' the list so: what was turret 4 is now turret 3, and what was turret 5 is now turret 4. Anyway, as long as you bear this in mind, here's the function to delete a turret: ; ; Delete a turret from the specified tank. ; Function delete_turret%(tank.tankType, turretNo%) ; Return -1 if turretNo is invalid. If (turretNo < 1) Or (turretNo > tank\totalTurrets) Then Return -1 ; Walk along turret linked list until we reach the requested turret. this.turretType = tank\turretList prev.turretType = Null For n = tank\totalTurrets-1 To turretNo Step -1 prev = this this = this\nextLink Next ; Remove turret from linked list. If prev <> Null prev\nextLink = this\nextLink Else tank\turretList = this\nextLink EndIf ; Free the turret type. Delete this ; Decrease the total count of turrets belonging to this tank. tank\totalTurrets = tank\totalTurrets - 1 Return tank\totalTurrets End Function |
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| wow, I find that extremely useful |
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