Advanced Maya Texturing and Lighting- P7 pot

For example, in Figure 5.24 a checker texture is mapped to a surface shader material as a spherical projection.. This scene is included on the CD as proj_persp.ma.Placing Placement Boxes

appear That is, the upper edge of the texture is pinched into a single point, as is the

lower For example, in Figure 5.24 a checker texture is mapped to a surface shader

material as a spherical projection The top and bottom portion of the checker is

col-lapsed at the poles A similar problem occurs with a nurBs sphere; even though all

nurBs surfaces have four edges, two of the edges are collapsed into single points at

the sphere’s top and bottom pole

Figure 5.23 Planar projections mapped to various primitive surfaces This scene is included on the CD as proj_plane.ma

only for a Spherical projection type U Angle is functional only for Spherical and Cylindrical projections

Figure 5.24 (Left) A Spherical projection with default settings is applied to a sphere (Right)

The Spherical projection’s U Angle is set to 360 and its V Angle is set to 180 This scene is included

on the CD as proj_spherical.ma

Ball places the texture inside a projection sphere The projection pinches the texture

at only one pole A real-world equivalent is a blanket draped over a ball with the ket’s four corners twisted together at one spot The pole is indicated by the diamond-shaped uV origin symbol on the projection icon (see Figure 5.25)

blan-Figure 5.25 (Left) A Ball projection is applied to a sphere (Middle) The Ball projection icon (Right) The test bitmap This scene is

included on the CD as proj_ball.ma

Cylindrical places the texture inside a cylinder The left and right edges of the texture

will meet if the projection’s u Angle is set to 360 degrees The cylindrical type creates two pinched poles at the top and bottom of the projection (see Figure 5.26)

Cubic places a texture onto the six faces of a cube (see Figure 5.27).

Figure 5.27 A Cubic projection applied to a sphere This scene is included on the CD as proj_cubic.ma

Concentric randomly selects vertical slices from the texture and projects them in a

concentric pattern

TriPlanar projects the texture along three planes based on the surface normal of the

object that is affected

Perspective projects the texture from the view of a camera (see Figure 5.28) For this

to work, a camera must be selected from a drop-down list provided by the link To

camera attribute (found in the camera projection Attributes section of the

projec-tion utility’s Attribute editor tab) The projecprojec-tion icon will take the form of a camera

frustum but will not be aligned to the chosen camera in 3D space The frustum can

be “snapped” to the camera, however, by connecting the Translate, scale, and rotate

attributes of the camera’s transform node to the same attributes of the 3D placement

node connected to the projection utility node (For more information on custom

con-nections, see chapter 6.)

Figure 5.28 A Perspective projection applied to a series of spheres This scene is included on the CD as proj_persp.ma.

Placing Placement Boxes and Projection Icons

The translation, scale, and rotation of a 3D placement utility’s placement box or jection icon affect the application of the texture mapped to it For 3D textures, i sug-gest the following tips for placing the placement box:

pro-i

• f a surface is already assigned to the material to which the 3D placement utility belongs, click the Fit To group BBox button in the 3D Texture placement Attri-butes section of the 3D placement utility’s Attribute editor tab This snaps the placement box to the bounding box of the surface

i

• f you need to translate, scale, or rotate the placement box, select the Texture icon in the Hypershade window you can also click the interactive placement button found in the 3D placement utility’s Attribute editor tab The interactive placement button selects the placement box and displays an interac-tive translate, rotate, and scale handle

place3d-u

are not accurate representations of the way in which the texture will render

This remains true if the placement box is scaled to fit the assigned surface Trial and error renders provide the best fine-tuning method in this situation

For 2D textures mapped with the As projection option, the following tips are suggested for placing the 3D placement utility’s projection icon:

T

editor tab is identical to the Fit To BBox button found in the projection utility’s Attribute editor tab you can use either button to snap the projection icon to the assigned object or assigned group’s bounding box

i

• f you need to translate, scale, or rotate the projection icon, select the Texture icon in the Hypershade window you can also click the interactive placement button found in the projection or 3D placement utility’s Attribute editor tab The interactive placement button selects the projection icon and dis-plays an interactive translate, rotate, and scale handle

The projection icon created for projected 2D textures indicates the employed

uV orientation For example, a planar projection icon features a diamond-shaped

symbol at one corner (see Figure 5.29) This represents the 0, 0 origin in uV texture

space (For more information on uV texture space, see chapter 9.) using the origin

symbol as a reference, you can orient the icon and predict the resulting render For

example, if a planar projection icon is viewed from a front workspace view and the

origin symbol is at the bottom-left corner, V runs down to up and u runs left to right,

matching a texture’s icon in the Hypershade window

Figure 5.29

The UV origin symbol of a projection icon

spherical, cylindrical, Ball, Triplanar, and cubic projection icons also carry an origin symbol For Ball projections, the diamond shape represents the point where all

four corners of the texture converge Triplanar projections carry three origin symbols,

one at the corner of each plane each plane is identical to a planar projection cubic

projections carry six symbols, although three of them overlap at one corner

concen-tric projections carry no symbols since standard uV interpretation does not apply

For each and every example in this section, animation of the assigned surface can adversely affect the projection if either the surface or the projection icon is moved, the

surface picks up a different portion of the texture if the surface is larger than the

pro-jection icon or is not aligned to the icon, it receives a repeated portion of the texture

To avoid this problem, you can parent the 3D placement utility to the surface

How-ever, this will not prevent errors when a surface deforms Fortunately, the convert To

File Texture tool is available

Applying the Convert To File Texture Tool

The convert To File Texture tool allows you to convert projected 2D textures, as well

as 2D and 3D procedural textures, into permanent bitmaps To apply the tool, follow

these steps:

1. select a material that has a projected or procedural texture assigned to one or

more of its attributes shift+select the surface to which the material is assigned

2. choose edit > convert To File Texture (Maya software) > ❑ from the

Hyper-shade window menu The convert To File Texture options window opens (see Figure 5.30)

written out choose appropriate sizes and specify a File Format value Then click the convert And close button

The Convert To File Texture Options window

For each projected 2D texture, procedural 2D texture, and procedural 3D ture mapped to the material, a bitmap is written to the following location with the following name:

tex-project_directory/texture_name-surface_name.format

At the same time, the original material is duplicated with the original shading network structure in place of the projected and procedural textures, however, File textures are provided with the new bitmaps preloaded The new material is automati-cally assigned to the surface When compared side by side, the converted bitmap sur-face is virtually identical to the original (see Figure 5.31) once the converted bitmaps are applied to the surface through the duplicated material, you can delete the original material Thereafter, you can animate or deform the surface; the textures will not slide

This offers the advantage of locking in any custom UV settings In addition, any bitmap mapped to a single channel attribute, such as Transparency or Diffuse, is converted to grayscale The original bitmaps are not harmed

Lambert material or if the surface is connected to more than one shading group In general, the default Lambert material should not be used in the texturing process You can delete connections to unneeded shading groups in the Hypershade window

Surface with procedural textures Surface with converted bitmap textures

Figure 5.31 Procedurally mapped surface compared to surface with converted bitmaps This scene is included on the CD as

convert.ma

The convert To File Texture tool carries additional attributes for fine-tuning

Anti-Alias, if checked, anti-aliases the bitmap Background Mode controls the

back-ground color used in the conversion Fill Texture seams, when checked, extends the

color of any uV shell past the edge of the shell boundary; this prevents black lines

from forming at the boundaries when the surface is rendered Bake shading group

lighting, Bake shadows, and Bake Transparency, when checked, add their namesake

elements to the converted bitmap Double sided must be checked for Bake shadows to

function correctly uV range allows the custom selection of a non-0-to-1 range (it is

also possible to bake lighting information through the Transfer Maps window, which

is discussed in chapter 13.)

Chapter Tutorial: Creating Skin with Procedural Textures

in this tutorial, you will texture a character’s head using nothing more than 2D and

3D procedural textures (see Figure 5.32) Although custom bitmaps generally create

the highest level of realism, the proper use of procedural textures can save a

signifi-cant amount of time on any production

1. open head.ma from the chapter 5 scene folder on the cD This file contains a

stylized polygon head

area Assign the Blinn to the head open the Blinn’s Attribute editor tab change the color attribute to a flesh color of your choice change the Ambient color

to a dark red This will give the surface a subtle, skinlike glow in the shadows

The Ambient color slider should not be more than 1⁄8 of the slider length from the left side if the Ambient color is too strong, the surface will look washed out and flat

Figure 5.32 A skin material created with 2D and 3D procedural textures.

3. To properly judge the results, create several lights Follow either the 2- or 3-point lighting techniques discussed in chapter 1 render a series of tests until the lighting is satisfactory

button and choose a Fractal texture from the create render node window

Double-click the place2dTexture1 icon in the work area, which opens its bute editor tab set repeat uV to 15, 15 and check stagger This reduces and randomizes the scale of the fractal pattern so that it can emulate pores

Attri-5. open the Blinn’s Attribute editor tab Adjust the eccentricity and specular roll off attributes correct values depending on the lighting of the scene The goal

is to create a strong specular highlight without losing the detail provided by the Fractal texture Be careful not to raise the eccentricity value too high; this will spread out the highlight and make the skin look dull

its Attribute editor tab reduce the Amplitude and raise the Threshold slightly

This reduces the amount of contrast in the fractal pattern and makes its effect subtler Tint the color gain attribute a pale blue This inserts a color other than red into the material and helps make the skin color more varied

Map button choose a granite texture from the create render node window

in the work area, double-click the bump3d1 icon, which opens its Attribute editor tab change Bump Depth to 0.005 in a workspace view, select the 3D placement utility’s placement box and scale it down to 0.5, 0.5, 0.5 in x, y, Z

render a test The granite texture provides a subtle bumpiness/fuzziness to the parts of the skin that do not have specular highlights

Map button and choose a solid Fractal texture from the create render node window in the work area, double-click the solid Fractal icon (named solid-Fractal1), which opens its Attribute editor tab change the ratio value to 1 and the Frequency ratio value to 4 change color gain to a dark purple render a test frame The solid Fractal texture introduces variation within the basic skin color if the result is too bright or the color is not quite right, adjust the color gain and render additional tests

The skin material is complete! if you decide to apply this material to a character that moves or deforms, you can use the convert To File Texture tool to change the 3D

procedural textures into bitmaps if you get stuck with this tutorial, a finished version

is included as head_finished.ma in the chapter 5 scene folder on the cD

6

Creating custom shading networks is a powerful way to texture and render with Maya You can connect hundreds of material, texture, geometry, light, and camera attributes through the Hypershade window for unique results In addition, you can apply specialized color utilities that can customize the hue, saturation, value, gamma, and contrast of any input and output

Chapter Contents

A quick review of the Hypershade window Multiple approaches for creating connections Tips for keeping the Hypershade organized Practical applications of each color utility6

Mastering the Hypershade Window

the Hypershade window is the heir to the multilister domain although the ister window is a legacy tool from poweranimator, the Hypershade was created spe-cifically for maya everything that can be done in the multilister can be done in the Hypershade, but not vice versa you can access the Hypershade by choosing Window >

multil-rendering editors > Hypershade you can access the multilister by choosing Window >

rendering editors >multilister

Reviewing the Basics

the Hypershade window allows the connection of various maya nodes technically speaking, a node is a construct that holds specific information plus any actions asso-ciated with that information a node might be a curve, surface, material, texture, light, camera, joint, iK handle, and so on any box that appears in the Hypergraph

or Hypershade window is a node (For a differentiation between transform and shape nodes, see Chapter 7.) a node’s information is organized into specific attributes if an attribute can be animated, it is called a channel (and appears in the Channel Box) For example, the scale X of a sphere is a channel

you can connect attributes in an almost endless fashion a series of connected nodes is a node network if the network is designed for rendering, it’s called a shad-ing network any node connected to any other node is considered upstream or down-stream an upstream node is a node that outputs information a downstream node

is a node that receives or inputs information the node icons themselves will show if

an upstream or downstream connection exists if the bottom-left arrow is solid, the node is downstream of another node if the bottom-right arrow is solid, the node is upstream of another node if either arrow is hollow, a connection does not exist in the direction in which the hollow arrow points (see Figure 6.1)

Upstream node

Upstream connectiondoes not exist

Downstreamconnectionexists

Downstreamconnectionexists

edit > duplicate > Without network from the Hypershade menu to copy entire

shad-ing networks, choose edit > duplicate > shading network.

you can export shading networks Choosing File > export selected network

saves the selected network, by itself, in a file with the .mb or .ma extension you can

then bring networks back into the maya scene by choosing File > import from the

Hypershade menu

to assign materials, mmB-drag them on top of geometry in a workspace view

alternatively, you can follow these steps:

to selection from the marking menu

Creating Custom Connections

you can create custom connections through the Connection editor (choose Window >

general editors > Connection editor) or the Hypershade window’s work area

descriptions of various approaches follow

Using the Connection Editor

the Connection editor is divided into two sections By default, the left side contains

outputs (upstream) and the right side contains inputs (downstream) a single node can

be displayed on each side to load a selected material, texture, surface, or any other

maya node, click the reload left or reload right button

to make a connection, simply select an attribute on the left and an attribute on the right once a connection is made, the names of the attributes become italicized a

number of attributes are grouped into sets of three, as represented by the plus sign (see

Figure 6.2) this grouping is a type of vector (see Chapter 8 for a discussion on

vec-tors.) it occurs most commonly with the Color attribute, which is composed of red,

green, and Blue channels, but it also applies to color-driven attributes such as

trans-parency and incandescence you can reveal the individual channels of any given vector

attribute by clicking the plus sign

Vector attribute

Vector attribute with channels visible Single attribute

Figure 6.2 Vector attributes and a single attribute in the Connection Editor

other attributes, such as translate or normal Camera, represent a spatial tor with X, y, and Z coordinates any vector attribute can be connected to any other

vec-vector attribute However, a vec-vector attribute cannot be connected to a single attribute

Single channel of vector attribute to single attribute

Vector attribute to vector attribute

Figure 6.3 (Top) A vector attribute connected to second vector attribute (Bottom) The

single channel of a vector attribute connected to a single attribute

Color, the most common attribute, is predictably named Color on the input (downstream) side of a node However, it is named out Color on the output (upstream) side similarly, there is out glow Color, out alpha, and out transparency see the end of this section for a discussion of out alpha and out transparency

Employing Drag and Drop

dragging and dropping one node on top of another using the mmB automatically opens the Connect input of menu (see Figure 6.4) the default attribute (usually Color) of the output (upstream) node is automatically used for the connection the Connect input of menu makes no distinction between vector and single attributes if

a Connect input of menu selection is made that confuses the program, the tion editor automatically opens the attributes listed by the Connect input of menu

Connec-is incomplete (although they are the most common and often the most useful) to see the full list, choose other to open the Connection editor dragging and dropping one node on top of another using the mmB while pressing shift opens the Connection editor immediately

Figure 6.4

The Connect Input Of menu for

a Blinn material

for both nodes is used For instance, the default input attribute of a Blinn

mate-rial is Color the default input attribute of a bump2d node is Bump Value if the two

nodes involved in the connection are not a standard pair, maya will not be able to

make a decision For example, dragging one texture on top of another texture with

the mmB and Ctrl forces maya to open the Connection editor

you can also mmB-drag nodes from the Hypershade window to the attribute editor an outlined box appears around any valid attribute when the mouse arrow

hovers over it (see Figure 6.5) releasing the mouse button over an attribute

automati-cally creates a connection in this case, it’s best to double-click the downstream node

first to open the node’s attribute editor tab, and then mmB-drag the upstream node

without having actually selected it of course, clicking the standard checkered map

button on an attribute editor tab opens the Create render node window and creates

a connection once a material, texture, or utility is selected

+

Figure 6.5

A node MMB-dragged to the Attribute Editor

The outlined box around the attribute signifies a potentially valid connection

Duplicating a Line

left mouse button (lmB)-clicking and -dragging an existing connection line creates

a brand-new ghost line if the ghost line is dropped onto another node, the Connect

input of menu opens if you click the original line behind the arrowhead, the ghost

line starts at the input (downstream) node if you click the original line ahead of the

arrowhead, the ghost line starts at the output (upstream) node the attribute for the

node from which the ghost line extends will be the same as the original connection

line (see Figure 6.6)

the output (upstream) attribute is displayed in the white label box to the left of the

mouse arrow, while the input (downstream) attribute is displayed in the white label

box to the right of the mouse arrow For example, when examining the connection in