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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.5.0_06) on Wed Dec 13 16:20:00 PST 2006 --><TITLE>Canvas3D (Java 3D 1.5.0)</TITLE><META NAME="keywords" CONTENT="javax.media.j3d.Canvas3D class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="Canvas3D (Java 3D 1.5.0)";}</SCRIPT><NOSCRIPT></NOSCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../javax/media/j3d/BranchGroup.html" title="class in javax.media.j3d"><B>PREV CLASS</B></A> <A HREF="../../../javax/media/j3d/CapabilityNotSetException.html" title="class in javax.media.j3d"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../index.html?javax/media/j3d/Canvas3D.html" target="_top"><B>FRAMES</B></A> <A HREF="Canvas3D.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: <A HREF="#nested_classes_inherited_from_class_java.awt.Canvas">NESTED</A> | <A HREF="#field_summary">FIELD</A> | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: <A HREF="#field_detail">FIELD</A> | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">javax.media.j3d</FONT><BR>Class Canvas3D</H2><PRE>java.lang.Object <IMG SRC="../../../resources/inherit.gif" ALT="extended by ">java.awt.Component <IMG SRC="../../../resources/inherit.gif" ALT="extended by ">java.awt.Canvas <IMG SRC="../../../resources/inherit.gif" ALT="extended by "><B>javax.media.j3d.Canvas3D</B></PRE><DL><DT><B>All Implemented Interfaces:</B> <DD>java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable, javax.accessibility.Accessible</DD></DL><HR><DL><DT><PRE>public class <B>Canvas3D</B><DT>extends java.awt.Canvas</DL></PRE><P>The Canvas3D class provides a drawing canvas for 3D rendering. It is used either for on-screen rendering or off-screen rendering. Canvas3D is an extension of the AWT Canvas class that users may further subclass to implement additional functionality. <p> The Canvas3D object extends the Canvas object to include 3D-related information such as the size of the canvas in pixels, the Canvas3D's location, also in pixels, within a Screen3D object, and whether or not the canvas has stereo enabled. <p> Because all Canvas3D objects contain a reference to a Screen3D object and because Screen3D objects define the size of a pixel in physical units, Java 3D can convert a Canvas3D size in pixels to a physical world size in meters. It can also determine the Canvas3D's position and orientation in the physical world. <p> <b>On-screen Rendering vs. Off-screen Rendering</b> <p> The Canvas3D class is used either for on-screen rendering or off-screen rendering. On-screen Canvas3Ds are added to AWT or Swing Container objects like any other canvas. Java 3D automatically and continuously renders to all on-screen canvases that are attached to an active View object. On-screen Canvas3Ds can be either single or double buffered and they can be either stereo or monoscopic. <p> Off-screen Canvas3Ds must not be added to any Container. Java 3D renders to off-screen canvases in response to the <code>renderOffScreenBuffer</code> method. Off-screen Canvas3Ds are single buffered. However, on many systems, the actual rendering is done to an off-screen hardware buffer or to a 3D library-specific buffer and only copied to the off-screen buffer of the Canvas when the rendering is complete, at "buffer swap" time. Off-screen Canvas3Ds are monoscopic. <p> The setOffScreenBuffer method sets the off-screen buffer for this Canvas3D. The specified image is written into by the Java 3D renderer. The size of the specified ImageComponent determines the size, in pixels, of this Canvas3D - the size inherited from Component is ignored. Note that the size, physical width, and physical height of the associated Screen3D must be set explicitly prior to rendering. Failure to do so will result in an exception. <p> The getOffScreenBuffer method retrieves the off-screen buffer for this Canvas3D. <p> The renderOffScreenBuffer method schedules the rendering of a frame into this Canvas3D's off-screen buffer. The rendering is done from the point of view of the View object to which this Canvas3D has been added. No rendering is performed if this Canvas3D object has not been added to an active View. This method does not wait for the rendering to actually happen. An application that wishes to know when the rendering is complete must either subclass Canvas3D and override the postSwap method, or call waitForOffScreenRendering. <p> The setOfScreenLocation methods set the location of this off-screen Canvas3D. The location is the upper-left corner of the Canvas3D relative to the upper-left corner of the corresponding off-screen Screen3D. The function of these methods is similar to that of Component.setLocation for on-screen Canvas3D objects. The default location is (0,0). <p> <b>Accessing and Modifying an Eye's Image Plate Position</b> <p> A Canvas3D object provides sophisticated applications with access to the eye's position information in head-tracked, room-mounted runtime environments. It also allows applications to manipulate the position of an eye relative to an image plate in non-head-tracked runtime environments. <p> The setLeftManualEyeInImagePlate and setRightManualEyeInImagePlate methods set the position of the manual left and right eyes in image plate coordinates. These values determine eye placement when a head tracker is not in use and the application is directly controlling the eye position in image plate coordinates. In head-tracked mode or when the windowEyepointPolicy is RELATIVE_TO_FIELD_OF_VIEW or RELATIVE_TO_COEXISTENCE, this value is ignored. When the windowEyepointPolicy is RELATIVE_TO_WINDOW, only the Z value is used. <p> The getLeftEyeInImagePlate, getRightEyeInImagePlate, and getCenterEyeInImagePlate methods retrieve the actual position of the left eye, right eye, and center eye in image plate coordinates and copy that value into the object provided. The center eye is the fictional eye half-way between the left and right eye. These three values are a function of the windowEyepointPolicy, the tracking enable flag, and the manual left, right, and center eye positions. <p> <b>Monoscopic View Policy</b> <p> The setMonoscopicViewPolicy and getMonoscopicViewPolicy methods set and retrieve the policy regarding how Java 3D generates monoscopic view. If the policy is set to View.LEFT_EYE_VIEW, the view generated corresponds to the view as seen from the left eye. If set to View.RIGHT_EYE_VIEW, the view generated corresponds to the view as seen from the right eye. If set to View.CYCLOPEAN_EYE_VIEW, the view generated corresponds to the view as seen from the "center eye," the fictional eye half-way between the left and right eye. The default monoscopic view policy is View.CYCLOPEAN_EYE_VIEW. <p> <b>Immediate Mode Rendering</b> <p> Pure immediate-mode rendering provides for those applications and applets that do not want Java 3D to do any automatic rendering of the scene graph. Such applications may not even wish to build a scene graph to represent their graphical data. However, they use Java 3D's attribute objects to set graphics state and Java 3D's geometric objects to render geometry. <p> A pure immediate mode application must create a minimal set of Java 3D objects before rendering. In addition to a Canvas3D object, the application must create a View object, with its associated PhysicalBody and PhysicalEnvironment objects, and the following scene graph elements: a VirtualUniverse object, a high-resolution Locale object, a BranchGroup node object, a TransformGroup node object with associated transform, and a ViewPlatform leaf node object that defines the position and orientation within the virtual universe that generates the view. <p> In immediate mode, all rendering is done completely under user control. It is necessary for the user to clear the 3D canvas, render all geometry, and swap the buffers. Additionally, rendering the right and left eye for stereo viewing becomes the sole responsibility of the application. In pure immediate mode, the user must stop the Java 3D renderer, via the Canvas3D object <code>stopRenderer</code> method, prior to adding the Canvas3D object to an active View object (that is, one that is attached to a live ViewPlatform object). <p> Other Canvas3D methods related to immediate mode rendering are: <p> <ul> <code>getGraphicsContext3D</code> retrieves the immediate-mode 3D graphics context associated with this Canvas3D. It creates a new graphics context if one does not already exist. <p> <code>getGraphics2D</code> retrieves the 2D graphics object associated with this Canvas3D. It creates a new 2D graphics object if one does not already exist. <p> <code>swap</code> synchronizes and swaps buffers on a double-buffered canvas for this Canvas3D object. This method should only be called if the Java 3D renderer has been stopped. In the normal case, the renderer automatically swaps the buffer. </ul> <p> <b>Mixed Mode Rendering</b> <p> Mixing immediate mode and retained or compiled-retained mode requires more structure than pure immediate mode. In mixed mode, the Java 3D renderer is running continuously, rendering the scene graph into the canvas. <p> Canvas3D methods related to mixed mode rendering are: <p> <ul> <code>preRender</code> called by the Java 3D rendering loop after clearing the canvas and before any rendering has been done for this frame. <p> <code>postRender</code> called by the Java 3D rendering loop after completing all rendering to the canvas for this frame and before the buffer swap. <p> <code>postSwap</code> called by the Java 3D rendering loop after completing all rendering to the canvas, and all other canvases associated with this view, for this frame following the buffer swap. <p> <code>renderField</code> called by the Java 3D rendering loop during the execution of the rendering loop. It is called once for each field (i.e., once per frame on a mono system or once each for the right eye and left eye on a two-pass stereo system. ⌨️ 快捷键说明
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