Example:
r_part blah
{
	texture textures/particles/myimage.tga
	tcoords 0 0 64 64 64
	die 2
	scalefactor 1
	scale 20
	alpha 0.5
	rgb 255 0 0
	rgbdelta 0 128 128
	spawnmode ball
	spawnorg 32
}

will give transparent (0.5) red particles that will fade to fully white when they go fully transparent 2 seconds later.
they will spawn within a ball of 32 units radius.


Types:
Always try to include a type. The engine will guess what your particle is meant to be otherwise, based on textures and other nonsense. That stuff is generally unreliable, and probably not what you want.

Chaining:
You can add multiple particle descriptions to a single effect. The first should be 'r_part foo', and the others should be 'r_part +foo'. Particles without a + will reset the chain.

Effect naming:
Effects loaded by r_particledesc will be given an internal prefix, eg: foo.cfg.
If the gamecode explicitly states foo.bar, your foo.cfg will automatically be executed, and will automatically use the bar effect from it.
The effect can still be overriden from a custom config by explicitly naming the effect foo.bar - the effect bar in the config foo will not override this, but would override bar on its own.

Scale:
scale values are defined in 1/4th qu, for some reason.
scalefactor typically needs to be explicitly set to 1. this value affects how the particle scales with distance from view, rather than the actual size of the particle.



texture <TEXTURENAME>
	specifies to use an image named TEXTURENAME for this effect.

tcoords <s1> <t1> <s2> <t2> [tscale] [rsmax] [rsstep]
	specifies to use a subsection of the image.
	if tscale is set, all units are divided by this. it is the virtual size of your texture. So a value of 1 means that your texture coords must be between 0 and 1. But if it properly matches your texture's size, the coords are in pixels.
	if rsmax is present, each particle will use a random image. These images must be on a single row in your particle font.
	rsstep specifies the stride (gap from one to the next) in your particle font, and is only needed if rsmax is present and greater than 1.

rotationstart <min> [max]
	the particle will start with a rotation rotated between min and max.
	if max is missing, the particle will always start with the min value.

beamtexstep <value>
	only valid if the effect is a beam.
	specifies the number of quake units per beam texture repitition.

beamtexspeed <value>
	only valid if the effect is a beam.
	controls how fast the texture scrolls on the beam.

scale <min> [max]
	particles will start with a diameter of this many quake units.
	actual scale will be randomly chosen between min and max (max defaults to equal if min is missing)

scalerand <extra>
	obsolete
	overrides the scale max value
	actual scale will be now be randomly chosen between min and min+extra

scalefactor <frac>
	controls how the particle scales with distance.
	1 makes the particle scale the same as anything else
	0 makes the particle not change size no matter how far it is

scaledelta <value>
	controls how the particle scales over time
	specifies the change in the particle scale per second.

step <min> <max>
	trails/beams only
	specifies the distance between each particle in the trail (or beam).

count <min> <max>
	point/box effects only (not trails or beams)
	specifies how many particles are spawned per effect (some classic effects contain an extra scaler which is multiplied by the resulting value)

alpha <value>
	specifies the initial alpha value of the effect

alphadelta <value>
	specifies how much the alpha value of the effect changes per second (subtracted)

die <maximum age> <minimum age>
	specifies the maximum age of the particle

diesubrand <value>
	obsolete (set by die)
	specifies the maximum starting age of the particle.
	basically the particle will live up to this much less time. the alpha value will also be aged by the amount chosen by this value

randomvel <horiz> [vert]
	controls how fast the particle moves when it spawns. This works regardless of any requested velocities.
	if vert is not specified, horiz is used instead.

veladd <value>
	controls how much of the effect's spawn velocity is used, can be greater than 1, or negative.

orgadd <value>
	biases how much to add to the starting origin relative to the requested velocity.

friction <<xyz>|<xy> <z> | <x> <y> <z>>
	Proportion of the particle's speed that should be lost from friction. Negative values are accepted.

gravity <value>
	amount that the particle's velocity changes per second, in quake units.

clipbounce <value>
	how much of the particle's velocity to use if the particle is clipped. See cliptype.
	Defaults to 0.8

cliptype <effectname>
	Specifies which new effect to spawn when the particle hits something.
	The origin and velocity of the particle are used to spawn the new effect.
	The clipbounce value is used as a scaler for the reflected velocity.
	If the effect named is the effect itself, the particle will merely bounce, instead of spawning a new effect.
	FIXME: make default to bounce if clipbounce is set without cliptype.

clipcount <count>
	The scaler to use for the number of particles to spawn upon a clip event.
	Only valid in conjunction with cliptype.

assoc <effectname>
	Specifies another effect to spawn at the same time that this effect is spawned.
	Thus allowing two sets of particles from one effect.

inwater <effectname>
	obsolete
	Specifies a replacement effect to use when this one is spawned underwater.
	assoc used is the replacement effect. the assoc value from the replaced effect is ignored (this includes +foo chains).

overwater [content names]
	Specifies that this particle should ONLY be spawned when out of water.
	The particle will not spawn under water (this does not affect assoc chains).
	Content names are a space-separated list of: water slime lava sky solid fluid. Default is fluid if not specified.
	The r_part_contentswitch cvar must be enabled for this to function correctly.

underwater [content names]
	Specifies that this particle should ONLY be spawned when underwater.
	The particle will not spawn if the spawn position is non-water (this does not affect assoc chains).

colorindex <index> [rand]
	Specifies a palette index to spawn the particle with.
	The index used is between index and index+rand.
	overrides the normal starting colours.

colorrand <rand>
	obsolete.
	replaces the [rand] part of the colorindex setting.

citracer
	only valid if colorindex is set.
	adds a palette index between 0 and 3, based on the particle index in the effect or trail.

red <value>
green <value>
blue <value>
rgb <red> <green> <blue>
rgb <value>
	Specifies the initial red, green, and/or blue values for each particle.
	Fully opaque is 255 or above.
	Values above 255 are valid, but will remain opaque until the value drops below 255 from the colour deltas.

redrand <value>
greenrand <value>
bluerand <value>
rgbrand <red> <green> <blue>
rgbrand <value>
	Specifies how much extra red, green, and/or blue there may be for particles.
	The initial colour will be multiplied by this amount before addition.
	Each componant is separately randomized. EG, red might  add nothing, while the full green is added, and only half the blue.
	Fully opaque is 255 or above.

redrandsync <value>
greenrandsync <value>
bluerandsync <value>
rgbrandsync <red> <green> <blue>
rgbrandsync <value>
	Specifies how much extra red, green, and/or blue there may be for particles.
	The initial colour will be multiplied by this amount before addition.
	Componants are syncronised. EG, if the full amount of red is added, the full amount of green and blue will also be added.
	Fully opaque is 255 or above.

reddelta <value>
greendelta <value>
bluedelta <value>
rgbdelta <red> <green> <blue>
rgbdelta <value>
	Specifies how much the red, green, and/or blue values of each particle change over time.
	The value 255 is the value required to go from opaque to invisible in 1 second.

rgbdeltatime <value>
	Specifies for how long the particle may change colours for. After this many seconds, the particle may no longer change colours (delta becomes 0).

rampmode <mode>
	mode may be one of:
	none: uses rgb+rand+sync+delta+scale+scaledelta values.
	absolute: the ramp overrides all colour+scale values. The effect moves from one absolute ramp index to the next.
	delta: uses rgb+rand+sync+scale, but not delta values. All delta values come from the colour ramp instead.

	if not none, the ramp index used is based upon the particle's age, its lifetime, and how many ramp elements there are.

rampindexlist <idx1> [<idx2> [idx3 ...]]
	Scale used is the currently set scale value.
	Specifies a set of palette index values to use for the effect as part of the effect's colour ramp.

rampindex <idx> <scale>
	Specifies an individual palette index value and particle scale to use for the effect as part of the effect's colour ramp

ramp <red> <green> <blue> [alpha] [scale]
	Specifies a ramp index in rgb terms, regardless of palette.

stains <value>
	How much the effect discolours the wall upon impact.
	The stained colour is based upon the colour of the particle upon impact.

blend <mode>
	mode may be one of: add, subtract, blendcolour/blendcolor, blend
	if the texture used is actually a shader, this is ignored.

spawnmode <mode> [arg1] [arg2]
	This affects how particles are positioned when they first spawn, and their initial velocities.
	for point effects, mode may be one of:
		box: simple axially aligned box of particles.
		circle: particles spawn within a ball with uniform distance from the center. none will appear in the middle.
			arg1: percentage of the circle to cover. a value of 5 will go around the circle 5 separate times. this can be used for weird beam effects.
			areaspread: the radius of the ball
			areaspreadvert: the height of the ball. if 0, will be a flat circle
		ball: particles spawn randomly within a ball.
			areaspread: the radius of the ball
			areaspreadvert: the height of the ball. if 0, will be a flat circle.
		telebox: matches quake's telebox
		lavasplash: like chthon's lava splash
		uniformcircle: particles are spawned in a circle with uniform distance between and from the center. z=0.
		syncfield: particles spawn at predictable locations based upon time within a rough sphere. Only useful for effects that are regenerated+replaced every frame.
		distball:
		*default*: regular box. particles are spawned inside an axially aligned box.

	for trail effects, mode may be one of:
		spiral: particles are given velocities perpendicular to the direction based on the distance moved.
		tracer: particles spawn with alternating horizontal velocities (a wake effect).
		*default*: particles spawn as a regular trail.

spawnparam1 <value>
	obsolete. see spawnmode.

spawnparam2 <value>
	obsolete. see spawnmode.

up <value>
	the particle's starting origin is moved upwards by this amount (worldspace).

type <mode>
	How the particles look.
	mode may be:
		beam: valid only for trails. Particles form a single textured beam acting as nodes along it.
		spark: particles are lines, their length depending upon their speed.
		sparkfan: particles are non-planar triangle fans, their length depending upon their speed.
		texturedspark: textured particles are aligned along their direction of movement, their length depending upon their speed, width equal to their scale.
		cdecal/decal: particles are spawned only upon bsp geometry. They are clipped by it.
		udecal: unclipped decal. exact semantics are subject to change.
		*default*: Particles are regular, rotating, 2d images.

isbeam
	obsolete.
	please use 'type beam' instead.

spawntime <value>
spawnchance <value>


emit <effectname>
	Specifies the effect to periodically emit.

emitinterval <min>
	Particles will not emit additional effects for this duration after emitting one.

emitintervalrand <extra>
	FIXME: fold into emitinterval
	

emitstart <seconds>
	Prevents the particle from emitting anything for this duration when it first spawns.

spawnorg <horiz> [vert]
spawnvel <horiz> [vert]
	obsolete

viewspace [frac]
	Specifies that this particle type should move relative to the camera.
	Not compatible with splitscreen.
	Should not normally be used in combination with clipping/bouncing.

perframe
	apply inverse frametime to count (causes emits to be per frame).

averageout
	average trail points from start to end, useful with t_lightning, etc

nostate
	Causes the particle system to ignore all state information.

nospreadfirst
	don't randomize org/vel for first generated particle

nospreadlast
	don't randomize org/vel for last generated particle

sound <soundname> <vol> <attenuation> [pitch] [delay]
	When the effect is first spawned, the named sound will play with the given volume and attenuation at the center point. This may not work with all spawn methods, as it will ignore any count scales.

lightradius <radius>
lightradiusfade <radiuspersecond>
lightrgb <r> <g> <b>
lightrgbfade <r/s> <g/s> <b/s>
lighttime <maxage>
	Spawns a dlight when the effect is spawned.
	dlight is removed when radius drops to 0 or the age is exceeded.
	at this time it is not possible to override the corona/specular levels.

lightcubemap <cubemapnum>
	value 0 means no cubemap.
	otherwise with eg cubemap 5, uses image files cubemaps/5ft.tga, cubemaps/5bk.tga, etc.
	fixme: at the current time, the cubemap is world-aligned and cannot rotate.

model <name> <firstframe> <endframe> <framerate> <alpha>
	spawns sprites or models that fly away with random angles and run through some frame sequence. handy for simple gib effects.

spawnstain <radius> <r> <g> <b>