third_party/webgl/extensions/WEBGL_compress_texture/index.html - Issue 9360034: Remove everthing except conformance tests in the deps/third_party/webgl

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Issue 9360034: Remove everthing except conformance tests in the deps/third_party/webgl (Closed) Base URL: svn://chrome-svn/chrome/trunk/deps/

Patch Set: Created 8 years, 10 months ago

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Index: third_party/webgl/extensions/WEBGL_compress_texture/index.html

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--- third_party/webgl/extensions/WEBGL_compress_texture/index.html (revision 121077)

+++ third_party/webgl/extensions/WEBGL_compress_texture/index.html (working copy)

@@ -1,186 +0,0 @@

-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"

- "http://www.w3.org/TR/html4/strict.dtd">

-<html lang="en">

-<head>

- <meta http-equiv="content-type" content="text/html; charset=utf-8">

- <title>WebGL WEBGL_compress_texture Extension Draft Specification</title>

- <link rel="stylesheet" type="text/css" href="../../resources/webgl-extension.css" />

- <link rel="stylesheet" type="text/css" href="../../resources/default.css" />

- <script src="../../resources/jquery-1.3.2.min.js" type="text/javascript"></script>

-</head>

-

- <div>

- <a href="http://webgl.org/"><img alt=WebGL height=72 src="../../resources/WebGL-Logo.png" width=156></a>

- <div class=right>

- <a href="http://khronos.org/"><img alt=Khronos height=60 src="../../resources/KhronosGroup-3D.png" width=220></a>

- </div>

-

- <h1>WebGL WEBGL_compress_texture Extension Draft Specification</h1>

- <h2 class="no-toc">Name</h2>

- <p> WEBGL_compress_texture </p>

- <h2 class="no-toc">Contact</h2>

- <p> <a href="https://www.khronos.org/webgl/public-mailing-list/">WebGL working group</a> (public_webgl 'at' khronos.org) </p>

- <h2 class="no-toc">Contributors</h2>

- <p> Members of the WebGL working group </p>

- <h2 class="no-toc">Version</h2>

- <p> Last modified date: April 5, 2011

- </p>

- <h2 class="no-toc">Number</h2>

- <p> WebGL extension #6 </p>

- <h2 class="no-toc">Dependencies</h2>

- <p> Written against the WebGL API 1.0 specification. </p>

- <h2 class="no-toc">Overview</h2>

- <p>

- This extension exposes compressed texture functionality to WebGL.

- </p>

- <p>

- In WebGL we can not expose compressed texture formats directly to authors because web content

- is supposed to work everywhere. This proposal leaves the compression formats up to the WebGL

- implementation in an opaque way. The user provides hints to the implemenation on what kind of compression

- is appropriate and it is up to the WebGL implemenation to decide on a compression format

- or possibly no compression at all.

- </p>

- <p>

- Because compression can be a slow the process of compression is handled asynchronously. The

- user provides that data as an image, video, canvas or ArrayBufferView. The implementation then

- compressed the image and returns a WebGLCompressedTexture object. That object can then be

- passed to the standard compressedTexImage2D function although with unneeded argements removed.

- </p>

- <h2 class="no-toc">IDL</h2>

- <p>

-<pre class="idl">

-module webgl {

-interface WebGLCompressedTexture : WebGLObject {

- readonly attribute long size;

- readonly attribute GLenum error;

-};

-interface WEBGL_compress_texture {

- const GLenum PRESERVE_ALPHA = 0x0001;

- const GLenum PRESERVE_TRANSPARENCY = 0x0002;

- const GLenum PRESERVE_RGB = 0x0004;

- compressTexture(GLenum usage, GLsizei width, GLsizei height, GLenum format, GLenum type,

- ArrayBufferView pixels, Function callback);

- compressTexture(GLenum usage, ImageData pixels, Function callback);

- compressTexture(GLenum usage, HTMLImageElement image, Function callback);

- compressTexture(GLenum usage, HTMLCanvasElement canvas, Function callback);

- compressTexture(GLenum usage, HTMLVideoElement video, Function callback);

- compressedTexImage2D(GLenum target, GLint level, GLint border, WebGLCompressedTexture pixels);

-};

-</pre>

- <h2 class="no-toc">Description</h2>

- <p>

- All forms are asynchronous. When compression is finished the <code>callback</code>

- is called and passed a <code>WebGLCompressedTexture</code>

- object which can then be used with <code>compressedTexImage2D</code>.

- </p>

- <p>

- <code>compressTexture</code> takes 5 forms. The first form takes an <code>ArrayBufferView</code>.

- The <code>width</code>, <code>height</code>, <code>format</code>, and <code>type</code>

- arguments have the same meaning as they do in <code>texImage2D</code>. They describe the format

- of the pixels in the <code>ArrayBufferView</code>.

- </p>

- <p>

- The other 4 forms of <code>compressTexture</code> take an <code>ImageData</code>,

- <code>HTMLImageElement</code>, <code>HTMLCanvasElement</code>, or an <code>HTMLVideoElement</code>

- repsectively. As such they derive width, height, type and format from the element.

- </p>

- <p>

- <code>usage</code> is a kind of hint to the implementation to help it choose a

- compression format. <code>usage</code> is some logical OR of the following bits

- </p>

- <dl>

- <dt><code>PRESERVE_ALPHA</code></dt>

- <dd>The compression format chosen must support alpha more than 1 bit of alpha.

- </dd>

- <dt><code>PRESERVE_TRANSPARENCY</code></dt>

- <dd>The compression format chosen must have at least 1 bit of alpha

- </dd>

- <dt><code>PRESERVE_RGB</code></dt>

- <dd>The compression format chosen must not be lossy to a specific

- color. In other words, it can not weight R less than G because

- the intended use of the texture is not for color.

- </dd>

- </dl>

- <p>

- The implementation must choose a compression format that respects the <code>usage</code> argument.

- If no such compression format is available the implementation must choose an uncompressed format.

- </p>

- <p class="issue">

- Should the spec define what is acceptable compression? For example PRESERVE_TRANSPARENCY basically means use DXT1 where as

- PRESERVE_ALPHA means use DXT5 on systems that support those formats. On systems with no compression

- using 5_6_5 or 5_5_5_1 is also fine assuming PRESERVE_ALPHA is not requested.

- Is 5_6_5 okay for PRESERVE_RGB? Is 4_4_4_4 ok for PRESERVE_ALPHA?

- </p>

- <p>The <code>callback</code> is always called and passed a <code>WebGLCompressedTexture</code> object. If there was an error

- the <code>error</code> attribute will be set to standard GL error value. Otherwise it is set to <code>NO_ERROR</code>.

- </p>

- <p><code>size</code> is the number of bytes used by the compressed texture. It will be 0

- if there was an error.

- </p>

- <p>Passing a <code>WebGLCompressedTexture</code> who's <code>error</code> attribute is not <code>NO_ERROR</code> to <code>compressTexImage2D</code> generates

- <code>INVALID_OPERATION</code>.</p>

- <h2 class="no-toc">Errors</h2>

- <p>

- Errors are returned on the WebGLCompressedTexture object's <code>error</code> attribute.

- </p>

- <p>

- <code>error</code> is set to <code>INVALID_VALUE</code> if

- <code>width</code> or <code>height</code> would generate an <code>INVALID_VALUE</code> when calling

- texImage2D.

- </p>

- <p>

- <code>error</code> is set to <code>INVALID_ENUM</code> if type or format is not one of the types

- or formats excepted by texImage2D.

- </p>

- <p>

- <code>error</code> is set to <code>INVALID_OPERATION</code> if the size of the <code>ArrayBufferView</code> is

- not greater than or equal to the size of the data described by width, height, format and type.

- </p>

- <h2 class="no-toc">Notes</h2>

- <p>

- compressedTexSubImage2D is not implemented.

- </p>

- <p>

- <code>texSubImage2D</code> and <code>copyTexSubImage2D</code> must both fail on textures created with <code>compressedTexImage2D</code>.

- For consistency this is true even if the implementation did not actually compress the texture.

- </p>

- <p>

- Rendering to a framebuffer object with an attached texture created by <code>compressedTexImage2D</code> must fail

- with <code>INVALID_FRAMEBUFFER_OPERATION</code> even if the implemenation did not actually compress the texture.

- </p>

- <p>

- <code>compressTexture</code> must succeed for all valid dimensions defined by <code>gl.getParameter(gl.MAX_TEXTURE_SIZE).</code>

- That means for example a 7x5 texture passed to compressTexture on a system who's texture compression

- format requires textures that are a multiple of 4 or 8 in each dimension would choose not to compress

- a 7x5 texture but instead provide it uncompressed or in some other format that can handle a 7x5 texture.

- </p>

- <p>

- If both <code>PRESERVE_ALPHA</code> and <code>PRESERVE_TRANSPARENCY</code> are specified

- <code>PRESERVE_ALPHA</code> takes precedence. In other words the implemention must choose

- a compression format with more than 1 bit of alpha.

- </p>

- <h2 class="no-toc">Unresolved issues</h2>

- <h2 class="no-toc">Revision History</h2>

- <p>

- <ul>

- <li> 2011/04/04 Initial draft.</li>

- <li> 2011/04/05 Fixed typos. Changed error mechanism. Added size.</li>

- </ul>

- </p>

-</body>

-</html>