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-- File: Vrml_ShapeHints.cdl
-- Created: Tue Feb 11 11:33:49 1997
-- Author: Alexander BRIVIN and Dmitry TARASOV
-- <brivin@minox.nizhny.matra-dtv.fr>
---Copyright: Matra Datavision 1997
class ShapeHints from Vrml
---Purpose: defines a ShapeHints node of VRML specifying properties of geometry and its appearance.
-- The ShapeHints node indicates that IndexedFaceSets are solid, contain ordered vertices, or
-- contain convex faces.
-- These hints allow VRML implementations to optimize certain rendering features.
-- Optimizations that may be performed include enabling back-face culling and disabling
-- two-sided lighting. For example, if an object is solid and has ordered vertices, an
-- implementation may turn on backface culling and turn off two-sided lighting. To ensure
-- that an IndexedFaceSet can be viewed from either direction, set shapeType to be
-- UNKNOWN_SHAPE_TYPE.
-- If you know that your shapes are closed and will alwsys be viewed from the outside, set
-- vertexOrdering to be either CLOCKWISE or COUNTERCLOCKWISE (depending on
-- how you built your object), and set shapeType to be SOLID. Placing this near the top of
-- your VRML file will allow the scene to be rendered much faster.
-- The ShapeHints node also affects how default normals are generated. When an
-- IndexedFaceSet has to generate default normals, it uses the creaseAngle field to determine
-- which edges should be smoothly shaded and which ones should have a sharp crease. The
-- crease angle is the angle between surface normals on adjacent polygons. For example, a
-- crease angle of .5 radians (the default value) means that an edge between two adjacent
-- polygonal faces will be smooth shaded if the normals to the two faces form an angle that is
-- less than .5 radians (about 30 degrees). Otherwise, it will be faceted.
uses
VertexOrdering from Vrml,
ShapeType from Vrml,
FaceType from Vrml
is
Create ( aVertexOrdering : VertexOrdering from Vrml = Vrml_UNKNOWN_ORDERING;
aShapeType : ShapeType from Vrml = Vrml_UNKNOWN_SHAPE_TYPE;
aFaceType : FaceType from Vrml = Vrml_CONVEX;
aAngle : Real from Standard = 0.5 )
returns ShapeHints from Vrml;
SetVertexOrdering ( me : in out;
aVertexOrdering : VertexOrdering from Vrml );
VertexOrdering ( me ) returns VertexOrdering from Vrml;
SetShapeType ( me : in out; aShapeType : ShapeType from Vrml );
ShapeType ( me ) returns ShapeType from Vrml;
SetFaceType ( me : in out; aFaceType : FaceType from Vrml );
FaceType ( me ) returns FaceType from Vrml;
SetAngle ( me : in out; aAngle : Real from Standard );
Angle ( me ) returns Real from Standard;
Print ( me; anOStream: in out OStream from Standard) returns OStream from Standard;
---C++: return &
fields
myVertexOrdering : VertexOrdering from Vrml; -- Ordering of face vertices
myShapeType : ShapeType from Vrml; -- Info about shape geometry
myFaceType : FaceType from Vrml; -- Info about face geometry
myAngle : Real from Standard; -- Smallest angle for sharp edge
end ShapeHints;
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