Slim's Core Functions: Manifolds, Environment Lights

All functions operate on a domain. Some functions operate implicitly on a domain but most require its explicit specification. For our purposes, this means that functions require a description of the surface that they're operating on and this requirement comes is the form of a manifold parameter. A manifold function either generates or transforms function domains. Manifold functions encompass notions of 3D Surface Points, Reference Geometry, Projection, Tiling, Surface Parameterization and Warping. Manifolds are a generalization of point functions and carry with them derivative information useful in antialiasing calculations. A function network can operate on any number of manifolds but usually you'll choose a single manifold to drive all the calculations for a network.

MayaProj

Description:

FOR PLANAR PROJECTION:
Find the place3dTexture and place2dTexture nodes in the Maya hypershade graph for your projection. Create a RenderMan coordinate system and parent it under the place3d; enter its shape name under Place3d Coords. Make sure Perspective Coords is blank.

FOR PERSPECTIVE PROJECTION:
Look at "Camera Projection Attributes" of your Maya projection. Set "Fit Type" to "Match Camera Film Gate". Set "Fit Fill" to "Horizontal". Create a RenderMan coordinate system and parent it under the camera you chose in "Link to Camera"; enter the coordinate system's shape name under Perspective Coords.

FOR EITHER:
If you're using the place2d node, enter the expressions [st0 place2dTexture1] and [st1 place2dTexture1] under Place2d ST0 and Place2d ST1 respectively.(Replace place2dTexture1 with the name of your place2d node.)

OTHER PROJECTION TYPES: Are not supported by this function.

MayaUV

Description: A means to access Maya's version of the surface parameterization. Typically you'll want to connect the STMatrix parameters to a place2dtextures node. You can do this by changing these parameter's type to expression, then entering an expression of the form
[st0 place2dtextures]
into the STMatrix0 parameter. And similarly for STMatrix1, replacing st0 with st1. Note that place2dtexures should be the name of the place2dtextures node in your Maya scene.

Projection

Description: Converts a 3D surface point to a 2D texture coordinate through the magic of projection.

Projection
Select type of projection.

Planar for Textures
If you plan to use this projection for images and are using a planar projection, this control flips the sense of x and y and offsets the projection so that the center of the image is mapped to the origin.

angle
Rotate the projection in degrees.

S Repeats
Define repeats in S.

T Repeats
Define repeats in T.

S Offset
Shift the projection in S.

T Offset
Shift the projection in T.

manifold
Generally you'll want to attach a Surface Point manifold here, and in its "Space" parameter be sure to enter the shape name of the coordinate system being used for projection.

Scale

Description: Returns a non-uniformly scaled version of the
input manifold.

Frequency
Controls the scale of the manifold. Note that increasing the frequency of the manifold will result in decreasing the scale of a feature.

input

SurfPtLight

Description: Returns the 3D point on the surface of your light.

CoordinateSystem

UsePref
Causes the reference geometry to be employed during manifold calculations. This should only be enabled if your surface has the reference geometry attached.

SurfacePoint

Description: Returns the 3D point on the surface of your object.

Space
The name of a coordinate system for the manifold.

Frequency
Controls the scale of the manifold. Note
that increasing the frequency of the manifold will result in decreasing the scale of a feature.

IgnorePref
If you have attached __Pref geometry and,
for debugging purposes, want to ignore it, click
here. Note that it's much more efficient to simply
remove the reference geometry if it's not needed.

Warp

Warp Function
Returns points additively warped by vector-value Unless you choose to map the Surface Point parameter, the default behavior is to use ST coordinates.

Kw
A multiplier for the warper.

Manifold

World Point

Description: Returns the 3D World space.

Frequency
Controls the scale of the manifold. Note that increasing the frequency of the manifold will result in decreasing the scale of a feature.

Offset
Use this parameter to offset the worldspace function. When connected to time or animated with an expression containing \$f, this parameter controls motion of all upstream functions.

Direction
Establishes the direction of the motion controlled by the Offset parameter.

VECTORS

A vector function calculates a 3D vector at every point. Vector functions are used to perturb, or warp, fields of points.

Brownian

Base Frequency

octaves
max # of octaves to calculate.

lacunarity
frequency spacing between successive octaves

gain
scaling factor between successive octaves

Fourth Dimension
You can get 4D brownian noise by connecting this parameter to any float function. Often you'll want to connect some function of time here.

manifold

Fractal

Description: Vector Fractal function.

Layers
The number of noise layers used.

Frequency
Sets the lowest (starting) frequency of the
noise layers.

Lacunarity
The scaler used to determine the
frequency of each sucessive layer of noise. Smaller numbers will cause the layers to be more closely spaced in frequency. Larger values will space them further apart.

Dimension
The frequency exponent. This value is used to scale the magnitude of each sucessive layer of noise using the formula 1/f^(3-2*Dimension); where f is the frequency of the noise being used for a given layer. It's called Dimension since this value relates to the fractal dimension. Bigger values are rougher, smaller values are smoother.

Flow Magnitude
Determines the degree to which the original space is warped by the vector fractal field by each sucessive layer.

Variation
This value controls which particular variation of the appearance you get - without altering the qualities of the appearance determined by the other controls. So, for example, you can use this to animate the appearance by connecting this to Time, or create several unique instances of the appearance by setting this to different values.

Manifold

ENVIRONMENTS

Environment Lights

Environment lights are special lightsource shaders that provide environmental reflections in your scene. These environment lights produce "fake" reflections, which are surprisingly convincing and much cheaper to render. Environment lights can create convincing reflections for a fraction of the time required for physically based solutions. The key idea here is that we can utilize a special lightsource to accomplish this. Environment lights provide reflection only light. This means that light that comes from environment lightsources only affects shiny objects, and then, only in the direction of the reflection.

You can insert any number of environment lights into a scene and optionally use the light link editor to ensure they affect only a subset of your objects. Typically, though, a single environment light is sufficient.

Blobby	A procedural environment
EnvMap	Add an image map as the environment.

Blobby

Foreground
Color of the foreground

Background
Color of the background

Complexity
Control the scale of the blobbiness

Variation
This will is useful to tie to a function such as time to vary the appearance during an animation

Space
Define your favorite shader space here

EnvMap

File
The name of the Environment Map to use.

Space
Choose the coordinate system in which to access your environment map. If you've computed an environment map from the associated object you should use \"shader\" otherwise \"world\" may be a safe choice.

Right Handed
Used to correct the reflection direction to account for a right handed coordinate system. Maya, for example, operates in Right Handed coords.

Up Correction
Used to correct for discrepancy between the up direction of the map and your coordinate system. Y->Z is the most common choice.

MayaProj	Generally ape Maya 2D projections.
MayaUV	Connect STMatrix parameters to a Maya node.
Projection	This is staple projection manifold.
Scale	Rescale other manifolds with this.
Shear	Applies a shear effect.
ST	Returns a 2D surface point.
SurfPtLight	For use with lights.
Surface Point	Returns a surface point.
Tile	Use to tile other functions.
Warp	Apply warp to other functions.
WorldPoint	Returns a point in world space.

Brownian	Create a Brownian noise.
Fractal	A fractal noise.
Noise	A basic fractal.

SLIM's CORE FUNCTIONS

The Core Set of Functions

MANIFOLDS