vtAbstractLayer Class Reference

Inheritance diagram for vtAbstractLayer:

Public Member Functions
void	CreateFeatureVisuals (osg::Group *pParent, vtHeightField3d *pHF, float fSpacing, bool progress_callback(int)=NULL)
void	CreateLineGeometryForPoints ()
void	CreateObjectGeometry (uint iIndex)
void	CreateLineGeometry (uint iIndex)
void	CreateFeatureLabel (uint iIndex)
void	ReleaseGeometry ()
void	ReleaseFeatureGeometry (vtFeature *f)
Public Member Functions inherited from vtLayer
void	SetProps (const vtTagArray &props)
	Set the properties for this layer, which includes style.
vtTagArray &	Props ()
	Get the properties for this layer, which includes style.

Protected Attributes
vtFeatureSet *	m_pSet
	This is the set of features which the layer contains.

Detailed Description

An abstract layer is a traditional GIS-style set of geometry features with attributes. It can be shown on the terrain in a variety of ways (styles). Style is described with a set of properties, encoded as a vtTagArray. These are the supported style properties, all of which are optional:

• "Filename": If the layer should be loaded from disk, this is the filename to load from. It can be a relative path anywhere on the VTP data paths, or an absolute path.
• "ObjectGeometry": true to show geometry for each point of the features.
  • "ObjectGeomColor": The color of each geometry (R,G,B as float 0..1). Default is white.
  • "ObjectColorFieldIndex": The 0-based index of the field which contains the color of each geometry.
  • "ObjectGeomHeight": The height in meters of each geometry above the ground.
  • "ObjectGeomSize": The size in meters of each geometry.
• "LineGeometry": true to show lines running though each point of the features.
  • "LineGeomColor": The color of each line (R,G,B as float 0..1). Default is white.
  • "LineColorFieldIndex": The 0-based index of the field which contains the color of each line.
  • "LineGeomHeight": The height in meters of each line above the ground.
  • "LineWidth": Pixel width of the 3D lines to create. Default it 1.
  • "Tessellate": true to tesslate the geometry of each feature before draping it on the ground. This can produce a smoother result.
• "Labels": true to show floating text labels for the features.
  • "LabelColor": The color of each label (R,G,B as float 0..1) Default is white.
  • "TextColorFieldIndex": The 0-based index of the field which contains the color of each label.
  • "TextFieldIndex": The 0-based index of the field which contains the text you want to use for the label. For example, if you have several fields called "ID", "Name", and "Address", and you want to show "Name", use the value 1.
  • "LabelHeight": Height in meters above the ground. This is the distance from the ground surface to the lower edge of the text label. Default is 0.
  • "LabelSize": Size (vertical extent) of the text labels in meters. Default is 18.
  • "Font": Filename (may include path) of the font to use for text labels. Example: "Arial.ttf"
  • "LabelOutline": true to put a dark outline around the font to improve its readability against most backgrounds.

When a terrain description (TParams) contains an abstract layer, these same style properties are encoded. On disk, they are stored as XML elements.

Member Function Documentation

void vtAbstractLayer::CreateFeatureLabel

(

uint

iIndex

)

Given a featureset and style description, create a labels and place it on the terrain.

If the features are 2D or 3D points (vtFeatureSetPoint2D or vtFeatureSetPoint3D) then the labels will be placed at those points. If the features are 2D polygons (vtFeatureSetPolygon) then the point used is the centroid of the polygon.

void vtAbstractLayer::CreateFeatureVisuals	(	osg::Group *	pParent,
		vtHeightField3d *	pHF,
		float	fSpacing,
		bool	progress_callbackint = NULL
	)

Given a featureset, create the geometry and place it on the terrain.

void vtAbstractLayer::CreateLineGeometry

(

uint

iIndex

)

Given a featureset and style description, create line geometry. If 2D, it will be draped on the terrain. Polygon features (vtFeatureSetPolygon) will also be created as line geometry (unfilled polygons) and draped on the ground.

void vtAbstractLayer::CreateLineGeometryForPoints

(

)

Given a featureset and style description, create line geometry that goes through all the points.

void vtAbstractLayer::CreateObjectGeometry

(

uint

iIndex

)

Given a featureset and style description, create a geometry object (such as spheres) and place it on the terrain. If 2D, they will be draped on the terrain.

void vtAbstractLayer::ReleaseFeatureGeometry

(

vtFeature *

f

)

Release all the 3D stuff created for a given feature.

void vtAbstractLayer::ReleaseGeometry

(

)

Release all the 3D stuff created for the layer (including geometry and labels).