[4.5.9] Enabling support for the Strength/Defense System in your game!

[Kanbei85]

For reasons that remain a complete mystery, Joe and/or the devteam, such as it is, for NESmaker did not see fit to enable the use of the strength and defense system already present in the GUI. Out of the "box", NESmaker will only enable your weapon to do a single hitpoint of damage to any monster, and likewise a monster can only do a single HP of damage to the player.

Out of desperation, I began doing my own study, alongside Francois Brodeur. With his help, and by following a tiny bit of assembly tutorial, I have now got the str/def system working!

First, you will need to add two variables to the Zero Page RAM tab under Project settings: tempDE (for defense) and tempWD (for weapon damage).

Next, add Object_strength and Object_defense as Object Variables.

Last, you will need to add one variable under User Variables: myDefense. This is because I noticed that, for whatever reason, the player1_object variable "defense" value gets cleared to 0 if you die.

Now in your "script/Define Scripts/Subroutines/Create state" Add this between "STA Object_health,x" and "return bank". (Courtesy of Francois)

Code:
LDA ObjectStrengthDefense,y
AND #%11110000
ROR
ROR
ROR
ROR
STA Object_strength,x
LDA ObjectStrengthDefense,y
AND #%00001111
STA Object_defense,x

The result is now that strength and defense are available in the scripts to use as needed for objects (i.e. weapons and monsters). These also work for the player object, but as I said, for some reason they seem to get cleared when the player dies. This could probably be fixed in its own right, but I found it easier to use User Variables myHealth and myDefense instead.

I have gotten this to work for my game (WIP) now in both my Player Hurt and Monster Hurt scripts. I'll include the relevant bits below and you can adapt this to your own scripts as needed. What this does is a simple series of math equasion:
Strength - Defense = Damage

Health - Damage = Updated health

Player Hurt:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;DAMAGE SECTION

;DEC myHealth ;old Code from Joe, just decreases by 1 increment
;LDX player1_object ;This doesn't work because player1_object defense is getting set to 00 after a death
;LDA Object_defense,x
;STA tempDE ;Player Defense stat in tempDE
LDX otherObject ;Loading monster strength
LDA Object_strength,x
SEC ;Strength - player defense
SBC myDefense
STA tempWD ;Monster strength - player defense value set to tempWD
;LDX player1_object ;Loading player health to accumulator
;LDA Object_health,x
LDA myHealth
SEC
SBC tempWD
BMI +healthBelowZero
BEQ +healthBelowZero
JMP +notDeadYet
+healthBelowZero
JMP +playerHealthIsZero
+notDeadYet
;STA Object_health,x ;this would update the Player Object health stat, rather than the User Variable myHealth
STA myHealth
UpdateHudElement #$01 ;;Update HUD Hearts
ChangeActionStep player1_object, #$07 ;;Send player object into Action Step 07
PlaySound #sfx_GetHurt

Monster Hurt:

ChangeActionStep temp, #$07

LDX otherObject
LDA Object_defense,x
STA tempDE ;;tempDE is monster defense
LDX selfObject ;;now Player Weapon Object is in X register
LDA Object_strength,x ;;Weapon Strength is in Accumulator
SEC ;;Start Subtract
SBC tempDE ;; Monster Defense subtracted from Accumulator (Weapon Strength)
BMI +End ;;if the result is negative, then no damage happens, so end.
BEQ +End
STA tempWD ;;tempWD is player weapon damage after going through defense

LDX otherObject ;;Loading Monster Health
LDA Object_health,x
SEC ;;Subtracting Weapon Damage from Health
SBC tempWD
BEQ +killThisObject ;;if health is 0, kill
BMI +killThisObject ;;if health is negative, kill
STA Object_health,x ;;Save monster health
JMP +End
+End
JMP +doSkipKILLINGthisObject ;; Return

 

[Bucket Mouse]

You're awesome for figuring this out!

Maybe we can get weapons and armor (which would help make this relevant), the shop menus and other things like that working too. There are remnants of the code for them in the RPGBase folder...

 

[Kanbei85]

You're awesome for figuring this out!

Maybe we can get weapons and armor (which would help make this relevant), the shop menus and other things like that working too. There are remnants of the code for them in the RPGBase folder...

Well, if it's anything like the strength/defense situation, then the ability is just sitting there waiting to be enabled without much trouble.

 

[Kanbei85]

You're awesome for figuring this out!

Maybe we can get weapons and armor (which would help make this relevant), the shop menus and other things like that working too. There are remnants of the code for them in the RPGBase folder...

Did you notice ShopInfo.dat ?

 

[Bucket Mouse]

Did you notice ShopInfo.dat ?

What is it for? It doesn't seem to be loading into any of the banks, and it doesn't correspond to anything in the GUI.
Something called NT_Shop is loaded into Bank 1E, but it's kind of a mess:

                                     õõõ                           õìáèé                           õõõõõ                                                                                        õ                               õõõõõõõõ

That's what it looks like.

Bank 16 has NT_Shop listed among a few other things that aren't used:

NameTablePointers:
    .dw NT_StartScreen, NT_Register, NT_SongBook, NT_Death, NT_Menu, NT_NPC, NT_Shop, NT_Hud, NT_Win, NT_Story

I'm not sure where to begin with that.

 

[Retrofaija]

Thanks for this! It's great how many bits and pieces of diamond solid info you find on the forums just by digging around. Works like a charm this one!

 

[CashThulhu]

This is great! Finally registered on the forum to say thanks for this. I was banging my head on it for a while before finding this post.

 

[Lord_Klump_Of_Kongo_Bongo]

holle crap this tutorial is great! It'll make making my units in my strategy game a LOT easier to give stats

 

[tbizzle]

Works like a charm!!!!! Thank you!!!!!!!!!!!!!!

 

[tbizzle]

I was at 273 bytes within my Object Variables. I noticed I had plenty of room in my Overflow Variables (224 bytes). So I put Object_strength and Object_defense in my Overflow Variables and gave them 13 bytes each. Everything appears to be working just the same as when they were placed in Object Variables. If anyone needs space in their Object Variables, moving these two variables to the Overflow Variables so far appears to be a good space saver!

 

[SciNEStist]

A safer bet would be just to reduce your max objects. 13 objects is already too much for nesmaker to handle at once.

 

[tbizzle]

A safer bet would be just to reduce your max objects. 13 objects is already too much for nesmaker to handle at once.

What would be a good number to set it to???

 

[SciNEStist]

It all depends on your game. you have to think about the maximium amount of objects that could be onscreen at any given time. any less, and you could cause some major issues, or prevent new objects from spawning. as long as your are under about 250, you should be fine.

non scrolling games are easier to figure because you have 4 placeable objects and the player. if any objects get created by them (like melee objects or projectiles), you would also count those. scrolling games preload the left half of the next screen, so you would also have to count those.

I usually drop it down to about 10