Managing Internal Player States - GameCreators Forum

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anwserman

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Joined: 20th May 2011

Location: Wisconsin

Posted: 9th Aug 2011 13:23 Edited at: 9th Aug 2011 13:31

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This has been a problem that I've dreaded tackling, since everytime I do it, it always turns into a mess or some sort of spaghetti code. Basically, I don't know how to write a good character controller that I can extend.

If I start writing something, it'll typically break whenever I need to add a feature. But I'm trying to plan ahead now, but all I'm getting is fear of this code and a headache.

I've came up with the basic rules the player character needs to abide by. "Shift" rules modify the current state by some degree, whether be limiting features, modifying the playback animation, or both.

Shift-NormalMovementType
	0 = idle
	1 = walking
	2 = jogging
	3 = running
Shift-PanickedAnimation	
	TRUE if on fire, or being dragged down to the ground
	FALSE if else
Shift-InjuredAnimation
	TRUE if health < 25% maxHealth
	FALSE if else
Shift-TaggingInstant
	TRUE if in zone of a tag that only needs 1 hit to complete
	FALSE if else

Normal [Default state - on ground]
        Shift-PanickedAnimation
	Shift-InjuredAnimation
	Shift-MovementType
	(Ignore if panicked) Shift-TaggingInstant

Normal > Jumping [button press while on ground]
	Normal > Falling [no longer on ground]
	Normal > Falling Over [injured]
        Normal > Level Failed [level objectives missed or out of health, time, etc.]
        Normal > Level Complete [level objectives completed]
        (Ignore if panicked) Normal > Climbing [button press next to ladder]
	(Ignore if panicked) Normal >Tagging Normal [button press within graffiti zone]
Climbing
	Shift-TaggingInstant
	
	Climbing > Jumping [player jumped off of the ladder]
	Climbing > Falling Over [player injured while on ladder, falling off]
Jumping
	Shift-Panicked
        (Ignore if panicked) Shift-TaggingInstant

Jumping > Falling [player no longer travelling upwards]
        Jumping > Falling Over [player injured mid-air]
	Jumping > Drowning [player jumps into water]
	Jumping > Normal [player lands on ground]
	(Ignore if panicked) Jumping > Climbing [player grabs ladder in midair]
Falling	
	Shift-Panicked
	(Ignore if panicked) Shift-TaggingInstant

Falling > Normal [player lands on ground before injury occurs]
	Falling > Falling Over [player gets injured midair or is injured by ground impact]
	Falling > Drowning [falls into water]
        (Ignore if panicked) Falling > Climbing [latches onto ladder while falling]
TaggingNormal
	TaggingNormal > Jumping [jump to stop tagging]
	TaggingNormal > Falling Over [injured while tagging]
	TaggingNormal > Normal [tag is finished]
Drowning
	Drowning > Getting Up [player is placed outside of water and stands up]
Falling Over
	Shift-Injured

Falling Over > Drowning [player gets injured, flung off of a platform into water]
	Falling Over > Getting Up [player recovers from an injury on land and stands up]
Getting Up
	Shift-Injured

Getting Up > Normal [player stands up and resumes normal activities]
Level Failed
Level Complete

+ Code Snippet

Shift-NormalMovementType
	0 = idle
	1 = walking
	2 = jogging
	3 = running
Shift-PanickedAnimation	
	TRUE if on fire, or being dragged down to the ground
	FALSE if else
Shift-InjuredAnimation
	TRUE if health < 25% maxHealth
	FALSE if else
Shift-TaggingInstant
	TRUE if in zone of a tag that only needs 1 hit to complete
	FALSE if else

Normal [Default state - on ground]
        Shift-PanickedAnimation
	Shift-InjuredAnimation
	Shift-MovementType
	(Ignore if panicked) Shift-TaggingInstant

	Normal > Jumping [button press while on ground]
	Normal > Falling [no longer on ground]
	Normal > Falling Over [injured]
        Normal > Level Failed [level objectives missed or out of health, time, etc.]
        Normal > Level Complete [level objectives completed]
        (Ignore if panicked) Normal > Climbing [button press next to ladder]
	(Ignore if panicked) Normal >Tagging Normal [button press within graffiti zone]
Climbing
	Shift-TaggingInstant
	
	Climbing > Jumping [player jumped off of the ladder]
	Climbing > Falling Over [player injured while on ladder, falling off]
Jumping
	Shift-Panicked
        (Ignore if panicked) Shift-TaggingInstant

	Jumping > Falling [player no longer travelling upwards]
        Jumping > Falling Over [player injured mid-air]
	Jumping > Drowning [player jumps into water]
	Jumping > Normal [player lands on ground]
	(Ignore if panicked) Jumping > Climbing [player grabs ladder in midair]
Falling	
	Shift-Panicked
	(Ignore if panicked) Shift-TaggingInstant

	Falling > Normal [player lands on ground before injury occurs]
	Falling > Falling Over [player gets injured midair or is injured by ground impact]
	Falling > Drowning [falls into water]
        (Ignore if panicked) Falling > Climbing [latches onto ladder while falling]
TaggingNormal
	TaggingNormal > Jumping [jump to stop tagging]
	TaggingNormal > Falling Over [injured while tagging]
	TaggingNormal > Normal [tag is finished]
Drowning
	Drowning > Getting Up [player is placed outside of water and stands up]
Falling Over
	Shift-Injured

	Falling Over > Drowning [player gets injured, flung off of a platform into water]
	Falling Over > Getting Up [player recovers from an injury on land and stands up]
Getting Up
	Shift-Injured

	Getting Up > Normal [player stands up and resumes normal activities]
Level Failed
Level Complete

What would be the best way to implement a internal player state controller? I'm just looking at this overall and am overwhelmed. Any suggestions? Anyone else have any clever solutions or ideas for their character controllers?

Hi there. My name is Dug. I have just met you, and I love you.

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baxslash

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Joined: 26th Dec 2006

Location: Duffield

Posted: 9th Aug 2011 14:20 Edited at: 9th Aug 2011 14:22

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I tend to have a set of states just like this (for animation purposes at least).

I use constants for my player state IE:

+ Code Snippet

#constant player_walk 1
#constant player_stand 2
#constant player_run 3

I can set my player state like this:

+ Code Snippet

player_state = player_walk

...then I can run animations based on this:

+ Code Snippet

select player_state
    case 1
        rem Walking
        startframe=19
        endframe=29
    endcase
    case 2
        rem Standing
        startframe=38
        endframe=57
    endcase
    case 3
        rem Running
        startframe=86
        endframe=99
    endcase
endselect
frame=object frame(player)
inc frame
if frame>endframe or frame < startframe then frame=startframe
set object frame player, frame

Just written on the fly as an example, may contain nuts...

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anwserman

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Joined: 20th May 2011

Location: Wisconsin

Posted: 11th Aug 2011 14:30

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Ah, a simple example of a Finite State Machine =)
I researched it a bit, and that's basically what it is!

Thank you for the assistance.

Hi there. My name is Dug. I have just met you, and I love you.

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BatVink

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Joined: 4th Apr 2003

Location: Gods own County, UK

Posted: 11th Aug 2011 16:06

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anwserman, that code isn't a state machine, there is no code to change the states within the select routine. A state machine may be exactly what you need though, once you get your head around how they work. For now, I'd stick with the code baxslash has to get to working before you go more complex.

Baxslash I realise your code is just an example but you may like to know about one of IanM's commands that simplify it somewhat...

Value = WRAP( Current Value, Min Value, Max Value)

This code does all your frame wrapping for you

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baxslash

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Location: Duffield

Posted: 11th Aug 2011 16:13

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Quote: "This code does all your frame wrapping for you"

Yes I know that one thanks Batvink! I just find it easier to use native commands as much as possible on the forums as I get sick of saying "What do you mean you don't have it? Get the Matrix Utility plugin NOW!!"

I actually wrote a C# version of the wrap command with the same overloads at work because I couldn't easily find the equivalent... and for a bit of a diversion

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mr_d

DBPro Tool Maker

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Joined: 26th Mar 2007

Location: Somewhere In Australia

Posted: 11th Aug 2011 16:57 Edited at: 11th Aug 2011 16:58

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@baxslash
Also, because it seems we are picking on baxslash a little anyway

since you have already defined the constants, you can reuse them and get rid of the extra rem statements:

+ Code Snippet

select player_state
    case player_walk
        startframe=19
        endframe=29
    endcase
    case player_stand
        startframe=38
        endframe=57
    endcase
    case player_run
        startframe=86
        endframe=99
    endcase
endselect

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baxslash

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Joined: 26th Dec 2006

Location: Duffield

Posted: 11th Aug 2011 17:06

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Quote: "Also, because it seems we are picking on baxslash a little anyway"

Nobody's picking on me, they wouldn't risk the backlash. Anyway, my version is a little more obvious in terms of how the commands work (I think). It's not how I would necessarily code it in my own project.

Quote: "Ah, a simple example of a Finite State Machine =)
I researched it a bit, and that's basically what it is!"

Never heard it called that before but I do tend to think in terms of State or Mode when it comes to these kind of systems.

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DarkBASIC Professional Discussion / Managing Internal Player States