## UE4 – Procedural 3D noise bump setups

Software:
Unreal Engine 4.25

Yet another case where I develop my own costly solution only to find out afterwards that there’s actually a much more efficient built-in solution.. ðŸ˜€

In this case the subject is deriving a bump normal from a procedural or non-uv projected height map/texture (like noise, or tri-planar mapping for example).

The built-in way:
Using the pre-made material functions, PreparePerturbNormalHQ and PerturbNormalHQ, the first of which uses the low level Direct3D functions DDX and DDY to derive the two extra surface adjacent values needed to derive a bump normal, and the last uses the 3 values to generate a world-space bump normal:

1. Noise coordinates are obtained by multiplying the surface shading point local position by a value to set the pattern density.
2. The Noise output value is multiplied by a factor to set the resulting bump intensity.
3. The PreparePerturbNormalHQ function is used to derive the 2 extra values needed to derive a bump normal.
4. The PerturbNormalHQ function is used to derive the World-Space bump normal.
5. Note:
Using this method, the material’s normal input must be set to world-space by unchecking Tangent Space Normal in the material properties.

The method I’m using:
This method is significantly more expensive in the number of shader instructions, but in my opinion, generates a better quality bump.
Sampling 3 Noise nodes at 3 adjacent locations in tangent-space to derive the 3 input values necessary for the NormalFromFunction material function:

1. Noise coordinates are obtained by multiplying the surface shading point local position by a value to set the pattern density.
2. Crossing the vertex normal with the vertex tangent vectors to derive the bitangent (sometimes called “binormal”).
3. Multiplying the vertex-tangent and bitangent vectors by a bump-offset* factor to create the increment steps to the additional sampled Noise values.
* This factor should be parameter for easy tuning, since it determines the distance between the height samples in tangent space.
4. The increment vectors are added to the local-position to get the final height samples positions.
5. The NormalFromFunction material function is used to derive a tangent-space normal from the 3 supplied height samples.

Note:
From my experience, even though the UV1, UV2 and UV3 inputs of the NormalFromFunction are annotated as V3, the function will only work is the inputs are a scalar value and not a vector/color.

## Blender – Basic time-dependent animation driver examples

Software:
Blender 2.82

To setup a time-dependent Driver in Blender, simply use the built-in frame variable.
In this example the expression:

`sin(frame)`

Set as a Z axis location driver for the cube causes it to oscillate up and down:

Changing the expression to:

`sin( frame * 0.1 ) * 2`

Causes the motion to be twice as high and 10X slower:

In this example, the expression:

`( pow( -1 ,  floor( frame / 30 ) )  *  0.5 ) + 0.5`

Set to the cube’s Emission shader’s Strength attribute causes it to alternate between values of 0 and 1 every second (30 frames in this case):

## UE4 – Blueprints – Set Parent Class

Software:
Unreal Engine 4.24

When It comes to OOP inheritance, the best practice is to take a moment to think about code structure and decide which classes should be be extensions of a common super-class. But in a wild hackathon or game-jam, we may be blueprinting too hastily for that, and we may find out different blueprint classes actually have to be child classes of a common parent class after they already exist and have existing blueprints in them.
In this case will have to Set their parent class as a different class than the class we chose when we initially created them, and also create calls to the parent class event functions if needed.

Setting a BP’s parent class:

Click Class Settings, and under Class Options, in the Parent Class drop-down select the wanted parent class (superclass).

Calling the Parent Class’s event functions:

Note:
When creating a BP class that is defined as child class in its creation this is done automatically

1. Right-Click the current class’s Event icon, and select Add call to parent function:
2. Connect the execution flow graph, and other inputs if necessary:

## UE4 – Material Functions explanation and Example

Software:
Unreal Engine 4.24

Material Functions encapsulate shading flow graphs (material blueprints) into reusable shading nodes that have their own inputs and outputs.
This allows development of custom shading nodes, and saving the time it takes to recreate the same flow graphs multiple times or even copy and paste material flow graphs.
Common shading processes and operations that have to be performed in many different materials, and even multiple times in a single material can be defined as a Material Function for quick and easy re-usability.
Material functions can also be used to encapsulate a full material blueprint with a Material Attributes output. this provides a convenient workflow for blending different materials together.

In this post I’ll detail the steps needed to create and use a Material Function.
The Material Function example we’ll create, called “ColorAngleBlend” performs a commonly needed shading operation of blending 2 colors or textures according to the surface viewing angle (facing ratio).

The ColorAngleBlend Material Function will have the following inputs:

1. color a:
The color or texture appearing when viewing the surface at perpendicular angle.
2. color b:
The color or texture appearing when viewing the surface at grazing view angle.
3. curve exponent:
The steepness of the blend curve between the colors, 1 being a linear blend and higher values displaying color a at more angles “pushing” color b to be seen only at grazing angle.
4. base color blend:
The percent of color b seen at perpendicular view angle.
5. normal:
bump normals input.

The final “ColorAngleBlend” Material Function Blueprint:
* The internals of the “ColorAngleBlend” Material Function

An example of the “ColorAngleBlend” Material Function node used to create a reach view-angle dependent color blend for a steampunk metal material:

An example of the “ColorAngleBlend” Material Function nodeÂ used to create a reach color for a car-paint material:

An example of the “ColorAngleBlend” Material FunctionÂ nodeÂ used to create a washed-out effect for a cloth material:
Steps for creating the “ColorAngleBlend” Material Function:

1. In the content browser, create a Material Function Object and name it “ColorAngleBlend”:

2. Double click the ColorAngleBlend Material Function to open it for editing:
3. Click the background of the work space to deselect the Output Result Node,
So that the Details panel on the left will display the Material Functions‘s properties.
Type a description into the Description field, check the Expose to Library option so that the new Material Function will be available to all materials in the Palate and node search, and define in which node categories it should appear:
4. Select the Output Result node and in the Details panel on the left set its output name to “color”:
5. Add a Linear Interpolate (Lerp) node, a Fresnel node and a Transform Vector (Tangent space to World space) node to the Blueprint and connect the nodes like this:
* The Lerp node will blend the 2 color inputs with the Fresnel providing view angle data as the alpha for the Lerp.
The Transform VectorÂ  node is needed to convert normal (bump) input to world space for the Fresnel node.
6. Adding function inputs:
Create 2 Function Input nodes, in their Details panel, name them “color a” and “color b”, leave their Input Type as default Vector3D, check the option Use Preview Value as Default, number their Sort Priority parameters 0 and 1 to make them appear as the first inputs of the ColorAngleBlendÂ node as it will appear when used in a material, and connect them to the Lerp node’s A and B inputs:
7. Adding function inputs:
Create 2 new Function Input nodes, name them “curve exponent” and “base color blend”, this time set their Input Type to Scalar, check the option Use Preview Value as Default, set their Sort Priority parameters to 2 and 3 and connect their outputs to the Fresnel node’s ExpoentIn and BaseReflectFractionIn inputs:
8. Adding function inputs:
Create the final Function Input node, name it “normal“, set its Input Type to Vector3D, check its Preview Value as Default option, set its Sort Priority to 4, and connect its output to the Fresnel node’s Normal input:
9. Adding default inputs:
Finally, add constant nodes to serve as default input values for the Material Function.
A pure white Constant3VectorÂ (color) constant as the default value for “color a” input,
A pure black Constant3VectorÂ (color) constant as the default value for “color a” input,
A Constant with value 1.0 as the default value for “curve exponent” input,
A Constant with value 0.0 as the default value for”base color blend” input,
A pure blue Constant3VectorÂ (color) constant as the default value for “normal” input.
> Tip for quick creation of constant value nodes
10. Save the new Material Function.

To use the new ColorAngleBlend Material Function create a new material, in the node search start typing color… to locate the ColorAngleBlend node and create it, and connect it to the desired material input.

> Material Functions can also be used by dragging them from the Content Browser into the Material Blueprint.

## Python for 3ds max – list scene objects

Software:
3ds max 2019

Iterating through a list of all of an object’s hierarchy or all of the objects in the scene is a very common requirement for scripted tools and utilities in 3D animation software.
Coming from a MaxScript background, I was used to just have to write the word ‘objects‘ to reference a list of all of the objects in the scene.

Unless I’m missing something obvious,
There isn’t a shortcut like this available in the 3ds max Python API.

In order to list all the objects in the scene you need to use a recursive function that will return a list of all of a node’s children, and children’s children, etc.

In the following example, the function ‘list_children()’ will return a list all of the objects in the supplied node’s hierarchy, and when given the scene’s root node via MaxPlus.Core.GetRootNode() it will return a list of all the objects in the scene.
Wrapping ‘list_children()’ within the ‘scene_objects()’ function, provides a convenient way get a list of all the objects in the scene just by calling ‘scene_objects()’.

```def scene_objects():
def list_children(node):
list = []
for c in node.Children:
list.append(c)
list = list + list_children(c)
return list
return list_children(MaxPlus.Core.GetRootNode())

for o in scene_objects():
print o.Name```

* note that when copying and pasting a script from this example, the indentation may not be pasted correctly.