Java 3D API - Execution and Rendering Model

From 54f1415fa01061f0bcc5126605713b9a391cec46 Mon Sep 17 00:00:00 2001 From: phil Date: Fri, 29 Dec 2017 22:53:47 +1300 Subject: Some excellent doc files added --- doc-files/Rendering.html | 148 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 doc-files/Rendering.html (limited to 'doc-files/Rendering.html') diff --git a/doc-files/Rendering.html b/doc-files/Rendering.html new file mode 100644 index 0000000..7415ce8 --- /dev/null +++ b/doc-files/Rendering.html @@ -0,0 +1,148 @@ + + + + + Java 3D API - Execution and Rendering Model + + +

Execution and Rendering Model

Java 3D's execution and rendering model assumes the +existence of a VirtualUniverse +object and an attached scene graph. This +scene graph can be minimal and not noticeable from an application's +perspective when using immediate-mode rendering, but it must exist. +

Java 3D's execution model intertwines with its rendering modes +and +with +behaviors and their scheduling. This chapter first describes the three +rendering modes, then describes how an application starts up a +Java 3D +environment, and finally it discusses how the various rendering modes +work within this framework. +

Three Major Rendering Modes

Java 3D supports three different modes for rendering scenes: +immediate +mode, retained mode, and compiled-retained mode. These three levels of +API support represent a potentially large variation in graphics +processing speed and in on-the-fly restructuring. +

Immediate Mode

Immediate mode allows maximum flexibility at some cost in rendering +speed. The application programmer can either use or ignore the scene +graph structure inherent in Java 3D's design. The programmer can +choose +to draw geometry directly or to define a scene graph. Immediate mode +can be either used independently or mixed with retained and/or +compiled-retained mode rendering. The immediate-mode API is described +in the "Immediate-Mode Rendering" section.

Retained Mode

Retained mode allows a great deal of the flexibility provided by +immediate mode while also providing a substantial increase in rendering +speed. All objects defined in the scene graph are accessible and +manipulable. The scene graph itself is fully manipulable. The +application programmer can rapidly construct the scene graph, create +and delete nodes, and instantly "see" the effect of edits. Retained +mode also allows maximal access to objects through a general pick +capability. +

Java 3D's retained mode allows a programmer to construct +objects, +insert objects into a database, compose objects, and add behaviors to +objects. +

In retained mode, Java 3D knows that the programmer has defined +objects, knows how the programmer has combined those objects into +compound objects or scene graphs, and knows what behaviors or actions +the programmer has attached to objects in the database. This knowledge +allows Java 3D to perform many optimizations. It can construct +specialized data structures that hold an object's geometry in a manner +that enhances the speed at which the Java 3D system can render it. +It +can compile object behaviors so that they run at maximum speed when +invoked. It can flatten transformation manipulations and state changes +where possible in the scene graph. +

Compiled-Retained Mode

Compiled-retained mode allows the Java 3D API to perform an +arbitrarily +complex series of optimizations including, but not restricted to, +geometry compression, scene graph flattening, geometry grouping, and +state change clustering. +

Compiled-retained mode provides hooks for end-user manipulation and +picking. Pick operations return the closest object (in scene graph +space) associated with the picked geometry. +

Java 3D's compiled-retained mode ensures effective graphics +rendering +speed in yet one more way. A programmer can request that Java 3D +compile an object or a scene graph. Once it is compiled, the programmer +has minimal access to the internal structure of the object or scene +graph. Capability flags provide access to specified components that the +application program may need to modify on a continuing basis. +

A compiled object or scene graph consists of whatever internal +structures Java 3D wishes to create to ensure that objects or +scene +graphs render at maximal rates. Because Java 3D knows that the +majority +of the compiled object's or scene graph's components will not change, +it can perform an extraordinary number of optimizations, including the +fusing of multiple objects into one conceptual object, turning an +object into compressed geometry or even breaking an object up into +like-kind components and reassembling the like-kind components into new +"conceptual objects." +

Instantiating the Render Loop

From an application's perspective, Java 3D's render loop runs +continuously. Whenever an application adds a scene branch to the +virtual world, that scene branch is instantly visible. This high-level +view of the render loop permits concurrent implementations of +Java 3D +as well as serial implementations. The remainder of this section +describes the Java 3D render loop bootstrap process from a +serialized +perspective. Differences that would appear in concurrent +implementations are noted as well. +

An Application-Level +Perspective

First the application must construct its scene graphs. It does this +by +constructing scene graph nodes and component objects and linking them +into self-contained trees with a BranchGroup node as a root. The +application next must obtain a reference to any constituent nodes or +objects within that branch that it may wish to manipulate. It sets the +capabilities of all the objects to match their anticipated use and only +then compiles the branch using the BranchGroup's compile +method. Whether it compiles the branch, the application can add it to +the virtual universe by adding the BranchGroup to a Locale object. The +application repeats this process for each branch it wishes to create. +Note that for concurrent Java 3D implementations, whenever an +application adds a branch to the active virtual universe, that branch +becomes visible. +

Retained and +Compiled-Retained Rendering Modes

This initialization process is identical for retained and +compiled-retained modes. In both modes, the application builds a scene +graph. In compiled-retained mode, the application compiles the scene +graph. Then the application inserts the (possibly compiled) scene graph +into the virtual universe. +

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