 | | | Re: What 's the particle shader? The answer...... | Re: What 's the particle shader? The answer...... 2004-07-31 - By patrick210hd
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I've posted a link to this before. If you want to know about the
particle shader, copy this and keep it for reference. Here it is
from Antoine. Patrick Tuten
Dear Dreamers,
It is definitely possible (and easy!) to shade particles in Carrara.
Each particle is seen by Carrara as an objects and therefore can
have
any kind of shader applied (but you can not apply a different shader
to each particle).
How to apply a shader to a particle system:
1- Drag and Drop a Particle Object in the scene
2- Modify the settings to get the Particle effect you want
3- While your Particle Object is selected, go to the shader Room
4- Edit the shader as usual
As you can see there is no difference between an Object and a
Particle Object in Carrara.
Here is a few tricks, I have found:
A)- Put a picture on your particles:
say you want to create leaves:
1- Do the previous steps
2- In the shader: open the picture of a leaf in the Color Channel.
3- You are done !
Carrara will apply the picture to each particle not to the global
object. It is good to know that each particle has its own little UV
space.
B)- Change the shape of particles
You are not satisfied with the offered particle shapes. No problem
do
your own particle shape !
1- Create your particle object as previously explained
2- Set the shape of the particles to Rectangle
3- In the Texture Room, create a Multi Channel Mixer, in Source 1
put
the shader you want, in Source 2 set all Channel to zero except
Transparency that should be at 100%, in the Blender put the shape of
the particle (other texture, image, ...).
This technic refers to the extented tutorial that I have posted on
the list about "Boolean Textures" or Alpha Channel VS Transparency.
The good news is that I have included in Carrara 1.0 an example of
this technic. Go to the Browser Tray (left of the screen), select
Shaders, scroll: in the Complex Procedurals section, you will find a
Boolean Shader.
The Boolean Shader shows how to create holes in objects, ie to
change
the shape of an object (or a particle in this example).
The thing to understand it that the Source 1 shader is the actual
shader of the object, Source 2 shader is the "hole" shader (or
transparent shader) and the Blender is where you define the shape.
Let say you want to create yellow star shape particles:
in Source 1, set color to yellow, leaves Source 2 as is (in fact
Source 2 should never be modified unless you want to create complex
special effects) and put in the mixer a grey levels image of a star
(created in a bitmap software).
C)Add motion blur to particles:
Very cool effect that can add a better speed feeling to your
particles.
1- Create whatever particle object with a the texture of your choice.
2- Create a Grey level image with a black to white gradient (the
gradient does not need to be linear: be creative !)
3- Edit the shader of the Particle Object, in Transparency Channel
load the previously created gradient. Rotate if needed the image.
D) Multiple shaders on Particle Object:
Impossible ? Nothing is impossible in Carrara ! ;-)
Let say you want a more complex animation of leaves with different
leaf shapes and colors.
1- Create a first Particle Object, apply previously explained
shading
technics.
2- Reduce the number of Particles
3- Duplicate the Particle Object, very slighly modify its settings.
4- Modify shading of the new Particle Object
5- Repeat step 3 to 4 several times.
You get a complex particle animation with various shapes and
textures.
C) Very usefull trick:
There is one tricky problem when shading particle: at the beginning
of the animation most of the time you don't see your particles. So
when you try to edit the shader you work blindly. A solution is to
change the time but when you modify the shader you create a bunch of
keyframes and end up with an animated shader (something you may not
want).
The trick is to stay at time equal zero, then go to the Texture Room
and switch the preview window to Flat Preview. This preview mode is
similar to one particle seen from the front.
D) The Mysterious Particle Shader !
If you go in the Texture Room, in the Channel Menu of any shader,
you
will find the Mysterious shader under: "Natural Functions>Particle
Shader".
This shader is extremely useful, its value is equal to the "life" of
a particle, ie zero when the particle is born and one when the
particle die (and a linear value between this two points). By itself
this function seems to be utterly uninteresting but if you apply
this
shader to a Blender things get very interesting instead ! By using
the Particle Shader you have the possibility to "retrieve" the life
information of each single particle (which is different) and modify
the shader accordingly.
A very simple example: say you want to create the sparks you see
flying away from a wood fire. Usually these sparks start with a
bright yellow and end with dark red.
In Carrara, simply create the Particle Object, edit the shader: set
color to black, put a mixer in the Glow Channel with Color 1 set to
Yellow, Color 2 to Dark Red, and in the Blender the Particle Shader.
Each particle will go independently from yellow to red.
As this email gets too long, I will stop here! I hope this few tips
and tricks on Carrara's particles will help you. By combining these
basic technics you can already create very intersting effects. The
next step is to combine the particles with outside effects such as
volumic primitives, Aura effet, ... but that is another story.
Happy rendering to all,
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