gov.nasa.worldwind.util

Class GLUTessellatorSupport

java.lang.Object

gov.nasa.worldwind.util.GLUTessellatorSupport

public class GLUTessellatorSupport
extends Object

GLUTessellatorSupport is a utility class for configuring and using a GLUtessellator to tessellate complex polygons into triangles.

The standard pattern for using GLUTessellatorSupport to prepare a GLUtessellator is as follows: GLUTessellatorSupport glts = new GLUTessellatorSupport();
GLUtessellatorCallback cb = ...; // Reference to an implementation of GLUtessellatorCallback.
Vec4 normal = new Vec4(0, 0, 1); // The polygon's normal. This example shows an appropriate normal for tessellating x-y coordinates.


glts.beginTessellation(cb, new Vec4(0, 0, 1));
try
{
GLUtessellator tess = glts.getGLUtessellator();
}
finally
{
glts.endTessellation();
}


Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GLUTessellatorSupport.CollectIndexListsCallback Provides the callback class used to capture the shapes determined by the tessellator.
static class	GLUTessellatorSupport.CollectPrimitivesCallback Provides the callback class used to capture triangle and line primitive indices determined by the tessellator.
protected static class	GLUTessellatorSupport.OGLDrawPrimitivesCallback
static class	GLUTessellatorSupport.RecursiveCallback Recursively forwards boundary tessellation results from one GLU tessellator to another.
static class	GLUTessellatorSupport.VertexData Provides a container for associating a tessellator's vertex with its index and application-specified edge flag.

Field Summary

Fields

Modifier and Type	Field and Description
protected GLUtessellator	tess

Constructor Summary

Constructors

Constructor and Description
GLUTessellatorSupport() Creates a new GLUTessellatorSupport, but otherwise does nothing.

Method Summary

Modifier and Type	Method and Description
void	beginTessellation(GLUtessellatorCallback callback, Vec4 normal) Prepares this GLUTessellatorSupport's internal GLU tessellator for use.
static String	convertGLUTessErrorToString(int errno) Converts the specified GLU tessellator error number to a string description.
static GLUtessellatorCallback	createOGLDrawPrimitivesCallback(GL2 gl) Creates a new GLUtessellatorCallback that draws tessellated polygons as OpenGL primitives by calling glBegin, glEnd, and glVertex.
void	endTessellation() Frees any GLU resources used by this GLUTessellatorSupport, and invalidates this instance's internal GLU tessellator.
GLUtessellator	getGLUtessellator() Returns this GLUTessellatorSupport's internal GLUtessellator instance.

Methods inherited from class java.lang.Object

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

Field Detail

tess

protected GLUtessellator tess

Constructor Detail

GLUTessellatorSupport

public GLUTessellatorSupport()

Creates a new GLUTessellatorSupport, but otherwise does nothing.

Method Detail

beginTessellation

public void beginTessellation(GLUtessellatorCallback callback,
                              Vec4 normal)

Prepares this GLUTessellatorSupport's internal GLU tessellator for use. This initializes the internal GLUtessellator to a new instance by invoking GLU.gluNewTess(), and configures the tessellator with the specified callback and normal with calls to GLU.gluTessCallback(javax.media.opengl.glu.GLUtessellator, int, javax.media.opengl.glu.GLUtessellatorCallback) and GLU.gluTessNormal(javax.media.opengl.glu.GLUtessellator, double, double, double), respectively.

Parameters:

callback - the callback to configure the GLU tessellator with.

normal - the normal to configure the GLU tessellator with.

Throws:

IllegalArgumentException - if the callback or the normal is null.

convertGLUTessErrorToString

public static String convertGLUTessErrorToString(int errno)

Converts the specified GLU tessellator error number to a string description. This returns "unknown" if the error number is not recognized.

Parameters:

errno - a GLU enumeration indicating the error.

Returns:

a string description of the error number.

createOGLDrawPrimitivesCallback

public static GLUtessellatorCallback createOGLDrawPrimitivesCallback(GL2 gl)

Creates a new GLUtessellatorCallback that draws tessellated polygons as OpenGL primitives by calling glBegin, glEnd, and glVertex.

Parameters:

gl - the GL context to draw into.

Returns:

a new GLUtessellatorCallback for drawing tessellated polygons as OpenGL primtives.

Throws:

IllegalArgumentException - if the GL is null.

endTessellation

public void endTessellation()

Frees any GLU resources used by this GLUTessellatorSupport, and invalidates this instance's internal GLU tessellator.

getGLUtessellator

public GLUtessellator getGLUtessellator()

Returns this GLUTessellatorSupport's internal GLUtessellator instance. This returns a valid GLUtessellator instance if called between beginTessellation(javax.media.opengl.glu.GLUtessellatorCallback, gov.nasa.worldwind.geom.Vec4) and endTessellation(). This returns null if called from outside a beginTessellation/endTessellation block.

Returns:

the internal GLUtessellator instance, or null if called from outside a beginTessellation/endTessellation block.