From LuxRender Wiki
This page describes functionality that can be accessed through Blender's material and texture panels when LuxBlend25 is activated. For more general information about using LuxBlend25, please visit the LuxBlend25 Manual page.
LuxRender's materials are mostly defined in two tabs: the material tab and the textures tab. Those two tabs are linked in a way: the texture tab only shows the textures that belong to the active material, while a material can only use those textures that have been assigned to it in the texture tab.
Full descriptions of all available materials can be found on the materials page, this page will just describe the basic principles of creating materials in LuxBlend25.
The top section of the material panel contains a list of all the materials that are assigned to the current object or mesh. Existing materials can be assigned or removed and new materials can be created. Here is where you set the material type (matte, glossy, metal, carpaint, etc) and configure volumes, bump, and normal maps for this material.
If you have PyLux installed, you will also be able to see a preview of your material in the materials editor. This preview will auto-refresh when you open the materials editor. Currently, sphere, cube and monkey preview types are supported. You can force an update of the preview by clicking one of these three buttons. You can also use the controls below the image to adjust the size of the preview object and the position of the camera
These controls allow you to interface with the LuxRender Materials Database. You can browse the available materials and download them straight to the current material slot. If you are logged in to the database, you can also upload materials.
These are a set of utilities for managing your materials. You can save or load a material file, or convert the existing Blender material to LuxRender settings. Please note that the conversion functionality is rudimentary, in general it is best to start with LuxRender materials directly instead of converting them.
Here you can configure if the current material should emit light. Once you check the “use emission” box, you will be offered the standard emitter settings, such as color, power, gain, and luminous efficacy. Light color can be defined as a single color or as a texture. If you would like to use a blackbody spectrum, create a new texture with the “blackbody” type and assign it to the lamp color channel.
This panel provides a simple way to make alpha-mapped or transparent materials. Click the "transparent" checkbox to enable it. If your diffuse/reflection color texture is an RGBA image, you can use its alpha channel by setting the Alpha Source to "diffuse/reflection alpha".You can also select "mean" or "intensity" to take alpha from the general color of the texture.
If you would like to use a seperate alpha map from the texture being used on diffuse/reflection channel, or your material has no such channel (namely glass2) you can select "texture" and specify some other texture attatched to the material. Finally, if you don't want a texture at all, you can choose constant and simply define an opacity amount.
This panel provides a quick and simple way to use LuxRender's glossycoating material to add a glaze to the current material. Click the checkbox to enable it and configure the glossy coating options.
These are the individual channels and options for the selected material. The “T” boxes allow you to use a texture for that channel. If you click it, you will get a box where you can select one of the textures currently assigned to that material. There will also be an "M" box you can check to make LuxBlend25 multiply the texture by the specified color/value to get the final output. Otherwise, the original color/value is ignored. You can assign a texture to your material just as you would for Blender Internal, by going to the textures panel and adding it to a slot.
the mix material
If you are creating a mix material, you must choose its components from existing material indexes attached to that object. So any object that has a mix material will need at least 3 material slots: the mix material, component 1, and component 2. The 2 components need not actually be assigned to any faces on the object, they merely must be assigned to the object's data block.
Bump map information for the mix material is taken from both components, the bump map setting on the mix material itself is ignored. This allows you to mix bump map types for your different materials. If you want your bump map applied uniformly to the entire material, you should configure it identically for both components.
On the other hand, emission and interior/exterior volume settings will be taken from the settings on the mix material itself. This is because these settings are actually mesh properties, and the mix material is being used to define which faces will receive these properties.
The textures editor is much the same as it is for Blender Internal. You edit your textures there, and the parameters are largely specific to the texture type you are working on. You can assign textures to the currently selected material by assigning them to a slot. Note that the order of textures and the checkbox next to the texture slot don’t do anything when you have LuxRender set as your render engine. This is simply a bucket of textures you can assign to channels in the materials editor.
The texture type menu includes an entry for "use blender texture" that will use the currently selected Blender texture type. This takes over from the selection of “Blender Clouds” or “Blender Blend”, etc in the old LuxBlend. LuxRender will also translate Blender's image texture to it's own "imagemap" texture automatically. You can configure the image sampling settings as well. Note that LuxRender does not support all of Blender’s textures, such as voxel data. Selecting a texture type from a category other than "Blender textures" will cause the Blender texture type to be ignored, allowing you to access LuxRender specific textures such as "blackbody" and "band".
Some textures in LuxRender are "float" textures, meaning they are assigned to numeric fields, others are "color" meaning they are assigned to color fields (aka color swatches). Some textures can be set as either type. It is important to make sure you are using the right type of texture. The old LuxBlend protected the user from this distinction, by automatically using a mix texture when a float texture was assigned to a color field, by auto-setting the switchable to textures to the proper type, and not exposing the color-only textures for numeric fields. LuxBlend25 doesn't do any of this right now, you must manage it yourself. LuxRender will produce an error on startup if you have an incorrect assignment. If you would like to apply a float-only texture (such as blender clouds or wrinkled) to a color field, create a mix texture and use the float texture on the mix amount channel. You can set the color using the two color swatches on the mix texture.
NOTE: Blender's image texture will automatically set itself to the correct variant.