gov.nasa.worldwind.render
Class SurfaceObjectTileBuilder

java.lang.Object
  gov.nasa.worldwind.render.SurfaceObjectTileBuilder

public class SurfaceObjectTileBuilder
extends Object

Builds a list of SurfaceTile instances who's content is defined by a specified set of SurfaceObject references. It's typically not necessary to use SurfaceObjectTileBuilder directly. World Wind's default SceneController automatically batches instances of SurfaceObject in a single SurfaceObjectTileBuilder. Applications that need to draw basic surface shapes should use or extend SurfaceShape instead of using SurfaceObjectTileBuilder directly.

Surface tiles are built by calling buildTiles(DrawContext, Iterable) (DrawContext, Iterable)} with an Iterable of SurfaceObjects. This assembles a set of surface tiles that meet the resolution requirements for the specified draw context, then draws the SurfaceObjects into those offscreen surface tiles by calling SurfaceObject.render(DrawContext). This process may temporarily use the framebuffer to perform offscreen rendering, and therefore should be called during the preRender method of a World Wind Layer. See PreRenderable for details. Once built, the surface tiles can be rendered by a SurfaceTileRenderer.

By default, SurfaceObjectTileBuilder creates texture tiles with a width and height of 512 pixels, and with internal format GL_RGBA. These parameters are configurable by calling setTileDimension(java.awt.Dimension) or setTileTextureFormat(int).

The most common usage pattern for SurfaceObjectTileBuilder is to build the surface tiles from a set of SurfaceObjects during the preRender phase, then draw those surface tiles during the render phase. For example, a Renderable can use SurfaceObjectTileBuilder to draw a set of SurfaceObjects as follows:

 class MyRenderable implements Renderable, PreRenderable
 {
     protected SurfaceObjectTileBuilder tileBuilder = new SurfaceObjectTileBuilder();
     protected ArrayList tiles = new ArrayList();

     public void preRender(DrawContext dc)
     {
         List surfaceObjects = Arrays.asList(
             new SurfaceCircle(LatLon.fromDegrees(0, 100), 10000),
             new SurfaceSquare(LatLon.fromDegrees(0, 101), 10000));
         this.tiles.addAll(this.tileBuilder.buildSurfaceTiles(dc, surfaceObjects));
     }

     public void render(DrawContext dc)
     {
         dc.getGeographicSurfaceTileRenderer().renderTiles(dc, this.tiles);
     }
 }
 

Nested Class Summary

protected static class	SurfaceObjectTileBuilder.SurfaceObjectTile Represents a TextureTile who's contents is constructed by a set of surface objects.
protected static class	SurfaceObjectTileBuilder.SurfaceObjectTileStateKey Represents a surface object tile's current state.

Field Summary

protected List<SurfaceObject>	currentSurfaceObjects List of currently assembled surface objects.
protected Dimension	currentTileDimension Indicates the currently used tile texture width and height, in pixels.
protected List<SurfaceObjectTileBuilder.SurfaceObjectTile>	currentTiles List of currently assembled surface tiles.
protected static LatLon	DEFAULT_LEVEL_ZERO_TILE_DELTA The default level zero tile delta used to construct a LevelSet.
protected static int	DEFAULT_NUM_LEVELS The default number of levels used to construct a LevelSet.
protected static double	DEFAULT_SPLIT_SCALE The default split scale.
protected static int	DEFAULT_TEXTURE_DIMENSION The default surface tile texture dimension, in pixels.
protected static int	DEFAULT_TEXTURE_INTERNAL_FORMAT The default OpenGL internal format used to create surface tile textures.
protected static int	DEFAULT_TEXTURE_PIXEL_FORMAT The default OpenGL pixel format used to create surface tile textures.
protected static Map<Dimension,LevelSet>	levelSetMap Map associating a tile texture dimension to its corresponding LevelSet.
protected static long	nextUniqueId The next unique ID.
protected OGLRenderToTextureSupport	rttSupport Support class used to render to an offscreen surface tile.
protected double	splitScale Controls the tile resolution as distance changes between the globe's surface and the eye point.
protected Map<Dimension,String>	tileCacheNameMap Map associating a tile texture dimension to a tile cache name.
protected Dimension	tileDimension Indicates the desired tile texture width and height, in pixels.
protected int	tileTextureFormat The surface tile OpenGL texture format.
protected boolean	useLinearFilter Controls if surface tiles are rendered using a linear filter or a nearest-neighbor filter.
protected boolean	useMipmaps Controls if mip-maps are generated for surface tile textures.

Constructor Summary

SurfaceObjectTileBuilder()
Constructs a new SurfaceObjectTileBuilder with a tile width and height of 512, with the default tile texture format, with linear filtering enabled, and with mip-mapping disabled.

SurfaceObjectTileBuilder(Dimension tileTextureDimension, int tileTextureFormat, boolean useLinearFilter, boolean useMipmaps)
Constructs a new SurfaceObjectTileBuilder width the specified tile dimension, tile texture format, and flags specifying if linear filtering and mip-mapping are enabled.

Method Summary

protected void	addIntersectingObjects(DrawContext dc, SurfaceObjectTileBuilder.SurfaceObjectTile parent, SurfaceObjectTileBuilder.SurfaceObjectTile tile) Adds SurfaceObjects from the parent's object list to the specified tile's object list.
protected void	addTile(SurfaceObjectTileBuilder.SurfaceObjectTile tile) Adds the specified tile to the tile builder's currentTiles list.
protected void	addTileOrDescendants(DrawContext dc, LevelSet levelSet, SurfaceObjectTileBuilder.SurfaceObjectTile parent, SurfaceObjectTileBuilder.SurfaceObjectTile tile) Potentially adds the specified tile or its descendants to the tile builder's currentTiles list.
protected void	assembleSurfaceObjects(Iterable<?> iterable) Adds any SurfaceObjects in the specified Iterable to the tile builder's currentSurfaceObjects list.
protected void	assembleTiles(DrawContext dc) Assembles a set of surface tiles that are visible in the specified DrawContext and meet the tile builder's resolution criteria.
List<SurfaceTile>	buildTiles(DrawContext dc, Iterable<?> iterable) Assembles the surface tiles and draws any SurfaceObjects in the iterable into those offscreen tiles.
protected boolean	canAssembleTiles(DrawContext dc) Returns true if the draw context's viewport width and height are greater than zero.
protected Dimension	computeTextureTileDimension(DrawContext dc) Returns the tile dimension used to create the tile textures for the specified DrawContext.
protected static LevelSet	createLevelSet(int tileWidth, int tileHeight) Returns a new LevelSet with the specified tile width and height.
protected Object	createSurfaceTileDrawContext(SurfaceObjectTileBuilder.SurfaceObjectTile tile) Returns a new Object representing the drawing context for the specified tile.
protected SurfaceObjectTileBuilder.SurfaceObjectTile	createTile(Sector sector, Level level, int row, int column, String cacheName) Returns a new SurfaceObjectTile corresponding to the specified sector, level, row, column, and cacheName.
protected Object	createTileKey(Level level, int row, int column, String cacheName) Returns a new tile key corresponding to the tile with the specified level, row, column, and cacheName.
protected Texture	createTileTexture(DrawContext dc, int width, int height) Returns a new surface tile texture for use on the specified draw context with the specified width and height.
protected LevelSet	getLevelSet(Dimension tileDimension) Returns a shared LevelSet for the specified tileDimension.
double	getSplitScale() Returns the split scale value controlling the tile's surface texel resolution relative to the distance between the globe's surface at the image position and the eye point.
protected String	getTileCacheName(Dimension tileDimension) Indicates the tile cache name to use for the specified tileDimension.
Dimension	getTileDimension() Returns the surface tile dimension.
int	getTileTextureFormat() Returns the surface tile's OpenGL texture format, or 0 to indicate that the default format is used.
protected boolean	intersectsFrustum(DrawContext dc, TextureTile tile) Test if the tile intersects the specified draw context's frustum.
protected boolean	intersectsVisibleSector(DrawContext dc, TextureTile tile) Test if the specified tile intersects the draw context's visible sector.
boolean	isUseLinearFilter() Returns if linear filtering is used when rendering surface tiles.
boolean	isUseMipmaps() Returns if mip-maps are generated for surface tile textures.
protected boolean	meetsRenderCriteria(DrawContext dc, LevelSet levelSet, Tile tile) Tests if the specified tile meets the rendering criteria on the specified draw context.
protected boolean	needToSplit(DrawContext dc, Tile tile) Tests if the specified tile must be split to meets the desired resolution on the specified draw context.
protected String	nextCacheName() Returns a unique name appropriate for use as part of a cache name.
protected static long	nextUniqueId() Returns the next unique integer associated with a SurfaceObjectTileBuilder.
void	setSplitScale(double splitScale) Sets the parameter controlling the tile resolution as distance changes between the globe's surface and the eye point.
void	setTileDimension(Dimension dimension) Specifies the preferred surface tile texture dimension.
void	setTileTextureFormat(int textureFormat) Specifies the surface tile's OpenGL texture format.
void	setUseLinearFilter(boolean useLinearFilter) Specifies if linear filtering should be used when rendering surface tiles.
void	setUseMipmaps(boolean useMipmaps) Specifies if mip-maps should be generated for surface tile textures.
protected void	updateTile(DrawContext dc, SurfaceObjectTileBuilder.SurfaceObjectTile tile) Draws the current list of SurfaceObjects into the specified surface tile.
protected void	updateTiles(DrawContext dc) Updates each SurfaceObjectTileBuilder.SurfaceObjectTile in the currentTiles list.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

currentSurfaceObjects

protected List<SurfaceObject> currentSurfaceObjects

List of currently assembled surface objects. Used during tile assembly and updating.

currentTileDimension

protected Dimension currentTileDimension

Indicates the currently used tile texture width and height, in pixels. This is different than the caller specified tileDimension if this value does not fit in the viewport, or is not a power of two. Initially null.

currentTiles

protected List<SurfaceObjectTileBuilder.SurfaceObjectTile> currentTiles

List of currently assembled surface tiles.

DEFAULT_LEVEL_ZERO_TILE_DELTA

protected static final LatLon DEFAULT_LEVEL_ZERO_TILE_DELTA

The default level zero tile delta used to construct a LevelSet.

DEFAULT_NUM_LEVELS

protected static final int DEFAULT_NUM_LEVELS

The default number of levels used to construct a LevelSet. Approximately 0.1 meters per pixel at the Earth's equator.

See Also:

Constant Field Values

DEFAULT_SPLIT_SCALE

protected static final double DEFAULT_SPLIT_SCALE

The default split scale. The split scale 2.9 has been empirically determined to render sharp lines and edges with the SurfaceShapes such as SurfacePolyline and SurfacePolygon.

See Also:

Constant Field Values

DEFAULT_TEXTURE_DIMENSION

protected static final int DEFAULT_TEXTURE_DIMENSION

The default surface tile texture dimension, in pixels.

See Also:

Constant Field Values

DEFAULT_TEXTURE_INTERNAL_FORMAT

protected static final int DEFAULT_TEXTURE_INTERNAL_FORMAT

The default OpenGL internal format used to create surface tile textures.

See Also:

Constant Field Values

DEFAULT_TEXTURE_PIXEL_FORMAT

protected static final int DEFAULT_TEXTURE_PIXEL_FORMAT

The default OpenGL pixel format used to create surface tile textures.

See Also:

Constant Field Values

levelSetMap

protected static Map<Dimension,LevelSet> levelSetMap

Map associating a tile texture dimension to its corresponding LevelSet. This map is a class property in order to share LevelSets across all instances of SurfaceObjectTileBuilder.

nextUniqueId

protected static long nextUniqueId

The next unique ID. This property is shared by all instances of SurfaceObjectTileBuilder.

rttSupport

protected OGLRenderToTextureSupport rttSupport

Support class used to render to an offscreen surface tile.

splitScale

protected double splitScale

Controls the tile resolution as distance changes between the globe's surface and the eye point.

tileCacheNameMap

protected Map<Dimension,String> tileCacheNameMap

Map associating a tile texture dimension to a tile cache name. This map is an instance property so that the cache names for each instance and each tile dimension are unique.

tileDimension

protected Dimension tileDimension

Indicates the desired tile texture width and height, in pixels. Initially set to DEFAULT_TEXTURE_DIMENSION.

tileTextureFormat

protected int tileTextureFormat

The surface tile OpenGL texture format. 0 indicates the default format is used.

useLinearFilter

protected boolean useLinearFilter

Controls if surface tiles are rendered using a linear filter or a nearest-neighbor filter.

useMipmaps

protected boolean useMipmaps

Controls if mip-maps are generated for surface tile textures.

Constructor Detail

SurfaceObjectTileBuilder

public SurfaceObjectTileBuilder()

Constructs a new SurfaceObjectTileBuilder with a tile width and height of 512, with the default tile texture format, with linear filtering enabled, and with mip-mapping disabled.

SurfaceObjectTileBuilder

public SurfaceObjectTileBuilder(Dimension tileTextureDimension,
                                int tileTextureFormat,
                                boolean useLinearFilter,
                                boolean useMipmaps)

Constructs a new SurfaceObjectTileBuilder width the specified tile dimension, tile texture format, and flags specifying if linear filtering and mip-mapping are enabled.

Parameters:

tileTextureDimension - the surface tile texture dimension, in pixels.

tileTextureFormat - the surface tile OpenGL texture format, or 0 to use the default format.

useLinearFilter - true to use linear filtering while rendering surface tiles; false to use nearest-neighbor filtering.

useMipmaps - true to generate mip-maps for surface tile textures; false otherwise.

Throws:

IllegalArgumentException - if the tile dimension is null.

Method Detail

addIntersectingObjects

protected void addIntersectingObjects(DrawContext dc,
                                      SurfaceObjectTileBuilder.SurfaceObjectTile parent,
                                      SurfaceObjectTileBuilder.SurfaceObjectTile tile)

Adds SurfaceObjects from the parent's object list to the specified tile's object list. If the tile's sector does not intersect the sector bounding the parent's object list, this does nothing. Otherwise, this adds any of the parent's SurfaceObjects that intersect the tile's sector to the tile's object list.

Parameters:

dc - the current DrawContext.

parent - the tile's parent.

tile - the tile to add intersecting SurfaceObject to.

addTile

protected void addTile(SurfaceObjectTileBuilder.SurfaceObjectTile tile)

Adds the specified tile to the tile builder's currentTiles list.

Parameters:

tile - the tile to add.

addTileOrDescendants

protected void addTileOrDescendants(DrawContext dc,
                                    LevelSet levelSet,
                                    SurfaceObjectTileBuilder.SurfaceObjectTile parent,
                                    SurfaceObjectTileBuilder.SurfaceObjectTile tile)

Potentially adds the specified tile or its descendants to the tile builder's currentTiles list. The tile and its descendants are discarded if the tile is not visible or does not intersect any SurfaceObjects in the parent's surface object list. See SurfaceObjectTileBuilder.SurfaceObjectTile.getObjectList().

If the tile meet the tile builder's resolution criteria it's added to the tile builder's currentTiles list. Otherwise, it's split into four sub-tiles and each tile is recursively processed. See meetsRenderCriteria(DrawContext, gov.nasa.worldwind.util.LevelSet, gov.nasa.worldwind.util.Tile).

Parameters:

dc - the current DrawContext.

levelSet - the tile's LevelSet.

parent - the tile's parent, or null if the tile is a top level tile.

tile - the tile to add.

assembleSurfaceObjects

protected void assembleSurfaceObjects(Iterable<?> iterable)

Adds any SurfaceObjects in the specified Iterable to the tile builder's currentSurfaceObjects list.

Parameters:

iterable - the Iterable to gather SurfaceObjects from.

assembleTiles

protected void assembleTiles(DrawContext dc)

Assembles a set of surface tiles that are visible in the specified DrawContext and meet the tile builder's resolution criteria. Tiles are culled against the current SurfaceObject list, against the DrawContext's view frustum during rendering mode, and against the DrawContext's pick frustums during picking mode. If a tile does not meet the tile builder's resolution criteria, it's split into four sub-tiles and the process recursively repeated on the sub-tiles. Visible leaf tiles are added to the currentTiles list.

During assembly each SurfaceObject in currentSurfaceObjects is sorted into the tiles they intersect. The top level tiles are used as an index to quickly determine which tiles each SurfaceObjects intersects. SurfaceObjects are sorted into sub-tiles by simple intersection tests. SurfaceObjects are added to each tile's surface object list at most once. See SurfaceObjectTileBuilder.SurfaceObjectTile.addSurfaceObject(SurfaceObject, gov.nasa.worldwind.geom.Sector). Tiles that don't intersect any SurfaceObjects are discarded.

Parameters:

dc - the DrawContext to assemble tiles for.

buildTiles

public List<SurfaceTile> buildTiles(DrawContext dc,
                                    Iterable<?> iterable)

Assembles the surface tiles and draws any SurfaceObjects in the iterable into those offscreen tiles. The surface tiles are assembled to meet the necessary resolution of to the draw context's View. This may temporarily use the framebuffer to perform offscreen rendering, and therefore should be called during the preRender method of a World Wind Layer.

This returns an empty List if the specified iterable is null, is empty or contains no SurfaceObjects.

Parameters:

dc - the draw context to build tiles for.

iterable - the iterable to gather SurfaceObjects from.

Returns:

a List of SurfaceTiles containing a composite representation of the specified SurfaceObjects.

Throws:

IllegalArgumentException - if the draw context is null.

canAssembleTiles

protected boolean canAssembleTiles(DrawContext dc)

Returns true if the draw context's viewport width and height are greater than zero.

Parameters:

dc - the DrawContext to test.

Returns:

true if the DrawContext's has a non-zero viewport; false otherwise.

computeTextureTileDimension

protected Dimension computeTextureTileDimension(DrawContext dc)

Returns the tile dimension used to create the tile textures for the specified DrawContext. This attempts to use the caller configured tileDimension, but always returns a dimension that is is a power of two, is square, and fits in the DrawContext's viewport.

Parameters:

dc - the DrawContext to compute a texture tile dimension for.

Returns:

a texture tile dimension appropriate for the specified DrawContext.

createLevelSet

protected static LevelSet createLevelSet(int tileWidth,
                                         int tileHeight)

Returns a new LevelSet with the specified tile width and height. The LevelSet overs the full sphere, has a level zero tile delta of DEFAULT_LEVEL_ZERO_TILE_DELTA, has number of levels equal to DEFAULT_NUM_LEVELS (with no empty levels). The LevelSets' cache name and dataset name dummy values, and should not be used.

Parameters:

tileWidth - the LevelSet's tile width, in pixels.

tileHeight - the LevelSet's tile height, in pixels.

Returns:

a new LevelSet configured to with

createSurfaceTileDrawContext

protected Object createSurfaceTileDrawContext(SurfaceObjectTileBuilder.SurfaceObjectTile tile)

Returns a new Object representing the drawing context for the specified tile. The returned object should represent the tile's sector and it's corresponding viewport in pixels.

Parameters:

tile - The tile to create a context for.

Returns:

a new drawing context for the specified tile.

createTile

protected SurfaceObjectTileBuilder.SurfaceObjectTile createTile(Sector sector,
                                                                Level level,
                                                                int row,
                                                                int column,
                                                                String cacheName)

Returns a new SurfaceObjectTile corresponding to the specified sector, level, row, column, and cacheName.

Parameters:

sector - The tile's Sector.

level - The tile's Level in a LevelSet.

row - The tile's row in the Level, starting from 0 and increasing to the right.

column - The tile's column in the Level, starting from 0 and increasing upward.

cacheName - Tile tile's cache name.

Returns:

a new SurfaceObjectTile.

createTileKey

protected Object createTileKey(Level level,
                               int row,
                               int column,
                               String cacheName)

Returns a new tile key corresponding to the tile with the specified level, row, column, and cacheName.

Parameters:

level - The tile's Level in a LevelSet.

row - The tile's row in the Level, starting from 0 and increasing to the right.

column - The tile's column in the Level, starting from 0 and increasing upward.

cacheName - Tile tile's cache name.

Returns:

a tile key.

createTileTexture

protected Texture createTileTexture(DrawContext dc,
                                    int width,
                                    int height)

Returns a new surface tile texture for use on the specified draw context with the specified width and height.

The returned texture's internal format is specified by tilePixelFormat. If tilePixelFormat is zero, this returns a texture with internal format GL_RGBA8.

The returned texture's parameters are configured as follows:

Parameters:

dc - the draw context to create a texture for.

width - the texture's width, in pixels.

height - the texture's height, in pixels.

Returns:

a new texture with the specified width and height.

getLevelSet

protected LevelSet getLevelSet(Dimension tileDimension)

Returns a shared LevelSet for the specified tileDimension. All instances of SurfaceObjectTileBuilder share common LevelSets to determine which tiles are visible, but create unique tile instances and uses a unique tile cache name. Since all instances use the same tile structure to determine visible tiles, this saves memory while ensuring that each instance stores its own tiles in the cache.

The returned LevelSet's cache name and dataset name are dummy values, and should not be used. Use this tile builder's cache name for the specified tileDimension instead.

In practice, there are at most 10 dimensions we use: 512, 256, 128, 64, 32, 16, 8, 4, 2, 1. Therefore keeping the LevelSets in a map requires little memory overhead, and ensures each LevelSet is retained once constructed. Retaining references to the LevelSets means we're able to re-use the texture resources associated with each LevelSet in the DrawContext's texture cache.

Subsequent calls are guaranteed to return the same LevelSet for the same tileDimension.

Parameters:

tileDimension - the DrawContext to return a LevelSet for.

Returns:

a LevelSet who's tile dimension fits in the DrawContext's viewport.

getSplitScale

public double getSplitScale()

Returns the split scale value controlling the tile's surface texel resolution relative to the distance between the globe's surface at the image position and the eye point.

Returns:

the current split scale.

See Also:

setSplitScale(double)

getTileCacheName

protected String getTileCacheName(Dimension tileDimension)

Indicates the tile cache name to use for the specified tileDimension. The cache name is unique to this SurfaceObjectTileBuilder and the tileDimension. Using a unique cache name for each instance and tile dimension ensures that the tiles for this instances and tileDimension do not conflict with any other tiles in the cache.

In practices, there are at most 10 dimensions we'll use (512, 256, 128, 64, 32, 16, 8, 4, 2, 1 ), and therefore at most 10 cache names for each SurfaceObjectTileBuilder.

Subsequent calls are guaranteed to return the same cache name for the same tileDimension.

Parameters:

tileDimension - the texture tile dimension who's cache name is returned.

Returns:

the tile cache name for the specified tileDimension

getTileDimension

public Dimension getTileDimension()

Returns the surface tile dimension.

Returns:

the surface tile dimension, in pixels.

getTileTextureFormat

public int getTileTextureFormat()

Returns the surface tile's OpenGL texture format, or 0 to indicate that the default format is used.

Returns:

the OpenGL texture format, or 0 if the default format is used.

See Also:

setTileTextureFormat(int)

intersectsFrustum

protected boolean intersectsFrustum(DrawContext dc,
                                    TextureTile tile)

Test if the tile intersects the specified draw context's frustum. During picking mode, this tests intersection against all of the draw context's pick frustums. During rendering mode, this tests intersection against the draw context's viewing frustum.

Parameters:

dc - the draw context the SurfaceObject is related to.

tile - the tile to test for intersection.

Returns:

true if the tile intersects the draw context's frustum; false otherwise.

intersectsVisibleSector

protected boolean intersectsVisibleSector(DrawContext dc,
                                          TextureTile tile)

Test if the specified tile intersects the draw context's visible sector. This returns false if the draw context's visible sector is null.

Parameters:

dc - the current draw context.

tile - the tile to test for intersection.

Returns:

true if the tile intersects the draw context's visible sector; false otherwise.

isUseLinearFilter

public boolean isUseLinearFilter()

Returns if linear filtering is used when rendering surface tiles.

Returns:

true if linear filtering is used; false if nearest-neighbor filtering is used.

isUseMipmaps

public boolean isUseMipmaps()

Returns if mip-maps are generated for surface tile textures.

Returns:

true if mip-maps are generated; false otherwise.

meetsRenderCriteria

protected boolean meetsRenderCriteria(DrawContext dc,
                                      LevelSet levelSet,
                                      Tile tile)

Tests if the specified tile meets the rendering criteria on the specified draw context. This returns true if the tile is from the level set's final level, or if the tile achieves the desired resolution on the draw context.

Parameters:

dc - the current draw context.

levelSet - the level set the tile belongs to.

tile - the tile to test.

Returns:

true if the tile meets the rendering criteria; false otherwise.

needToSplit

protected boolean needToSplit(DrawContext dc,
                              Tile tile)

Tests if the specified tile must be split to meets the desired resolution on the specified draw context. This compares the distance form the eye point to the tile to determine if the tile meets the desired resolution for the View attached to the draw context.

Parameters:

dc - the current draw context.

tile - the tile to test.

Returns:

true if the tile must be split; false otherwise.

nextCacheName

protected String nextCacheName()

Returns a unique name appropriate for use as part of a cache name. The returned string is constructed as follows: this.getClass().getName() + "/" + nextUniqueId().

Returns:

a unique cache name.

nextUniqueId

protected static long nextUniqueId()

Returns the next unique integer associated with a SurfaceObjectTileBuilder. This method is synchronized to ensure that two threads calling simultaneously receive different IDs. Since this method is called from SurfaceObjectTileBuilder's constructor, this is critical to ensure that SurfaceObjectTileBuilders can be safely constructed on separate threads.

Returns:

the next unique integer.

setSplitScale

public void setSplitScale(double splitScale)

Sets the parameter controlling the tile resolution as distance changes between the globe's surface and the eye point. Higher resolution is displayed as the split scale increases from 1.0. Lower resolution is displayed as the split scale decreases from 1.0. The default value is 2.9.

Parameters:

splitScale - a value near 1.0 that controls the tile's surface texel resolution as the distance between the globe's surface and the eye point change. Increasing values select higher resolution, decreasing values select lower resolution. The default value is 2.9.

setTileDimension

public void setTileDimension(Dimension dimension)

Specifies the preferred surface tile texture dimension. If the dimension is larger than the viewport dimension, this uses a dimension with width and height set to the largest power of two that is less than or equal to the specified dimension and the viewport dimension.

Parameters:

dimension - the surface tile dimension, in pixels.

Throws:

IllegalArgumentException - if the dimension is null.

setTileTextureFormat

public void setTileTextureFormat(int textureFormat)

Specifies the surface tile's OpenGL texture format. A value of 0 indicates that the default format should be used. Otherwise, the texture format may be one of the following:

• GL_ALPHA
• GL_ALPHA4
• GL_ALPHA8
• GL_ALPHA12
• GL_ALPHA16
• GL_COMPRESSED_ALPHA
• GL_COMPRESSED_LUMINANCE
• GL_COMPRESSED_LUMINANCE_ALPHA
• GL_COMPRESSED_INTENSITY
• GL_COMPRESSED_RGB
• GL_COMPRESSED_RGBA
• GL_DEPTH_COMPONENT
• GL_DEPTH_COMPONENT16
• GL_DEPTH_COMPONENT24
• GL_DEPTH_COMPONENT32
• GL_LUMINANCE
• GL_LUMINANCE4
• GL_LUMINANCE8
• GL_LUMINANCE12
• GL_LUMINANCE16
• GL_LUMINANCE_ALPHA
• GL_LUMINANCE4_ALPHA4
• GL_LUMINANCE6_ALPHA2
• GL_LUMINANCE8_ALPHA8
• GL_LUMINANCE12_ALPHA4
• GL_LUMINANCE12_ALPHA12
• GL_LUMINANCE16_ALPHA16
• GL_INTENSITY
• GL_INTENSITY4
• GL_INTENSITY8
• GL_INTENSITY12
• GL_INTENSITY16
• GL_R3_G3_B2
• GL_RGB
• GL_RGB4
• GL_RGB5
• GL_RGB8
• GL_RGB10
• GL_RGB12
• GL_RGB16
• GL_RGBA
• GL_RGBA2
• GL_RGBA4
• GL_RGB5_A1
• GL_RGBA8
• GL_RGB10_A2
• GL_RGBA12
• GL_RGBA16
• GL_SLUMINANCE
• GL_SLUMINANCE8
• GL_SLUMINANCE_ALPHA
• GL_SLUMINANCE8_ALPHA8
• GL_SRGB
• GL_SRGB8
• GL_SRGB_ALPHA
• GL_SRGB8_ALPHA8

If the texture format is any of GL_RGB, GL_RGB8, GL_RGBA, or GL_RGBA8, the tile builder attempts to use OpenGL framebuffer objects to render shapes to the texture tiles. Otherwise, this renders shapes to the framebuffer and copies the framebuffer contents to the texture tiles.

Parameters:

textureFormat - the OpenGL texture format, or 0 to use the default format.

setUseLinearFilter

public void setUseLinearFilter(boolean useLinearFilter)

Specifies if linear filtering should be used when rendering surface tiles.

Parameters:

useLinearFilter - true to use linear filtering; false to use nearest-neighbor filtering.

setUseMipmaps

public void setUseMipmaps(boolean useMipmaps)

Specifies if mip-maps should be generated for surface tile textures.

Parameters:

useMipmaps - true to generate mip-maps; false otherwise.

updateTile

protected void updateTile(DrawContext dc,
                          SurfaceObjectTileBuilder.SurfaceObjectTile tile)

Draws the current list of SurfaceObjects into the specified surface tile. The surface tiles is updated only when necessary. The tile keeps track of the list of SurfaceObjects rendered into it, and the state keys those objects. The tile is updated if the list changes, if any of the state keys change, or if the tile has no texture. Otherwise the tile is left unchanged and the update is skipped.

Parameters:

dc - the draw context the tile relates to.

tile - the tile to update.

updateTiles

protected void updateTiles(DrawContext dc)

Updates each SurfaceObjectTileBuilder.SurfaceObjectTile in the currentTiles list. This is typically called after assembleTiles(DrawContext) to update the assembled tiles.

This method does nothing if currentTiles is empty.

Parameters:

dc - the draw context the tiles relate to.