PYRO MECHANICS 101 DAY 1:�ATTRIBUTES OF FLAMES

PRESENTED BY WHISPY

WITH HIS LOVELY ASSISTANT STACK_MAN

WHAT ARE WE DOING TODAY?

• Who am I?
• Overview of the Program and this Lecture Series
• Quick History of Pyro
• Flamethrower Mechanics: Shaping Fire and its Behavior
• Flame Managers
• Flame Points
• Attributes of Fire

WHO IS WHISPY?

• 10-Year Pyro Player
• Highest Honors: Second Place Invite Highlander
• Background: Computer Engineering
• me like pyro and pyro number
• me lazy

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THE PYRO “PHD” PROGRAM

• Lectures on Saturday 2pm PDT, 1-4 weeks apart, depending on my life. Get subscribed for random dopamine spikes.
• 30 Minute Time limit per lecture, 30 minute live Q&A after class in Discord voice chat.
• If you want to help me with this project, join the Discord (linked below).

THE PYRO “PHD” PROGRAM

PYRO MECHANICS SERIES

• Emphasizing what is and isn’t possible (That we know of).
• Touch on practical and impractical tactics using these mechanics.
• Discussing what we do and do not know in as much detail as possible.
• Avoid judgements (unless entertaining), simply discuss what is true NOW.
• Save unlock and loadout discussions for future series, with some exception.

PYRO MECHANICS SERIES

• Flamethrower
• Weapon Timings
• Airblast
• Reflects
• And maybe some things that I’m forgetting.

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A BRIEF HISTORY OF PYRO TF2

JUNGLE INFERNO AND BLUE MOON

JUNGLE INFERNO (JI) AND BLUE MOON (BM)

• Arguably the most important updates to Pyro’s mechanics.
• Fixed many issues with flames, most importantly Flamethrower “Mojo” and Flame particle visuals.
• JI made flames TOO consistent.
• BM introduced Ramp-Up to address this.

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FLAME MODEL BASICS

• Flames are actually little floating cubes.
• They are fired about once every 0.044 seconds.
• Ammo is consumed about once every 0.08 seconds, or about 1 ammo per 2 points.
• They are 24 “hammer units” long on each side, about half the size of your projectile “collision hull”.
• They travel quickly at first, then quickly experience “drag”, slowing down to a halt at the end of their range.
• They collide with the world, and are generally very cute.

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FLAME “MODEL”: BEFORE AND AFTER JUNGLE INFERNO

Before: Flame Entities

After: Flame Managers and Flame Points

FLAME “MODEL”: BEFORE AND AFTER JUNGLE INFERNO

Before: Flame Entities

• Flames belong to a Flamethrower.
• Flame boxes act independently of one another.
• Each flame hits an individual target once and only once.
• Entities were not represented visually: instead an approximation was made.
• Despite the visuals colliding with the world, these entities simply passed through walls (and attempted to avoid dealing damage after doing so).
• Inherited ALL player momentum at time of creation.

After: Flame Managers and Flame Points

• Individual flames are now called Flame Points
• Flame Points no longer act fully independently: They act through a “Flame Manager”.
• Every Pyro with a “normal” Flamethrower has one Flame Manager.
• Flame Points do not deal damage individually: instead the Flame Manager decides when damage is dealt.
• The Flame Manager deals damage once every 0.075 seconds, as long as a target is colliding with at least ONE flame point.
• Damage dealt is based on the OLDEST flame point touching a target.
• Flame Points Inherit only a SPECIFIC PORTION of player momentum at time of creation.

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FLAME MANAGER ATTRIBUTES THAT CONTRIBUTE TO SHAPING FIRE

Utilized Attributes

• Spread Degree
• Flame Speed
• Flame Life Time
• Random Life Time Offset
• Flame Drag
• Flame Up
• Flame Ignore Player Velocity

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Unused Attributes

• Flame Gravity
• Start/end Size Multiplier
• Redirected Flame Size Multiplier
• Should “Reflect”
• Reflection Additional Lifetime
• Reflection Damage Reduction
• Max Flame Reflection Count

USED ATTRIBUTES DEMONSTRATION

FOR REALSIES

SPREAD DEGREE

• Controls the random vector added to each flame point’s velocity
• Units: Almost certainly degrees, but unconfirmed.
• Default Value of: 2.8
• Likely behavior: a random vector with a magnitude based on the value is added to each Flame Point upon its creation.
• Other possible behavior (possibly exhibited in Flame Entities): a vector is added to the position of flame entities. every game tick.

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FLAME SPEED

• Controls the initial magnitude of each Flame Point’s velocity.
• Units: Possibly Hammer Units per second.
• Default Value: 2450
• Fairly straightforward.

FLAME UP

• Controls the magnitude of the upwards pointing vector added to Flame Points position.
• Units: Possibly Hammer Units, Or Hammer Units per Second.
• Default Value: 50
• The Upwards Vector is likely applied on each game tick.

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FLAME DRAG

• Controls how quickly Flame Points slow down.
• Units: Unknown
• Default Value: 8.5
• More research is needed to discover the Drag formula used for the physics model.
• Thankfully, it’s probably safe to assume they were lazy and mostly copy-pasted the Flame Entity’s code for this, so we should be able to see it in the source code leak.
• Still, we cannot guarantee that the old code is exactly the same as the new code, so tests must be done to confirm that.

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LIFE TIME ATTRIBUTES

Flame Life Time

• Controls the “Base” lifetime of flames.
• Units: Seconds
• Default Value: 0.6

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Random Life Time Offset (RTLO)

• Controls the positive and negative “range” of possible life times of flames.
• Units: Seconds
• Default Value: 0.1
• Lifetime of flame point is decided on its creation:
• A random value between –RTLO and +RTLO is chosen to be added to the Life Time.
• Ex: 0.6 + (0.05) = 0.65
• Or: 0.6 – (0.1) = 0.5

FLAME IGNORE PLAYER VELOCITY

• Controls if Flame Points should ignore player velocity on creation.
• Units: None
• Default Value: 0
• By default, flames inherit the projection of the attacker’s velocity vector onto their aim vector.
• This allows us to disable that.
• Oddly, this is stored as a float rather than a Boolean. Maybe it’s a multiplier? More testing is required.

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UNUSED ATTRIBUTES DEMONSTRATION

FOR FUNSIES

FLAME GRAVITY

• Controls how much gravity should affect Flame Points.
• Units: Unknown.
• Default: 0
• This is probably not an inverse of Flame Up, as they would simply cancel out.
• One possibility is that this value multiplies a gravitational constant that is applied to Flame Points each game tick.

START AND END SIZE MULTIPLIERS

• Controls how large flames are relative to their “Base” size.
• One controls how large flames are at the beginning of their life, and other controls how large they are at the end of their life.
• Units: None
• Default Values: 1
• Incidentally, the size of flame points is controlled by a CVAR in the game. This is set to 12 by default, and controls the “RADIUS” of Flame Points.

REDIRECTED FLAME SIZE MULT

• Controls how much flames should grow or shrink after colliding with the world.
• Units: None
• Default Value: 1
• This multiplier applies after one collision, and does not stack if a flame collides with the world.

FLAME REFLECTIONS

• “ShouldReflect” enables and disables this feature.
• When enabled, flames bounce off the world in an “elastic” fashion.
• “The Angle of Reflection is Equal to the Angle of Incidence”.
• Reflect Additional Life Time controls how much faster or slower flames should die after reflecting.
• Reflect Damage Reduction controls how much more or less damage flames should deal after reflecting.
• Not sure if this stacks per bounce.
• Max Flame Reflection Count controls how many times flames should reflect off the world…. Maybe.
• Not sure if this is working correctly.
• This might control how many times the additional lifetime and damage reduction is applied.
• More testing required.

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FLAME MANAGER AND FLAME POINT MEMBER VARIABLES

Flame Manager Members

• Weapon
• Attacker
• Next Point Index
• TABLE: Point Spawn Times
• Player Map
• Last Valid Hit
• “Heat” value

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Flame Point

• Spawntime*
• Maximum Lifetime
• Velocity
• Number of “reflects”
• And some more.

HOMEWORK

• What properties did I change to make the funthrower?
• Go for a walk. Be sure to wear a mask, especially when going indoors.
• Your mask protects me, my mask protects you.
• Tell your loved ones that you love them.
• Hit up an old friend and check in on them.
• Remind yourself that you are valid.
• Black Lives Matter.

NEXT TIME…

• Blue Moon Damage Model?
• Give suggestions. Not set in stone just yet!