volume_cloud_base

A volume_cloud_base material is used to create clouds or shaped fog. It is applied to Volume boxes.

In the States tab you can set rendering passes and available options. Enabling some of the states activates additional textures and parameters in the Textures and Parameters tabs respectively.

For this material the states contain only Options field.

Possible values for a Samples option:

All the other options can be either enabled or disabled by ticking the respective boxes.

All the states can be set to default ones - click a Set to parent button near the state (if the state is different from the default one, its field will be highlighted with green).

The states available for this kind of materials are listed below.

Options

The following options are set in the Options field of the States tab.

GUI name	XML name	Description
Samples	samples	Defines how many times a density texture is sampled to render a cloud. The higher the value, the smoother and less discrete the cloud is. To increase the performance, use low Samples values. Samples = 32 Samples = 128
Attenuation	attenuation	Specifies if the attenuation texture will be used to override transparency values with the texture color for the cloud.
Volume	volume	Specifies if a density texture is a 3D texture (rather than a 2D one).

In the Textures tab of the Materials Editor you can:

• Load the textures - click a Load button near the texture and specify the path to the texture or type the path in the texture field manually
• Open the view window to see texture's details - click a View button near the texture
• Set the current texture to default one - click a Set to parent button near the texture (if the texture is different from the default one, its field will be highlighted with green)

The textures available for this kind of materials are listed below.

Base Textures

Base textures are loaded and modified in the Base field of the Textures tab.

GUI name	XML name	Description	Channels
Density	density	Specifies the shape of the cloud and its density: 3D Texture is used by default (if the Volume option enabled in the States tab). It represents a set of vertical cross-sections of the cloud. 2D Texture is used if the Volume option in the States tab is disabled. It represents one horizontal cross-section of the cloud.	RG: If Attenuation option is disabled in theStates tab: R value specifies the actual grayscale color G value is used for transparency (alpha) values: 0 is full transparency 1 is full opacity If Attenuation option is enabled in theStates tab: : R value specifies the U coordinate of the attenuation texture: The minimum value of 0 means U coordinate value is 0 The maximum value of 255 means a U coordinate value is 1 U coordinate of the attenuation texture. G value is ignored. Alpha values are specified in the attenuation texture instead
Attenuation	attenuation	Attenuation map. A texture to add the color to the cloud ans specify its transparency.	RGBA: RGB values store the color of the texture A (alpha) value stores transparency values. G channel values of the density texture are ignored Grayscale attenuation texture Colored attenuation texture

In the Parameters tab you can set or modify base and additional parameters.

Parameters of different types are set in different ways:

• expression - vector values can be set either in the field near the parameter or in the dialog window opened when double clicking this field
• slider - the value can be set either by smoothly moving the slider of the scroll box or manually in the box near the parameter (if required, the value bigger than maximum one for the slider can be set)
• color - the color can be chosen in the dialog window, activated after double clicking the color field

All the parameters can be set to default ones - click a Set to parent button near the parameter (if the parameter is different from the default one, its field will be highlighted with green).

The parameters available for this kind of materials are listed below.

Transform Parameters

Texture transformation parameters are modified in the Transform field of the Parameters tab.

GUI name	XML name	Type	Description
Attenuation	attenuation_transform	expression	V coordinate of the attenuation texture coordinates transformation. V coordinate of the attenuation texture.
Scale	base_scale	expression	Coordinate transformation of the density texture. Scale = (1, 1, 1) Scale = (2, 2, 1)
Offset	base_offset	expression	An offset of the density texture along X, Y and Z axes respectively. (For example, this option can be used to animate the cloud.)

Notice

Besides the native texture coordinates transformation, there are more options of setting texture coordinates. They are described in the Texture coordinates transformation article.

Shading Parameters

Density Parameters