Changes between Version 1 and Version 2 of ParticleFormat

Timestamp:

Apr 9, 2011, 3:01:01 PM (13 years ago)

Author:

Philip Taylor

Comment:

more particle details

ParticleFormat

@@ -51 +51 @@
   The RGB colour of the texture is drawn over the background, with transparency determined by the alpha channel. This is useful for more solid-looking particles, but may introduce visible glitches when particles are drawn over nearer particles, so it should be tested carefully from all angles.
 
+== Parameters ==
+
 The main part of the effect file is specifying '''initial particle parameters'''. Every time a new particle is created by the particle emitter, its state is determined by these parameters.
 
@@ -68 +70 @@
  * '''`color.g`'''
  * '''`color.b`'''
+
+Each parameter can be specified in a number of ways:
+ * '''`<constant name=`"'''''parameter'''''`" value="`'''''number'''''`"/>`''' - the parameter will always have the given value.
+ * '''`<uniform name=`"'''''parameter'''''`" min="`'''''number'''''`" max="`'''''number'''''`"/>`''' - the parameter will be given a random value between min and max. Every value in that range is equally likely (hence the "uniform"). Max must be greater than min.
+ * '''`<copy name=`"'''''parameter'''''`" from="`'''''parameter'''''`"/>`''' - the parameter's value will be copied from the value of some other parameter. This lets you do randomised greyscale colours - use a `uniform` for `color.r` so that it's given a random value, then use some `copy` so that `color.g` and `color.b` are given the ''same'' random value as `color.r`. The 'from' parameter must have been computed first (i.e. be higher up in the parameter list from earlier in this section - `color.g` can copy from `color.r`, but can't copy from `color.b` since that's computed later).
+ * '''`<expr name=`"'''''parameter'''''`" `'''''...'''''`"/>`''' - a hopefully-temporary inflexible hack to make construction dust scale with the number of workers. You probably shouldn't use this.
+
+Each parameter has a sensible default value, so you don't need to explicitly specify them all. E.g. you can omit all the `position` parameters if the particles should just be emitted directly from the emitter point instead of being spread randomly over a larger volume.
+
+== Effectors ==
+
+Once a particle has been emitted, it will move and spin according to its velocity, and it will automatically fade in and out. You can add more complex motion with '''particle effectors'''.
+
+Currently they're very limited so the only thing you can do is:
+ * '''`<force x=`"'''''number'''''`" y=`"'''''number'''''`" z=`"'''''number'''''`"/>`''' - each particle will be subjected to a constant acceleration force (in metres per second per second) in each direction. Each attribute will default to 0, so typically you can just write e.g. `<force y="-2.5"/>` to get downwards acceleration (simulating gravity).