com.shc.webgl4j.client

Class WebGLContext.Attributes

java.lang.Object

com.google.gwt.core.client.JavaScriptObject

com.shc.webgl4j.client.WebGLContext.Attributes

Enclosing class:

WebGLContext

public static class WebGLContext.Attributes
extends com.google.gwt.core.client.JavaScriptObject

This class represents the context attributes that were used to create a context, or the attributes that will be used to create a context. The attributes are nothing but the properties of the context. Note that there will be no effect to the context even if you change the attributes once the context is created. To be sure that the requested attributes are accepted by the implementation, compare the attributes of the created context.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Attributes()

Method Summary

Modifier and Type	Method and Description
static WebGLContext.Attributes	create() Creates an Attributes object with the default values as specified in the WebGL 1.0 Specification.
boolean	getAlpha() Returns whether the draw buffer has an alpha channel.
boolean	getAntialias() Returns whether anti aliasing is enabled.
boolean	getDepth() Returns the depth property of the WebGLContext.
boolean	getFailIfMajorPerformanceCaveat() If the value is true, context creation will fail if the implementation determines that the performance of the created WebGL context would be dramatically lower than that of a native application making equivalent OpenGL calls.
boolean	getPremultipliedAlpha() If the value is true the page compositor will assume the drawing buffer contains colors with premultiplied alpha.
boolean	getPreserveDrawingBuffer() If false, once the drawing buffer is presented as described in the Drawing Buffer section, the contents of the drawing buffer are cleared to their default values.
boolean	getStencil() Returns whether there is a stencil buffer associated with the context.
void	setAlpha(boolean alpha) Sets the existence of the alpha channel on the drawing buffer.
void	setAntialias(boolean antialias) Sets the antialias property of the to be created context.
void	setDepth(boolean depth) Sets the depth property of the WebGLContext.
void	setFailIfMajorPerformanceCaveat(boolean fail) If the value is true, context creation will fail if the implementation determines that the performance of the created WebGL context would be dramatically lower than that of a native application making equivalent OpenGL calls.
void	setPremultipliedAlpha(boolean premultipliedAlpha) If the value is true the page compositor will assume the drawing buffer contains colors with premultiplied alpha.
void	setPreserveDrawingBuffer(boolean preserveDrawingBuffer) If false, once the drawing buffer is presented as described in the Drawing Buffer section, the contents of the drawing buffer are cleared to their default values.
void	setStencil(boolean stencil) Sets whether there is a stencil buffer associated with the context.

Methods inherited from class com.google.gwt.core.client.JavaScriptObject

cast, createArray, createArray, createFunction, createObject, equals, hashCode, toSource, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Attributes

protected Attributes()

Method Detail

create

public static WebGLContext.Attributes create()

Creates an Attributes object with the default values as specified in the WebGL 1.0 Specification. The default values for the properties are as follows.

     alpha: true
     depth: true
     stencil: false
     antiAlias: true
     preMultipliedAlpha: true
     preserveDrawingBuffer: false
     failIfMajorPerformanceCaveat: false
 

Returns:

An attributes object that contain the default values.

getAlpha

public final boolean getAlpha()

Returns whether the draw buffer has an alpha channel. An alpha channel is required for OpenGL to performing the destination alpha operations and composition with the page. The default value for this is true.

Returns:

Whether the draw buffer has an Alpha-channel.

setAlpha

public final void setAlpha(boolean alpha)

Sets the existence of the alpha channel on the drawing buffer. If the value is true, the drawing buffer has an alpha channel for the purposes of performing OpenGL destination alpha operations and compositing with the page. If the value is false, no alpha buffer is available. The default value for this is true.

Parameters:

alpha - The value of the alpha channel.

getAntialias

public final boolean getAntialias()

Returns whether anti aliasing is enabled. This is dependent on the implementation. So there is no guarantee that the implementation respects this property. The default value for this is true.

Returns:

Whether anti aliasing is enabled.

setAntialias

public final void setAntialias(boolean antialias)

Sets the antialias property of the to be created context. If the value is true and the implementation supports antialiasing the drawing buffer will perform antialiasing using its choice of technique (multisample/supersample) and quality. If the value is false or the implementation does not support antialiasing, no antialiasing is performed. The default value for this property is true.

Parameters:

antialias - The new value of the antialiasing property.

getDepth

public final boolean getDepth()

Returns the depth property of the WebGLContext. If the value is true, then the drawing buffer has a depth buffer of at least 8 bits. If the value is false, then no depth buffer is available for that context.

Returns:

The depth property of WebGLContext.

setDepth

public final void setDepth(boolean depth)

Sets the depth property of the WebGLContext. If the new value is true, then the drawing buffer will have a depth buffer that is at least 8 bits. If the value is false, then no depth buffer is available for the context. However, this is just a request, you have to check the property after the context is created.

Parameters:

depth - The depth property of WebGLContext.

getFailIfMajorPerformanceCaveat

public final boolean getFailIfMajorPerformanceCaveat()

If the value is true, context creation will fail if the implementation determines that the performance of the created WebGL context would be dramatically lower than that of a native application making equivalent OpenGL calls. This could happen for a number of reasons, including:

• An implementation might switch to a software rasterizer if the user's GPU driver is known to be unstable.
• An implementation might require reading back the framebuffer from GPU memory to system memory before compositing it with the rest of the page, significantly reducing performance.

Applications that don't require high performance should leave this parameter at its default value of false. Applications that require high performance may set this parameter to true, and if context creation fails then the application may prefer to use a fallback rendering path.

Returns:

Whether the context fails if there is a major performance caveat.

setFailIfMajorPerformanceCaveat

public final void setFailIfMajorPerformanceCaveat(boolean fail)

If the value is true, context creation will fail if the implementation determines that the performance of the created WebGL context would be dramatically lower than that of a native application making equivalent OpenGL calls. This could happen for a number of reasons, including:

• An implementation might switch to a software rasterizer if the user's GPU driver is known to be unstable.
• An implementation might require reading back the framebuffer from GPU memory to system memory before compositing it with the rest of the page, significantly reducing performance.

Applications that don't require high performance should leave this parameter at its default value of false. Applications that require high performance may set this parameter to true, and if context creation fails then the application may prefer to use a fallback rendering path.

Parameters:

fail - Whether the context should fail if there is a major performance caveat.

getPremultipliedAlpha

public final boolean getPremultipliedAlpha()

If the value is true the page compositor will assume the drawing buffer contains colors with premultiplied alpha. If the value is false the page compositor will assume that colors in the drawing buffer are not premultiplied. This flag is ignored if the alpha flag is false. See Premultiplied Alpha for more information on the effects of the premultipliedAlpha flag.

Returns:

Whether the drawing buffer contains colors with premultiplied alpha.

setPremultipliedAlpha

public final void setPremultipliedAlpha(boolean premultipliedAlpha)

If the value is true the page compositor will assume the drawing buffer contains colors with premultiplied alpha. If the value is false the page compositor will assume that colors in the drawing buffer are not premultiplied. This flag is ignored if the alpha flag is false. See Premultiplied Alpha for more information on the effects of the premultipliedAlpha flag.

Parameters:

premultipliedAlpha - Whether the drawing buffer should accept colors with premultiplied alpha.

getPreserveDrawingBuffer

public final boolean getPreserveDrawingBuffer()

If false, once the drawing buffer is presented as described in the Drawing Buffer section, the contents of the drawing buffer are cleared to their default values. All elements of the drawing buffer (color, depth and stencil) are cleared. If the value is true the buffers will not be cleared and will preserve their values until cleared or overwritten by the author.

On some hardware setting the preserveDrawingBuffer flag to true can have significant performance implications.

Returns:

Whether the drawing buffer is preserved after presenting.

setPreserveDrawingBuffer

public final void setPreserveDrawingBuffer(boolean preserveDrawingBuffer)

If false, once the drawing buffer is presented as described in the Drawing Buffer section, the contents of the drawing buffer are cleared to their default values. All elements of the drawing buffer (color, depth and stencil) are cleared. If the value is true the buffers will not be cleared and will preserve their values until cleared or overwritten by the author.

On some hardware setting the preserveDrawingBuffer flag to true can have significant performance implications.

Parameters:

preserveDrawingBuffer - Whether the drawing buffer should be preserved after presenting.

getStencil

public final boolean getStencil()

Returns whether there is a stencil buffer associated with the context. If the value is true, the drawing buffer has a stencil buffer of at least 8 bits. If the value is false, no stencil buffer is available.

Returns:

Whether there is a stencil buffer of at least 8 bits.

setStencil

public final void setStencil(boolean stencil)

Sets whether there is a stencil buffer associated with the context. If the value is true, the drawing buffer has a stencil buffer of at least 8 bits. If the value is false, no stencil buffer is available.

Parameters:

stencil - Whether a stencil buffer of at least 8 bits should be used.