Using Textures

A texture adds realism to a rendered image, because it is an objects “Id” and we can recognize specific properties of this object just by evaluating the surface texture: metal, wood, plastic, stone... Another method of describing surface is the use of shaders. They simulate the physical characteristics of an object's surface or its “inner life”, for example volumetric or SSS shaders. RealFlow supports both types – textures and shaders, but the latter one is only available with the integrated Maxwell Render engine. Here, we want to talk about textures exclusively.

Objects with proper UV coordinates.

Before we start you should know a few things about textures in RealFlow:

• Theoretically, it is possible to use any kind of texture in RealFlow as long as the map's image format is supported. Valid formats are JPG, PNG, TIF, and TGA.

• There is one important restriction: it is not possible to stack different property maps to create complex surface definitions. You can only apply one texture map, and RealFlow does not care whether it is a bump or a specular map, for example. All maps are treated like diffuse textures.

• Imported objects require UVW coordinates to make textures work correctly. It is not possible inside RealFlow to manipulate UVW grids and this has to be done inside your 3D application. So, if your UVWs are broken inside your 3D program then they will broken inside RealFlow as well. RealFlow will just show what it gets.

• RealFlow provides several texture types, for example wetmaps, foam maps, friction, or roughness maps. All these different maps can be visualized in the viewport, but only one at a time. You cannot mix wetmaps with an object's diffuse map, or friction with sticky maps.

• Property maps (particle friction, roughness, sticky etc.) also support image sequences. This way it is possible to apply changes over time.

• The object's “Display” panel provides a drop-down menu where you can choose which map type you want to show.

Object Textures

This type does not need any particular requirements, except proper UVW coordinates. Some exchange plugins even preserve the path to the object's texture and write it to the export file. This way you have direct access to it without having to search for the texture in RealFlow:

• Switch to RealFlow's “Flat Shading” or “Smooth Shading” mode with 9 or 0 key.

• Select the object and go to Node Params > Texture > Load Texture

• If the field is empty click on the hyphen to open a file browser.

• Choose the object's texture and confirm with “OK”.

• To finally show the texture, choose Node Params > Display > Texture > Object

• This short workflow has to be repeated for every object you want to display textured.

Wetmaps (WetDry Maps)

The creation of wetmaps (also called WetDry maps) is explained in a separate tutorial. Please follow this link to get there: “Wetmap Creation”

Property Maps

This topic includes a wide variety of different maps for:

• Particle friction

• Collision tolerance

• Grid friction

• Sticky

• Roughness

• Bounce

Please bear in mind that you will only have access to these parameters when there is at least one particle emitter or Hybrido domain in your scene.

The corresponding parameters are located under

Node Params > Particle Fluid Interaction

“Grid friction” is only available in combination with Hybrido domains and can be found here

Node Params > Grid Fluid Interaction

The parameters, supporting images maps, carry a small chess board icon. To add an image or a sequence of maps, right-click on the parameter's name and choose “Load texture”. All adjustments are made from the appearing window. A complete description of the parameters provided can be found under:

Objects – Particle Fluid Interaction > Mapped Parameters

Using Property Maps

A very nice application for this map type is the simulation of different surface properties, for example friction. Let's assume you want to create a small river. When you go outside and visit a stream in nature you will see many different materials in and around the brook bed. There can be soil, gravel, stone or clay. All these materials have completely different friction properties. At the stream's bank, friction is normally higher, because there are also often tree roots, slides of soil or plants decelerating the water. The brook bed, on the other hand, normally contains smoothed gravel and is free from plant material – the water can flow without too much resistance. But, there are also zones with sand or obstacles like branches.

All these different situations can be mimicked with a single map. Model a river bed and create proper UV coordinates. Then, paint a map with different shades of grey to define zones of higher and lower friction. Dark areas indicate areas with low friction, bright tones represent high values. The file should be stored with RGB colours.

Apply this texture to the model of the river and export the geometry to RealFlow. There, import the river model and follow these steps:

• Go to the object's Node Params > Particle Fluid Interaction > Particle friction

• Right-click on parameter's name > Load Texture

• RealFlow opens a new window called “Load Texture for Parameter”.

• Fill out the dialogue and confirm your settings with “OK”.

If the maps is not visible, please follow the steps described above under “Property Maps”. A complete description of the “Load Texture for Parameter” window's parameters can be found here under "Mapped Parameter".