Quick Modding/Hacking Answers Thread

also Face.pbm can extend at least far enough down to be ridiculously large so that should not be a problem.

Are you implying I can have 203 face pics?

 

Are you implying I can have 203 face pics?

Yes. I believe you can.

 

You can extend tilesets and the facepics?
Damnit, I need to pay more attention to this forum.
Also, could somebody PLEASE help me change the icon?












And find a complete list of all the entities in cave story and what they are called...

 

You can extend tilesets and the facepics?
Damnit, I need to pay more attention to this forum.
Also, could somebody PLEASE help me change the icon?

And find a complete list of all the entities in cave story and what they are called...

Yes you can extend tilesets, but again, keep the width the same.

And you can find an almost complete list built into Cave Editor.

 

The CE I have has no entities named, excluding the later ones with random characters, and it also doesn't have any TSC notes built in either.



New problem:

How do I edit what Flag needs to be set for entitiy flags 4000/800 to work?

 

I have an assembly concept that I've been having trouble grasping for some reason: CDQ. I've read the definition (The cdq instruction sign extends the 32 bit value in eax to 64 bits and places the result in edx:eax by copying bit 31 of eax throughout bits 0..31 of edx) over and over, but I've never been able understand it. Help please?

 

I have an assembly concept that I've been having trouble grasping for some reason: CDQ. I've read the definition (The cdq instruction sign extends the 32 bit value in eax to 64 bits and places the result in edx:eax by copying bit 31 of eax throughout bits 0..31 of edx) over and over, but I've never been able understand it. Help please?

Basically it fills EDX with 00's, or if EAX is negative, with FF's. Then it can perform operations with the register EDX:EAX, which is like a bit 64 bit number. This is mostly used for the IDIV command, which divides EDX:EAX by whatever you put in IDIV, and stores it to EAX I think.

 

The CE I have has no entities named, excluding the later ones with random characters, and it also doesn't have any TSC notes built in either.



New problem:

How do I edit what Flag needs to be set for entitiy flags 4000/800 to work?

Question bump.

I also still can't edit the icon.

 

Thanks GIR.
The piece of code that I'm working with is a bit unusual though. It uses no IDIV after using the CDQ, instead it uses a SUB, and it's just a bit confusing.

I guess I'll figure it out eventually though.

 

Double post, but I have a question to answer.

As for the TSC information, they are on the right side of the script editor. Click on one of them to read the definition.

Spoiler

The entity list (I assume that this is what you mean) is right there (how the heck did you miss it?):

Spoiler

I ♥ MS Paint.

I'll look into the icon editing for you.

 

It uses no IDIV after using the CDQ, instead it uses a SUB, and it's just a bit confusing.

Normally whatever value that is in EAX will be positive, so I think the compiler often just uses CDQ as a quicker and easier way to fill EDX with 00's. Chances are the code after the CDQ uses EDX, right?

 

Yep, it does.
Here you go:

00406625  MOV DWORD PTR DS:[EDX+18],EAX   ;Change X velocity to EAX 
00406628  PUSH 4                          ;Maximum #.
0040662A  PUSH -4                         ;Minimum #.
0040662C  CALL 0040F350                   ;Call the Random # generator function (stores into EAX)
00406631  ADD ESP,8                       ;Fix the Stack.
00406634  SHL EAX,9                       ;Multiply EAX by 2^9
00406637  CDQ                             ;Extends the 32 bit value in eax to 64 bits and places the result in edx:eax
00406638  SUB EAX,EDX                     ;Subtracts EDX from EAX
0040663A  SAR EAX,1                       ;Divide EAX bu 2^1
0040663C  MOV ECX,DWORD PTR SS:[EBP+8]    ;Store the Weapon pointer into ECX
0040663F  MOV DWORD PTR DS:[ECX+1C],EAX   ;Change Y velocity to EAX

It's part of the Bubbler lvl. 3 Launch code that I was looking at a while back....

 

Yep, it does.
Here you go:

00406625  MOV DWORD PTR DS:[EDX+18],EAX   ;Change X velocity to EAX 
00406628  PUSH 4                          ;Maximum #.
0040662A  PUSH -4                         ;Minimum #.
0040662C  CALL 0040F350                   ;Call the Random # generator function (stores into EAX)
00406631  ADD ESP,8                       ;Fix the Stack.
00406634  SHL EAX,9                       ;Multiply EAX by 2^9
00406637  CDQ                             ;Extends the 32 bit value in eax to 64 bits and places the result in edx:eax
00406638  SUB EAX,EDX                     ;Subtracts EDX from EAX
0040663A  SAR EAX,1                       ;Divide EAX bu 2^1
0040663C  MOV ECX,DWORD PTR SS:[EBP+8]    ;Store the Weapon pointer into ECX
0040663F  MOV DWORD PTR DS:[ECX+1C],EAX   ;Change Y velocity to EAX

It's part of the Bubbler lvl. 3 Launch code that I was looking at a while back....

That is odd...

As far as I can tell though it won't change too much: Try removing the CDQ and sub eax, edx, and see if that does anything.

 

No noticeable change in behavior. Interesting.

 

Yep, it does.
Here you go:

00406625  MOV DWORD PTR DS:[EDX+18],EAX   ;Change X velocity to EAX 
00406628  PUSH 4                          ;Maximum #.
0040662A  PUSH -4                         ;Minimum #.
0040662C  CALL 0040F350                   ;Call the Random # generator function (stores into EAX)
00406631  ADD ESP,8                       ;Fix the Stack.
00406634  SHL EAX,9                       ;Multiply EAX by 2^9
00406637  CDQ                             ;Extends the 32 bit value in eax to 64 bits and places the result in edx:eax
00406638  SUB EAX,EDX                     ;Subtracts EDX from EAX
0040663A  SAR EAX,1                       ;Divide EAX bu 2^1
0040663C  MOV ECX,DWORD PTR SS:[EBP+8]    ;Store the Weapon pointer into ECX
0040663F  MOV DWORD PTR DS:[ECX+1C],EAX   ;Change Y velocity to EAX

It's part of the Bubbler lvl. 3 Launch code that I was looking at a while back....

Okay, so this is sign extension with CDQ:

If EAX is positive, executing CDQ will cause EDX to hold 0.
If EAX is negative, executing CDQ will cause EDX to hold FFFFFFFF (also known as -1).

The sequence of code:
CDQ
SUB EAX,EDX

Will add 1 to EAX (subtracting -1) if EAX was originally negative, and will do nothing if EAX was originally positive.

Considering that a difference of 1 is completely negligible in terms of velocity, this part of the code is totally pointless.

This:

PUSH 4
PUSH -4
CALL 0040F350                ;put random # into EAX
ADD ESP,8
SHL EAX,8                     ;multiply EAX by 2^8
MOV ECX,DWORD PTR SS:[EBP+8]
MOV DWORD PTR DS:[ECX+1C],EAX   ;Change Y velocity to EAX

Should do the same thing as:

00406628  PUSH 4
0040662A  PUSH -4
0040662C  CALL 0040F350
00406631  ADD ESP,8
00406634  SHL EAX,9
00406637  CDQ
00406638  SUB EAX,EDX
0040663A  SAR EAX,1
0040663C  MOV ECX,DWORD PTR SS:[EBP+8]
0040663F  MOV DWORD PTR DS:[ECX+1C],EAX   ;Change Y velocity to EAX

 

No noticeable change in behavior. Interesting.

I thought it might result in that, since if you were to run the 2 extreme ends of that code (eax being 4 or negative 4) the result on the eax that is moved into the y-velocity is rather negligible (if it's negative, it adds 1 to the y-velocity, which does close to nothing). Unless the edx is used a bit after (it probably just has the weapon pointer stored to it later), then it seems like a pointless bit of code. Might just be an artifact of the compiler :S

[Edit]: Carrotlord, why did you ninja me again? D:

 

Thank you for doing the calculations that I was too lazy to do Carrotlord (well, and GIR too).

On to the next part of the code!

 

I was tryign to make a new background for a throne room i was making, but it isnt working.I saved it as bkcast.pbm in the data folder. Cave editor displays it perfectly, but when i try to actually play it, the middle ground and foreground is displayed only. What am i doing wrong?

(Note that the files dimensions are multiples of 16)

 

I was tryign to make a new background for a throne room i was making, but it isnt working.I saved it as bkcast.pbm in the data folder. Cave editor displays it perfectly, but when i try to actually play it, the middle ground and foreground is displayed only. What am i doing wrong?

(Note that the files dimensions are multiples of 16)

CE was fucking up my bg's too. It only shows the bg during the fade-in.

 

Theres got to be a way though, as theres alot of hacks with great new backgrounds, yours included. It's probably something silly i'm doing. Liek at first i had placed the backgrounds in "level" folder, instead of "data".