blender material nodes

7/30/2019 Blender Material Nodes

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Car paint, material by Matt Ebb(MPEG4, 500 KB / XviD AVI, 650KB/ .blend file )

Node setup

Ice, by Andy Goralczyk ( MPEG4,200KB / .blend file )

Node setup

Frosted glass, by Claas Kuhnen (.blend file ) Node setup

Blender's Material system was, until now, assuming a fixed set of

variables for shading and a limited set of 'channels' available for

mapping Textures on these variables.

The obvious advantage was that these settings were visible at a glance,

allowing quick setup of most of the basic Material features.

Currently most 3D suites have some kind of "shader editor", typically

represented as Nodes or Trees. Whilst constructing Materials out of its basic shader components allows a

high level offreedom, it can also turn out to be a very tedious job. Shader networks consisting of many

nodes can become confusing and hard to understand.

To combine the best of two worlds, whilst also allowing a Blender-compatible migration, a hybrid version

has now been implemented in Blender.

Read about general implementation notes for Nodes here.

Layering Materials

The original request was to look at ways to combine or layer multiple Materials, allowing the use of several

shading passes, one on top of the other, and also bypassing the limited number of texture channels. A

simple layer editor was constructed, which did not satisfy users. The next step was to implement this, this

time, using Nodes.

Examples


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Toon shader, by Claas K uhnen

Node setup

Press "Add New" (or use small menu button left of it) Press "Nodes" (or "Use Nodes")

Press red button "Add New" to link a new Material to

the Node

Getting StartedIf using Blender Nodes for the first time, check the general editing information on the Nodes UI page.

Enabling Nodes editing involves these two steps first:

Create a workspace in your screen with a Node Editor window.

Open the buttons window with the a view on the Material options

In this example we assume the active Object doesn't have a Material yet. The pictures below then show the

following steps:

1. Object with no Material

2. Press "Add New" (or use small menu button left of it)

3. Press "Nodes" (or "Use Nodes")

4. Link a new Material to the Node


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Two nodes, mixed Cleaned up

We have now created the following situation:

A base Material (1), which we use to link to Objects

Added a NodeTree to this base Material with two nodes and a

link

Linked the Material Node to a new Material (2)

This means a Blender Material can be used in three ways now.

1) As usual, a fixed block of settings you can link to Objects

2) As a base for a NodeTree; in this case browse menus will indicate that Material with a "N".

3) As a Node inside a NodeTree.

Some of the Material settings are not part of the shading system,

but define how the geometry is being used in the rendering

pipeline. These settings cannot be used per Node or be layered.

You can find these settings, and the buttons to browse/link

Materials, in the new "Links and Pipeline" Panel. Here you define

settings like "Halo" or whether the faces with this material are

included for ray-tracing or shadow buffers.

The situation we've created now works in the Buttons windowexactly as if a single Material were used, with the exception that

the base-Material stores the 'render pipe line' settings, and the node-material stores all shading

information.

You may also notice that the Material Node input values are synchronized with the Material itself when

changed. Only when the input sockets are used, are these values overridden.

Layering Materials

The steps to create two materials which are mixed is simple:

Select the Material Node

Shift D to duplicate it

Use the menu button in the new Node to assign it a new Material (menu item "Add new").

Selecting a Material Node also updates the settings in the Material buttons, this way you can give both

Nodes a different appearance.

Press Shift A and choose "Color Mix" to add a Mix Node.

Create the proper links to make it actually work (1st picture)

When you don't need to further edit this situation, you can clean up the Node view by using the buttons in

the Node header to hide the unused inputs and buttons, and to minimize the Mix Node. (2nd picture)

Node TypesOutputThe Output Node can be used anywhere in a network, and offers preview renders of the Material at the

linked location. The first added Output is the Output used for rendering, with a red sphere icon on the

Node to indicate this.

Material


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The Material Node will do a full shading (for all indicated lamps) similarly to using a regular Material. Note

that all calculations (Shadows, Ambient Occlusion, etc., etc) occur for each Material Node.

Currently a Material only allows four inputs, this is a candidate to be expanded.

TextureThe Texture Node requires a vector (texture coordinate) as input to work. Typically you'll use the Geomotry

Node as Input.

GeometryAll Material Nodes in a tree will always use the same texture coordinates. These can be accessed with this

Node, for example as Texture input.

GroupWhen you group Nodes (CTRL+G), this Group becomes a new Node Tree in the Blender Library, which then

can be linked by a "Group Node" to be re-used anywhere you want. More about Groups here.

MixThe Mix Node acts as a "pass-thru" for the first (top) Color input, and uses the "Fac" value to determine the

level that the second input effects the result, under the given operation. With "Fac" set to zero, no operation

occurs.

RGB CurvesThis Node shows a new UI widget, the "Curves". You can use it to adjust overall brightness or the individual

RGB channels. More about Curves widget.

NormalUse the Normal Node to define a fixed normal, or to perform a dot product with this normal. When used for

shading, this normal is in "camera space".

MappingThe Mapping Node can be used to clamp/translate/rotate/scale Vectors or Colors.

Vector CurvesAlthough this Node operates in a similar manner to the RGB Curves Node, it is initialized properly for 1:1

mapping and clamping values between -1 and 1. More about Curves widget.

Color RampThis Node converts a value to a RGB color and Alpha using a Ramp. The ramp editing works as per regular

ramps in the Blender UI (CTRL+click to add new key positions).

RGB to BWA simple color to value convertor

ValueThis Node generates a Value

RGBThis Node generates a Color

Next stepsThe current system will still need some evaluation...

Ray-traced mirror or transparency inside of Material Nodes is not well handled yet. This because the use

of node trees makes it impossible to retrieve a singular Material property (like, does this point on a face


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reflect or not?).

What does work is having a regular material that mirrors another material with a nodetree. We have to work

still on this topic.

Although it works quite well to have a full Material available as a Node, it can result in very slow rendering

when multiple Nodes require shadow or raytracing results. This can be solved by recoding the core internal

rendering loop to be made more "pass aware". Meaning, before Blender starts executing the Nodes, the

required AO render, shadow or raytrace results can be precalculated.

Since Nodes allow a high level of freedom to mix whatever you like, it is not easily possible to extract the

individual Passes, such as, only diffuse, or only specular, etc. This requires further research.

More Node types can be added, especially for lower level shading (like a Diffuse Node, or a Shadow

Node). This will require a good balanced design in advance though, something for which I'd welcome

contributions.

Preliminary tests were done to create Python Nodes, actually fully customizable and programmable

shaders. Requires further work still.

blender material nodes

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