= How to |> make clouds =

== Create clouds using volumes ==

* Create a geometry object.

* Append an [IsoOffset|Node:sop/isooffset] node at the geometry level.
    Make sure you set the __Output Type__ to __SDF Volume__, and the __Invert Sign__ checkbox is turned on. Increasing the __Sampling Divs__ provides better quality in more detailed volumes.
    
* Append a [Volume Mix|Node:sop/volumemix] node.
    Change the __Mix Method__ to __User__ so that you can enter your own expression as the __Value__. For example, `clamp($V*10, 0, 1)`.
    
* Set up [lights and a camera|/shelf/lightsandcameras].
    If you want shadows, set the __Shadow Type__ parameter on your light node to __Depth Map Shadows__. Using depth map shadows is much faster than ray traced shadows.
    
* Use one of the volume materials on the [Material Palette|/ref/panes/materialpalette].
    
    * [Billowy Smoke|/gallery/shop/material/billowy_smoke]
    * [Wispy Smoke|/gallery/shop/material/wispy_smoke]
    * [Basic Smoke|/gallery/shop/material/basic_smoke] 
    
    TIP: 
        Billowy Smoke is useful because it has noise parameters.
                
    NOTE:
        You cannot drag and drop this material in the viewport like you can for other materials. You must point to it on the __Material__ tab of the object.

* You can also create an [Instance Object|Node:OBJ/instance] to instance your original geometry onto several points. 

    For example, inside the instance object you could create a [grid|Node:sop/grid] and append a [scatter|Node:sop/scatter] node. On the __Instance__ tab of the [Instance Object|Node:OBJ/instance], make sure you turn on the __Point Instancing__ checkbox, and point to your object in the __Instance Object__ parameter.
    
== Creating clouds using i3ds ==

* Create an array of still [particles|/particles] to represent a cloud.

* Create a [metacloud|Node:shop/v_metacloud] shader in the [Icon:NETWORKS/shop] SHOP network.

* In the [Icon:NETWORKS/rop] Output network, create a [3D Texture Generator|Node:out/image3d] to drive the image3d program that generates 3D texture maps.

    On this node, set the following parameters:
        
    * __Output Image__ - to where you would like to output your .i3d files
    * __SHOP__ - to your metacloud
    * __Render As__ - to __Raw point geometry__
    * __SOP__ - to the particle array
    * Turn on the __Verbose__ checkbox
        
    Click the __Render__ button.
    
* Return to the [Icon:NETWORKS/shop] SHOP network and create a [Mantra: Image 3D Volume Procedural|Node:/shop/vm_geo_image3dvolume] and set the __I3D File__ parameter to the .i3d file that was just created.

* At the [Icon:NETWORKS/OBJ] object level, create a geometry object and apply a [Billowy Smoke|/gallery/shop/material/billowy_smoke] material. On the __Geometry__ sub-tab of the __Render__ tab on the object, set the __Procedural Shader__ to the __Image 3D Volume Procedural__ shader, which will render the .i3d file directly.
    
[Image:/images/howto/clouds.png]

=== Tips ===

* The __Volume Step Size__ parameter on the Mantra node controls the level of detail in volumetric clouds. The lower the step size, the greater the detail.

* Using shadows will make your cloud look more realistic. Set the __Shadow Type__ to __Ray-Traced Shadows__ on the __Shadows__ tab of your light node.