Daily Updates (24th July 2013)

Lesson 3 - Custom Shader (Modifying Mantra Surface Shader)

v  creating modifier for mantra surface shader that helps to enhance

v  the capability to add maps, gradients and color map to any channel.

v  vop based digital assest

v  difference between exposing and promoting parameters

v  ramps in a shader

v  digital assest network

Creating the Shader 

Surface model is a VOP node that was previously introduce in Houdini 11.
It is really flexible and versatile as it has most the parameter you want in a shader, for example : Subsurface Scattering, reflections, refractions, fresnal, etc.

• Bias Amount

I want the bias amount from the color mix node to be access on the shop level on the vop material. For me to be able to do that, I would need to promote and expose parameters.

• Adding a file texture

I can also add an a file image for my textures by using color map and promote parameter for base and use color map.

• Ramps

Ramp parameter allows me to add more colors, and the bias amount would control how much ramp color or file image textures I want. This gives me more control.

We could nice outcomes with ramp parameter and color map and overlay many things together.

• Null

Adding a null before the ramp parameter always me to compile networks to the null on a digital assest and i am able to reuse.
I am also able to add or replace patterns into the null without affecting other nodes.
Creating Custom Shader Digital Assets
After creating all the parameters we want to able to adjust, it is time to make it into a digital assets so it can be reuse.

- Null (exposing parameter from the null node)

-make sure that "use input value if parameter not bound" selected

Issue

- If I use two of the custom shader I made, I get two each parameter but I do not get a second ramp because of the naming convention
Lesson 4 - Shader Development

Creating a 3d Shader

 U,V,W Coordinates

It is commonly used to convert a 2D image to a three dimensional object

It allows texture maps to wrap in irregular surfaces.

 To be able to create the 3d shader, we would have to add in a W coordinate.

• Duplicate the checkered shader and save it as an otl with another name

(Right click and "Allow Editing of Content") and it would turn blue.

• Right click on the node and click operator type manager. Here, I could duplicate the node and create the same node with another name, so I do not touch the original checkered node.

In order to create W coordinate on the new checkered 3d that has been created we would to add in more nodes inside of the pattern.

In the 13 minute of the lesson, Ari when through some of the nodes that were made checkered pattern. The nodes were isConnected and ifConnected.

isConnected - Test if the value is true or false
ifConnected - passes the value through

Creating New Variable to create the W coordinate

• Under the checkered3d node, right click and choose "Type Properties"
  Under the parameter tab, create 2 new float values

• Under the input/output tab create a new float value for W coord.

Now if I connect the surface position to the W coordinate, I get this 3d pattern on the box