shapes properties binding 2001.08.14 chung ji hye

Shapes Properties Binding

2001.08.14Chung Ji Hye

Graphics Laboratory Korea University ch

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Content

Use a variety of shapes in the sceneIndexed shapes specify their own orderDifferent effects for color values, shininess and transparencyRender a scene using different drawing stylesCreate a scene with fog Use the shape hintsMaterial and normal binding


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Shapes

All shape nodes are derived from the abstract base class SoShape

Simple shape Complex shapes CubeCube Face set Cone Line set Sphere Tirangle strip set Cylinder Quad mesh


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Complex Shapes[FaceSet]

SoFaceSet is a shape node Represents a polygonal object Current coordinates, normals, materials, textures Uses the values within each node in the order they are given

SoIndexedFaceSet Represents a polygonal object formed by constructing faces Uses those values in any order Contains four field


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Complex Shapes[FaceSet]

Four Fields coordIndex

Contains indices into the coordinates list SO_END_FACE_INDEX(-1)

materialIndex Contains indices into the current material for the materials of the f

ace set Use only when some type of indexed material binding is specified i

n the SoMaterialBinding node NormalIndex

Contains indices into the current normals SoNormalBinding node

TextureCoordIndex Contains indices of the texture coordinates


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Complex Shapes

Triangle Strip Set SoTriangleStripSet

constructs triangle strips out of the vertices One of the fastest ways to draw polygonal object Starting by startIndex field (in order)

Static long numvertices[2] ={32, 8};

SoTriangleStripSet *myStrips = new SoTriangleStripSet; myStrips->numbertices.setValues(0,2, numVertices);

//32 triangle stripset, 8 triangle stripset //face 0 determined the vertex ordering


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Triangle Strip Set

Triangle Strip Set Example


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Complex Shapes

Quad Mesh

SoQuadMesh Constructs quadrilaterals from the vertices located at the

current coordinates Use the coordinates in order Starting at the index specified by the startIndex field verticesPerColume : number of vertices in the columns VerticesPerRow : number of vertices in the rows


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Complex Shapes

Examples SoQuadMesh *myQuadMesh = new soQuadMesh; myQuadMesh->verticesPerRow = 12 myquadMesh ->VerticesPerColumn = 5

Static float vertexPositions[160][3] = { //1st row

{ } { } { }{ } { } { }{ } { } { }{ } { } { } , // Add 11 rows };

Each row in this quad mesh contains 12 vertices. Each column contains 5

vertices


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Quad Mesh


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Property Nodes

Property classes SoMaterial

Sets ambient, diffuse, specular, emissive color, shininess, transparency

SoDrawStyle Drawing technique to use during rendering

SolightModel Shape nodes show to compute lighting calculations during rend

ering SoEnvironment

Simulate various atmospheric effects (fog, haze, pollution…)


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Property Nodes

Property classes SoShapeHints

Additional information regarding vertex shapes to allow inventor to optimize certain rendering features

SoUnits Define a standard unit of measurement for all subsequent shap

es in the scene graph

All of which are derived from SoNodeEach of these classes affects different elements of the rendering state


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Material Node

SoMaterial node includes the following fields ambientColor(SoMFColor)

Reflected color of an object in response to the ambient lighting in the scene

diffuseColor Object’s base color

specularColor Reflective quality of an Object’s highlights


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Material Node

SoMaterial node includes the following fields emissiveColor

Light produced by an objcet Shininess

Degree of shininess of an object’s surface 0.0 : no shininess

Transparency Degree of transparency of an object’s surface( 0.0 : opaq

ue)


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Material Node

Examples

//set material values SoMaterial *Gold = new soMaterial; Gold -> ambientColor.setValue(.3, .3, .1); Gold ->diffuseColor.setValue(.8, .7, .2); Gold ->specularcolor.setValue(.4, .3, .1); Gold -> shininess = .4; Gold -> transparency = .0; //gold is opaque


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Draw Style Node

SoDrawStyle node include Style

Current drawing style SoDrawStyle::FILLED

Filled regions(default)

SoDrawStyle::LINES Nonfilled outlines

SoDrawStyle::POINTS Points

SoDrawStyle::INVISIBLE Not drawn at all


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Draw Style Node

solid

point

line


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Draw Style Node

SoDrawStyle node include pointSize

radius of points, in printer’s points 0.0 indicates to use the fastest value for rendering

lineWidth Line width in printer’s points Values can range from 0.0 to 256.0

linePattern Line-stipple pattern Values can range from 0 to 0xffff


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Light-Model Node

SoLightModel node includes field Model

Tells the shape node how to compute lighting calculations during rendering

SoLightModel::BASE_COLOR Ignore light source Uses only diffuse color and transparency of the current material

SoLightModel::PHONG Uses the OpenGL Phong lighting model Account all light sources in the scene


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Environment Node

SoEnvironment node Simulate various atmospheric effects – fog, haze, pollution a

nd so on Allows you to specify color, intensity, ambient lighting, many f

actor for fog Includes fields

ambientIntensity intensity of ambient light in the screen Used with phong lighting

attenuation Defines how light drops off the distance from a light source Used with phong lighting


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Environment Node

SoEnvironment node Includes fields

fogType SoEnvironment::NONE SoEnvironment::HAZE

Opacity of the fog Increases linearly with the distance from the camera

SoEnvironment::FOG Opacity of the fog Increases exponentially with the distance fr

om the camera fogColor

Color of the fog


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Shape-Hint Node

Use the SoShapeHints node to notify Inventor It can optimize certain rendering featuresIncludes fields

vertexOrdering Provides hints about the ordering of the faces of a vertex based

shaped derived from SoVertexShape Describes the ordering of all the vertices of all the faces SoShapeHints::COLCKWISE SoShapeHints::COUNTERCLOCKWISE SoShapeHints::UNKNOWN_ORDERING


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Shape-Hint Node

Includes fields shapeType

SoShapeHints::UNKNOWN_SHAPE_TYPE SoShapeHints::SOLID(not an open surface)

Turns on backface culling & turn off two sided lighting

faceType SoShapeHints::UNKNOWN_SHAPE_TYPE SoShapeHints::CONVEX


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Complexity Node

SoComplexity node Amout of subdivision into polygons for subsequent shape no

de in the scene graph Three fields

Type General type of complexity SoComplexity::SCREEN_SPACE SoComplexity::OBJECT_SPACE

Value Provides a hint about the amount of subdivision desired

textureQuality Hint about the quality of texture mapping used on the object


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Complexity Node

example

OBJECT_SPACE SCREEN_SPACE


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Units Node

SoUnits node

Define your data in a variety of different units

Acts like a scale node by scaling subsequent shapes into the specified units

SoUnits::METERS SoUnits::CENTIMETERS SoUnits::MILLIMETERS SoUnits::KILOMETERS SoUnits::YARDS


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Binding Nodes

SoMaterialBinding How to bind materials to shapes SoMaterialBinding::DEFAULT

Uses the best binding for each shape SoMaterialBinding::OVERALL

Uses the first current material for the entire shape SoMaterialBinding::PER_PART

Binds one material to each part in the shape SoMaterialBinding::PER_PART_INDEXED

Binds one material to each part by index And so on…


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Thinking

If the number of current materials is greater than the number of parts? Simply ignore the extra materials if they’re not

required

If the current material contains fewer values than the binding requires? Cycles through the current values as often as

needed


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Indexed Binding

Use the current material values in a new orderInventor refer to the materials-index field of the shape node(SoIndexdFaceSet, SoIndexedLineSet) PER_FACE_INDEX, PER_VERTEX_INDEX…

Example SoIndexedFaceSet

Material List 0 peach 1 khaki 2 white

Material Index 1, 1, 0, 2


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Indexed Binding

Specify PER_FACE Ignores the materialIndex field, cycles in order Face1 peach (0) Face2 khaki (1) Face3 white (2) Face4 peach (0)

Specify PER_FACE_INDEXED Face1 khaki (1) Face2 khaki (1) Face3 peach(0) Face4 white (2)


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Binding per Vertex

PER_VERTEX Selects materials in order from the materials list

PER_VERTEX_INDEXED Selects materials in order from the materials index


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Normal Binding

SoNormalBinding node Type of normal binding specified Hint to the shape node about how to apply the current normal

s to that shape

SoIndexedFaceSet, SoIndexedTriangleStripSet Contain a normalIndex field normalIndex field store indices into the normals list Ginding specifed does not require indices, the normalindex fi

eld is not used

Indexed normals do not cycle


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Generating normals Automatically

SoVertexShape Normals can be generated automatically for any shape derive

d

Generating normals DEFAULT normal binding is used Do not specify any normals The number of normals is different from the number of vertic

es


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Transformations

Cumulative effect on the current geometric transformationSoTransform Node Translation

Translation in x, y, z Rotation

Rotation in terms of an axis and angle : x, y, z, angle scaleFactor

Scaling factor in x, y, z ScaleOrientation

Ratation to apply before the scale is applied Center

Center point for rotation and scaling


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Order of Transformations

Last field in the node affects the shape object first

The groups with transformations in different order


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Order of Transformations

Effects of ordering transformation

shapes properties binding 2001.08.14 chung ji hye

Documents

complex shapesfacesetsofaceset

triangle stripset face

shape hintsmaterial

shape noderepresents

subsequent shape

vertex shapes

number of vertices

shapesall shape nodes