CONFORMANCE_RULES.txt

Rules for Claiming a Conformant WebGL Implementation

====================================================

The WebGL API is a web standard, and many web browser implementers

deliver their browser on multiple operating systems (OSs). WebGL

implementations also typically rely on the presence of an OpenGL or

OpenGL ES implementation on the OS. It can be appreciated that a WebGL

implementation therefore has many dependencies. This document attempts

to clarify to potential implementers the rules the Khronos Group uses

to judge whether a particular WebGL implementation is conformant.

There are two primary reasons to submit conformance results:

  A) A web browser implementer desires to certify their WebGL

     implementation as conformant.

  B) A GPU manufacturer delivering an embedded system including web

     browser with WebGL support desires to certify their WebGL

     implementation as conformant.

Each of these situations carries different constraints, so the

conformance rules are phrased differently for each. Typically, a web

browser implementer aims to certify that the WebGL "layer" is correct.

A GPU vendor typically aims to certify that a given device is

physically capable of passing the tests.

A newly-developed WebGL implementation should not support the "webgl"

HTML Canvas context type by default in a shipping version of the

product until reaching conformance. It is acceptable to give end users

an option to turn on WebGL support in a non-conformant implementation

as long as the documentation for that option clearly indicates that

the implementation is not yet conformant and may have compatibility

issues. It is suggested that the Canvas context type

"experimental-webgl" may be supported by default in such

implementations.

A WebGL implementation might reach conformance, but a subsequent

graphics driver release on a particular OS might introduce a

regression causing failures of one or more of the WebGL conformance

tests. In this situation it is not required to revoke support for the

"webgl" HTML Canvas context type. The WebGL implementer should work

with the GPU vendor to ensure the driver regression is fixed. A

situation like this would, however, prevent the WebGL implementer from

conforming to a subsequent version of the test suite.

(A) Conformance Rules for a Web Browser Implementer

===================================================

1. Conformance on a particular operating system

On a given OS, a WebGL implementation will be considered to conform to

a particular version of the conformance suite if the suite passes with

no test failures on at least two GPUs, each from a different

vendor. If the OS only supports a GPU from one vendor, the two-GPU

requirement is dropped.

2. Conformance across multiple operating systems

A WebGL implementation will be considered to conform to a particular

version of the conformance suite if it passes rule (1) on all of the

OSs on which the WebGL implementation is intended to be supported.

3. Conformance as the web browser is upgraded

WebGL conformance results submitted for an earlier version of the

browser carry forward to later versions of the browser that do not

cause any previously passing test to fail.

4. Conformance as the operating system is upgraded

If a new version is released of one of the OSs on which a WebGL

implementation is intended to run, then WebGL conformance results

submitted for earlier versions of that OS carry forward. Future

conformance results must be submitted against the new version of the

OS. If it is anticipated that the older OS version will be supported

for some time, then future conformance results must be submitted

separately for both the old and new versions of the OS.

(B) Conformance Rules for a GPU Vendor

======================================

A GPU vendor submitting conformance results for a WebGL implementation

typically does so because the device containing the GPU includes a

built-in web browser. In this case the following rules apply:

1. Conformance results must be submitted for each GPU and operating

system combination to be certified. It is not required to submit

results for different devices containing the same GPU and running the

same operating system that do not cause any previously passing test to

fail.

2. Conformance results carry forward for a given GPU as the operating

system and graphics driver are upgraded but do not cause any previously

passing test to fail.

Discussion

==========

A WebGL implementation intended to ship on three OSs may reach

conformance on two of them, but due to graphics driver bugs, may be

unable to reach conformance on the third. In this situation the

implementation is not yet considered to be conformant.

An existing WebGL implementation which conformed to an earlier version

of the test suite is not required to remove support for the "webgl"

HTML Canvas context type while in the process of conforming to a later

version of the test suite. However, the implementer must not advertise

conformance to the later version until it has been reached. It is

acceptable for the implementer to advertise details of their

conformance, for example number or percentage of passing or failing

tests, or names of passing or failing tests.

A GPU vendor might submit conformance results in order to use the

WebGL logo in a marketing campaign. In this situation, results may be

submitted in advance of the product becoming available through sales

channels, per the rules above.

The WebGL API has strict security requirements. Even one failing test

may indicate a serious security issue in the WebGL implementation. For

this reason, no exceptions for failing conformance tests will be

granted.

The Khronos Group determines whether a particular WebGL implementation

is conformant based on the implementer's conformance suite

submissions, on multiple OSs and on multiple GPUs as necessary, using

the rules above. An implementer shall not judge their own

implementation conformant simply by applying the above rules.