The complete list of promoted extensions in WebGL2

I got a chance to update our renderer we use to WebGL2. To make the renderer as backward compatible as possible we keep tracking of loaded extensions( as we did before the upgrade ) and emulate extensions even if such extension was promoted. The renderer does a few relevant things with extensions. From outside, everything is quite transparent.

To make it work smoothly, I need the complete list of promoted extensions. Have found few blogs, but those lists are not complete. Other lists which I have found on GitHub look wrong because they have redundant extensions which were in fact not promoted or were dropped. I have not found much in the docs.

So, I did some empirical research and found :

// 12 extensions were promoted in WebGL2 without surprises
[
  'ANGLE_instanced_arrays',
  'EXT_blend_minmax',
  'EXT_frag_depth',
  'EXT_shader_texture_lod',
  'EXT_sRGB',
  'OES_element_index_uint',
  'OES_standard_derivatives',
  'OES_texture_float',
  'OES_texture_half_float',
  'OES_vertex_array_object',
  'WEBGL_depth_texture',
  'WEBGL_draw_buffers',
]

Particularly I'm concerned about OES_texture_float_linear and OES_texture_half_float_linear extensions which are not in my list. Implementation of WebGL2 I have locally has OES_texture_float_linear but does not have OES_texture_half_float_linear, while WebGL had both of them. I'm aware that in the WebGL1 context OES_texture_float_linear acts a bit differently, so my intuition says there could be problems.

Also, something weird happened with the disjoint_timer_query extension. That extension was merged in partially. WebGL2 contexts got some properties of that extension. I have disjoint_timer_query_webgl2 in Chrome which has all the properties except one getQueryObject which was renamed to getQueryParameter, but in Firefox the disjoint_timer_query extension is still available with a WebGL2 context.

So, is that list complete? And, particularly, should OES_texture_half_float_linear be on the list? And why is it gone, while the analogous OES_texture_float_linear stayed?

Appreciate your help.

So final answer ( probably ) should be :

// 14 extensions were promoted in WebGL2
[
  'ANGLE_instanced_arrays',
  'EXT_blend_minmax',
  'EXT_frag_depth',
  'EXT_shader_texture_lod',
  'OES_element_index_uint',
  'OES_standard_derivatives',
  'OES_texture_float',
  'OES_texture_half_float',
  'OES_vertex_array_object',
  'WEBGL_depth_texture',
  'WEBGL_draw_buffers',
  /* with caveats */
  'EXT_sRGB',
  'OES_texture_half_float_linear',
  'EXT_disjoint_timer_query',
]

Please note that last three extensions were promoted with caveats. Extension EXT_sRGB lost a constant SRGB_ALPHA. Extension OES_texture_half_float_linear was promoted while analogous OES_texture_float_linear was not. Extension EXT_disjoint_timer_query promoted partially. Some properties of that extension appeared in WebGL2 context, while other properties were moved to EXT_disjoint_timer_query_webgl2 extension. Also, currently ( 2017.05.16 ) Firefox WebGL2 context still has EXT_disjoint_timer_query extensions and no EXT_disjoint_timer_query_webgl2 extension.

WebGL2 requires support for half and floating point textures. It also requires filtering for half textures but it does not require support for filtered floating point textures.

That's why OES_texture_half_float_linear missing and OES_texture_float_linear is optional. Most mobile devices do not support filtering for floating point textures.

In other words you should add OES_texture_half_float_linear to your list of promoted extensions.

Another extension that has a strange history is EXT_color_buffer_float. WebGL1 shipped without it. It was assumed to render to a floating point texture all you needed was first OES_texture_float and then make a floating point texture, attach it to a framebuffer and check gl.checkFramebufferStatus. But, a year or so after WebGL shipped someone pointed out that was not enough and so EXT_color_buffer_float was added but it was not enforced because doing so would have broke pages.

In WebGL2 it is enforced. You can not render to a floating point texture without enabling EXT_color_buffer_float. Same for EXT_color_buffer_half_float.