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VRML Script Tutorial
Full list
VRML Interactive Tutorial
Introduction
VRML File Structure
Drawing: Shape node
Geometry Nodes:
Appearance
Let there be Light
Materials with Colored Lights
Hierarchical Node Structures
Inlining Files
Defining and Instancing Nodes
Defining Levels of Detail
Events in VRML
Interpolators
Let the Music Play
Bindable Nodes
Adding Realism to the world
Information about your world
Definition for Auxiliary Nodes
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IndexedFaceSet Node
The IndexedFaceSet node specifies a set of planar faces in the local coordinate
system.
The coord field specifies a Coordinate
node. In this node a set of 3D coordinates are given.
The coordIndex field specifies a list of coordinate indexes defining
the faces to be drawn. To separate the indexes from a face the marker -1
is used, i.e. an index of -1 indicates that the current face has ended
and the next one begins.
Because the faces are always defined by closed polylines, you don't need
to define the first point twice. Consider the following values for coord:
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coord Coordinate{
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point [ 0 0 0, 1 0 0, 1 1 0, 0 1 0]
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}
Four points are defined, when you join the points you can make a square
face. The coordIndex used for a square face could be:
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coordIndex [ 0 1 2 3]
What the above coorIndex meaning is: Join the first point in the
coordinate list to the second point, then join the second to the third,
the third to the fourth, and finally the fourth to the first to close the
region which defines the shape.
The color field defines a Color
node. This node defines a list of colors to apply to the faces. The color
is optional, the default values being applied if the field is not specified.
If a Material node is specified
the default color is the emissive color from this node. Note that both
the default emissive color and background are black, so if no color is
specified and the default background is used you won't be able to see the
faces.
The colorIndex serves the same purpose as the coordIndex
but regarding colors. IF colorIndex is not specified then coordIndex
is used instead.
The colorPerVertex is a boolean field which defines how the colors
are applied. The meaning is similar to the IndexedLineSet
case.
texCoord specifies a TextureCoordinate
node.
texCoordIndex has a similar meaning to coordIndex but applied to Textures.
There are 3 normal fields which have the same meaning than the color fields
but applied to normals. The normal
field defines a Normal node.
The ccw field specifies if the points which define a face are present
counterclockwise, TRUE, or clockwise or unknown order, FALSE. A face has
two sides and sometimes it is important to know which is the front side,
and which is the back side. So let's assume you're defining a single face
perpendicular to the Z axis and ccw is TRUE. If the face is defined
counterclockwise then the front side is the side facing you. Otherwise
the back side is facing you. If ccw is FALSE then the opposite occurs.
The solid field determines if the browser should draw both sides
of a face or just the front side. VRML assumes by default, solid is
TRUE that the faces in an IndexedFaceSet form a solid shape. In this case
there is no need to draw the back sides of each face. If solid is
FALSE then the browser will draw both sides of each face.
The convex field specifies if the faces being defined in coordIndex
are convex or not. VRML can only draw convex faces. When presented
with concave faces, the browser splits the face into smaller convex faces.
This is a time consuming task. If you are sure that all your faces are
convex then setting this field to TRUE tells the browser not to worry splitting
the faces, and therefore saving time. The creaseAngle specifies
an angle threshold. If two adjacent faces make an angle bigger than the
creaseAngle then you'll see clearly where the two faces meet, the edge
linking the two faces is sharp. Otherwise the edge linking the two faces
will be smooth.
Syntax:
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IndexedFaceSet { |
coord NULL
coordIndex [ ]
color NULL
colorIndex [ ]
colorPerVertex TRUE
normal NULL
normalIndex [ ]
normalPerVertex TRUE
texCoord NULL
texCoordIndex [ ]
ccw TRUE
convex TRUE
solid TRUE
creaseAngle 0.0
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} |
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