From a959c53b7ac91e489bf0959391e892790b9ff248 Mon Sep 17 00:00:00 2001 From: Kenneth Russel Date: Mon, 15 Jun 2009 22:57:38 +0000 Subject: Copied JOGL_2_SANDBOX r1957 on to trunk; JOGL_2_SANDBOX branch is now closed git-svn-id: file:///usr/local/projects/SUN/JOGL/git-svn/svn-server-sync/jogl/trunk@1959 232f8b59-042b-4e1e-8c03-345bb8c30851 --- make/doc/jogl/spec-overview.html | 509 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 509 insertions(+) create mode 100644 make/doc/jogl/spec-overview.html (limited to 'make/doc/jogl/spec-overview.html') diff --git a/make/doc/jogl/spec-overview.html b/make/doc/jogl/spec-overview.html new file mode 100644 index 000000000..11074e601 --- /dev/null +++ b/make/doc/jogl/spec-overview.html @@ -0,0 +1,509 @@ + + + + JSR 231 Draft Public Review Specification + + + +

JSR 231 Specification Overview

+ +

Preface

+ This specification, an optional set of packages, describes the Java(TM) +bindings to the native OpenGL(R) 3D graphics library profiles: +
+ A binding to the native OpenCL(R) library is not yet specified, but intended to be + included in a maintenance update. +
+ +

Dependencies

+ This binding has dependencies to the following:

+ +
+ +

Package Structure

+ The packages defined by this specification include:
+ + +
+ +

API Binding Conventions

+ The Java language bindings to the pre-existing C APIs in these packages +have been created using a consistent set of rules. Vendor-defined extensions +should make use of the same rules in order to provide a consistent developer +experience.
+
+ The rules for creating the Java language binding are described in the following +sections. These rules should be followed as closely as possible for all future +APIs that share the javax.media.opengl namespace.
+ +

Function Naming

+ Functions are named in the same way as in the C binding. That is, an OpenGL +API function glClear is bound to Java method GL.glClear. Although it would +be possible to drop the gl prefix (since it is redundant with the interface +name GL), the resulting code was deemed to look too foreign to experienced +OpenGL developers. For the same reason, we have also carried over all type +suffixes like 3f and 3fv from methods such as glColor3f and glColor3fv, respectively.
+
+ Extension suffixes, such as EXT, ARB, and vendor-specific suffixes, are +retained so as to match C conventions.
+ +

Mapping of Constants

+ Constants are named in the same way as in the C binding. For instance, +the OpenGL constant GL_RGB is bound to Java constant GL.GL_RGB.
+ +

Mapping of Primitive Types

+ All 8-bit integral types become byte, all 16-bit integral types become +short, and all 32-bit integral types become int. All 32-bit floating-point +types become float and all 64-bit floating-point types become double.
+
+ Integer return values that can only be GL_TRUE or GL_FALSE are mapped to +boolean.
+ +

Mapping of Pointer Arguments

+ OpenGL functions that take pointer arguments fall into several categories:
+ + + Functions that take an untyped (void*) pointer argument for immediate use +are given a single binding that takes a New I/O (NIO) Buffer object. The Buffer +may be of any type allowable by the function (and compatible with the other +arguments to the function) and may be direct or indirect. An example of +an OpenGL API in this category is glTexImage2D.
+
+ Functions that take a typed pointer (e.g., GLfloat *) argument for immediate +use are given two bindings. The first takes a Java primitive array with a +type that matches the C pointer type (i.e., GLfloat* maps to float[]). The +second takes a typed Buffer object (i.e., GLfloat* maps to FloatBuffer). +An example of an OpenGL API in this category is glColor3fv.
+
+ Functions that take an untyped (void*) pointer argument for deferred use +are given a single binding that takes a Buffer object. The Buffer may be of +any type allowable by the function (and compatible with the other arguments +to the function), but must be direct. That is, it may not have been created +from a Java primitive array using the wrap method. The functions that fall +into this category generally have names ending with the suffix "pointer." +An example of an OpenGL API in this category is glVertexPointer. Because these +functions do not consume the data located at the given pointer immediately, +but only at some unspecified later time, it is not possible to use a Java +primitive array whose memory location may change.
+
+ Functions that take a typed (e.g., GLfloat*) pointer argument for deferred +use are given a single binding that takes a typed Buffer object (i.e., GLfloat* +maps to FloatBuffer). The Buffer must be direct. That is, it may not have +been created from a Java primitive array using the wrap method. An example +of an OpenGL API in this category is glFeedbackBuffer.
+
+ Methods that read or write a specific number of values from an array or +Buffer argument do not read or write any subsequent elements of the array +or Buffer.
+
+ An outgoing C char* pointer, if representing a null-terminated, read-only +C string, maps to a Java String. An outgoing C char** pointer, if similarly +representing an array of read-only C strings, maps to a Java String[] (array +of String objects). All other char* pointers, including those representing +mutable C strings as used in some Get methods, are mapped to byte[] and ByteBuffer. +
+ +

Index Parameter for Arrays

+ Each C method argument that is mapped to a primitive array in Java is actually +mapped to two separate parameters: the appropriate primitive array type in +Java and an integer offset parameter. The value of the integer offset is +the index which the method will start reading from within the array. Earlier +indices will be ignored. This mapping provides more congruity with existing +Java APIs and allows reuse of a single array across multiple Java method calls +by changing the index in much the same way that C pointers permit for C arrays.
+ +

Reduction of Method Explosions

+ Since there are two ways to expand a given C method pointer parameter, +it would be possible for C methods with multiple pointer arguments to expand +to many Java methods if one was to consider every possible combination of +mappings (the C method would expand to the number of pointer parameters to +the power of 2). In order to avoid an API explosion, we restrict a given +Java method to like kind mappings only. In other words, a given C method +with N typed pointer parameters for immediate use, where N >= 1, will map +to exactly two Java methods: One with all primitive arrays and one with all +Buffer types.
+
+ Also, methods that accept multiple Buffer arguments require all direct +or all non-direct Buffers. Direct and non-direct buffers should never be +mixed within an API call by an application.
+ +

Byte ordering of Buffers

+ When allocating a New I/O Buffer (in particular, a direct ByteBuffer) to +be passed to the APIs in these packages, it is essential to set the byte +ordering of the newly-allocated ByteBuffer to the native byte +ordering of the platform: e.g. ByteBuffer.allocateDirect(...).order(ByteOrder.nativeOrder());. +The byte order of the ByteBuffer indicates how multi-byte values such as +int and float are stored in the Buffer either using methods like putInt and +putFloat or views such as IntBuffer or FloatBuffer. The Java bindings perform +no conversion or byte swapping on the outgoing data to OpenGL, and the native +OpenGL implementation expects data in the host CPU's byte order, so it is +essential to always match the byte order of the underlying platform when +filling Buffers with data.
+ +

Auto-slicing of Buffers

+ When a Buffer object is passed to an OpenGL function binding, the actual +pointer argument that is passed down to the OpenGL C implementation is equal +to the starting pointer of the Buffer data, plus an offset given by the Buffer.position() +function, multiplied by the data type size in bytes (1 for a ByteBuffer, 2 +for a ShortBuffer, 4 for a IntBuffer or FloatBuffer, and 8 for DoubleBuffer). + The array offset given by Buffer<type>.arrayOffset() is also added +in the offset for wrapped arrays.
+
+ This feature is known as "auto-slicing," as it mimics the effect of calling +slice() on the Buffer object without the overhead of explicit object creation.
+ +

Errors and Exceptions

+ For performance reasons, OpenGL functions do not return error values directly. +Instead, applications must query for errors using functions such as glGetError. +This behavior is largely preserved in the Java language bindings, as described +below.
+
+ In the interest of efficiency, the Java API does not generally throw exceptions. + However, running an application with the DebugGL composable pipeline, which +is part of the API, will force an exception to be thrown at the point of failure.
+
+ Many errors are defined by OpenGL merely to set the error code, rather +than throwing an exception. For example, passing a bad enumerated parameter +value may result in the error flag being set to GL.GL_INVALID_VALUE. Attempting +to check for such errors in the binding layer would require either replicating +the error-checking logic of the underlying engine, or querying the error state +after every function. This would greatly impact performance by inhibiting +the ability of the hardware to pipeline work.
+ +

Security

+ Exception behavior is defined in cases that could otherwise lead to illegal +memory accesses in the underlying OpenGL engine. Implementations should take +necessary steps to prevent the GL from accessing or overwriting memory except +for properly allocated Buffers and array method arguments.
+
+ An implementation should take care to validate arguments correctly before +invoking native methods that could potentially access memory illegally. In +particular, methods that validate the contents of an array (such as a list +of GL attributes) or a Buffer should take precautions against exploits in +which a separate thread attempts to alter the contents of the argument during +the time interval following validation but preceding passage of the argument +to the underlying native engine.
+ +

Sharing of Server-Side OpenGL Objects between GLContexts

+ +Sharing of server-side OpenGL objects such as textures and display +lists among OpenGL contexts is supported in this specification. +However, the specification does not guarantee that a request to share +objects between two contexts will succeed. Certain OpenGL +implementations restrict sharing in certain ways. Applications should +assume that sharing is a request more than an assertion. +Implementations of this specification should, but are not required to, +provide timely notification of a failure of a request to share objects +between two GLContexts, perhaps in the form of a GLException. The +situation in which sharing is most likely to work on all platforms is +between two GLContexts associated with the same GLDrawable. + +

Criteria Used for Inclusion of APIs into the Java Bindings

+ +

OpenGL API Inclusion Criteria

+ OpenGL functions and OpenGL extensions have been included in the Java bindings +according the following rules:
+ + + +

OpenGL GLU API Inclusion Criteria

+ Bindings for all core GLU APIs have been included with the exception of +the GLU NURBS APIs.  These APIs may be included in a future maintenance +release of the Java bindings.
+ +

OpenGL Extensions

+ +

Creating New Extensions

+ While the Java APIs for OpenGL extensions are unconditionally exposed, the +underlying functions may not be present. A program can query whether a potentially +unavailable function is actually available at runtime by using the method +GL.isFunctionAvailable.
+
+ Bindings for OpenGL extensions not covered in this specification may be +supplied by individual vendors or groups. Such bindings may be considered +for inclusion in a future version of the JSR. In order to avoid fragmentation, +vendors creating extension bindings should expose new extensions using the +method GL.getExtension. This method is intended to provide a mechanism for +vendors who wish to provide access to new OpenGL extensions without changing +the public API of the core package.
+
+ Names for added extension methods and extension-defined constants and Java +bindings for C parameters should follow the guidelines set forth in this specfication.
+ +

Accessing Platform-Specific Extensions

+ Platform-specific extensions such as those that begin with WGL, GLX, CGL, +etc. are not included in the API.  Each implementation can choose to +export all, some, or none of these APIs via the GL.getPlatformGLExtensions +API which returns an Object whose underlying data type is specific to a given +implementation.
+                                                                                                                                    +
+ Therefore, any usage of these APIs is both platform and implementation specific.
+ +

OpenGL Version on Runtime System

+ Even though OpenGL extensions whose functionality was included into core +OpenGL by version 2.0, inclusive, are not included in the bindings, it should +be noted that OpenGL version 2.0 is not an absolute requirement on the runtime +system.  This is because a user could query whether any particular function +is available before calling certain core APIs that might not be present.  +Also, if the core function name is not available in the native OpenGL implementation, +the extension named equivalent is used instead, e.g. GL_ARB_framebuffer_object.  +However, in general, it is reasonable to expect at least OpenGL 2.0 to be +installed on the runtime system and an implementor of the API is free to require +the presence of at least OpenGL 2.0 on the target system.
+                                                                                                                                    +
+ In future revisions of the API, this minimum standard may be raised.
+ +

Runtime Version Information

+Any Java Bindings for OpenGL implementation should include version information +in its jar manifest file.  This information can then easily be accessed +at runtime via the java.lang.Package API.  At least the following information +is included in the Reference Implementation jar file manifest: Specification +Title, Specification Vendor, Specification Version, Implementation Vendor, +and Implementation Version.
+ +

Future Maintenance Updates

+ New core APIs found in future versions of OpenGL, as well as new OpenGL +extensions, are expected to be added to the bindings and included into the +javax.media.opengl namespace via future maintenance updates to the API.
+ +

Related Links

+ + + +
http://www.jcp.org/en/jsr/detail?id=231
+ + + +
+http://www.khronos.org/registry/cl/
+ + + +
+http://www.opengl.org/registry/doc/glspec31.20090324.pdf
+ + + +
+http://www.opengl.org/registry/doc/glspec21.20061201.pdf
+ + + +
+http://www.opengl.org/documentation/specs/version2.0/glspec20.pdf
+ + + +
http://www.opengl.org/registry/
+ +

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+http://www.khronos.org/registry/gles/specs/2.0/es_full_spec_2.0.24.pdf

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+http://www.khronos.org/registry/gles/specs/1.1/es_full_spec_1.1.12.pdf

+    
+
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+

+http://www.khronos.org/registry/gles/

+    
+
+   
+
 http://www.opengl.org/documentation/specs/glu/glu1_3.pdf

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+
 http://www.opengl.org/about/arb/index.html

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Revision History

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