Posted: 5/13/2008 10:24 PM
Post subject: Hit box viewing?
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Pekopon
Former player
Joined: 10/6/2007
Posts: 330
Location: B.C Canada
I was wondering if there is a way to see an object's hit box in visualboy advance 19.3. I have a theory about a certain glitch, but I'm not positive. My assumption depends on viewing my character's hit box. The glitch goes like this. In Lady Sia, there are platforms that you normally can't reach, or can't get to before they go away. However, by swinging your sword at the right time, you are able to get on them. My theory is that Sia's Hit Box gets slightly larger while swinging her sword, which in return makes the platforms accessible. If there is a way to confirm this, I'd like to know. Also, there are some invisible platforms in level one that I discovered a long time ago that were probably left in there due to sloppy programming. If there is a way to see platforms in a debug or something, that would be great too. There may be more invisible platforms in the game. Lady Sia is actually a pretty buggy game. There's a lot of strange stuff that happens when a certain glitch is performed.
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Posted: 5/13/2008 11:05 PM
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alden
Player (120)
Joined: 2/11/2007
Posts: 1522
There's no "automagic" way to display hit boxes in any emulator -- in fact, the "hit box" is not usually directly stored as one "object" in the game's RAM, but rather is generally a collection of values for the various "sides" of it. Even when you do find the info in RAM, there's no built in way of drawing to the screen in VBA (yet! Lua please somebody? or tell me how to do it myself :P ?) But, you could use memory watch to monitor the hit boxes. Here's a page about memory watch with some hints on how to get started (it's not a full fledged tutorial...yet): http://tasvideos.org/MemorySearch.html
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Posted: 5/14/2008 10:58 AM
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Warp
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Joined: 3/10/2004
Posts: 7698
Location: Finland
I bet that in the vast majority of cases "hit boxes" are implemented in games as program code (in the form of a bunch of conditionals). This means that there is absolutely no way to automatically know what a certain game is using as "hit box" (or if it's using a completely different technique altogether), and even on a game-by-game basis you would need to disassemble and study the code to try to find the hit box checking routine in order to see how it's done. I suppose that with many or even most games, once you have disassembled the hitbox checking routine and you know how it does it, you could write a lua script or whatever which does the same thing and shows the hitbox on screen, but I bet it's usually quite a lot of work to get there.
Posted: 5/14/2008 2:42 PM
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P.JBoy
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Well in Metroid Fusion and Metroid Zero Mission there are specific RAM addresses for the vertical and horizontal size of Samus' hitbox and where the centre [or top, I haven't looked into it] of the hitbox is in relation to Samus' position as a horizontal and vertical offset. And I didn't even need to do any debugging or disassembling to find it
Posted: 5/14/2008 5:55 PM
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nitsujrehtona
Joined: 3/17/2007
Posts: 97
Location: Berkeley, CA
Gradius 3, on the other hand, was exactly as hard as Warp made it sound. But part of the problem was that the player's hitbox didn't vary in that game. In most platformers it's probably feasible to find your own hitbox with cheat search, and then convince the emulator to trace through the game and flag relevant subtract/compare instructions...
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Posted: 5/16/2008 3:15 PM
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Comicalflop
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I don't see what's so hard with this request in making VBA visually show the hitboxes. It certainly looks doable as Upthorn shows.
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Posted: 5/16/2008 3:18 PM
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moozooh
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Joined: 8/4/2005
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What Upthorn did was made on a per-game basis. While he has been working on a universal hitbox display, it's obvious it will still not be applicable to all games since they track hitboxes differently, or have multiple hitboxes per player character.
Warp wrote:
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Posted: 5/16/2008 9:35 PM
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Comicalflop
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You'll notice Pekopon was making one game request as well, not something universal. Meh.
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