RGBA32F texture format not supported on Chrome 46

[hcomere]

Hello,

The following call to glTexImage2D returns GL_INVALID_ENUM on Chrome 46 but works on Firefox 42.

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA32F, GL_FLOAT, data);

The following link returns that Chrome supports OES_texture_float extension : https://www.khronos.org/registry/webgl/sdk/tests/conformance/extensions/oes-texture-float.html?webglVersion=1

Any hint ?

Regards, Harold

[kripken]

Perhaps chrome on your machine fails to use that extension (blacklisting maybe)? Might be useful to find some online demo of that feature and see if it works for you.

[hcomere]

Hello,

Sadly, i tested my code on 7 machines with different hardware and this happened 7 times.

A webgl demo using float32 textures is working but the correspondant webgl call is :

gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.FLOAT, data);

Note the internal format gl.RGBA without precision. Where can i see how emscripten translate opengl es glTexImage2D calls to webgl texImage2D calls ?

Thanks,

Regards, Harold

[kripken]

In a debug or profiling build you can just look in the emitted code for function _glTextImage2D. Or look in src/library_gl.js

[juj]

In GLES2 code, the texture format enum GL_RGBA32F is incorrect and not supported. This comes from GLES2 not having the sized internal formats, but these came in later. The correct form as you pointed out in a later comment is to use the unsized internal format GL_RGBA. This would be the same in native GLES2 code (native implementations that do support GL_RGBA32F either have some other extension that enables it, or do so unofficially).

Therefore the call you want to make is

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_FLOAT, data);

GLES3 brings support to sized internal formats, so GL_RGBA32F should work if you create a GLES3/WebGL2 context.

Does this match what you are seeing? If so, sounds like we can close this issue?

[hcomere]

Hello,

I understand that sized internal formats are supported only since GLES3/WebGL2. But it remains some questions about compiling GLES2 code with emscripten :

1) Why does texImage2d with sized internal format work on FireFox ? I have saw that FireFox allows an experimental WebGL2 context, does emscripten create it if available or does emscripten follows the simple pattern "OpenGLES2 => WebGL1, OpenGLES3 => WebGL2" ?

2) Why does RGBA16F internal format works with Chrome where the RGBA32F does not ? Is there an existing chrome WebGL1 extension allowing it ?

I feel that it is mostly a question of extensions.

Regards, Harold

[juj]

1) I can't remember why GL_RGBA32F works on Firefox in WebGL1. It could be the case that this "leaks" through by accident, or that there is some extension I can't recall right now. It is best to avoid using it though, unless you can find a piece of spec wording that lets you.

2) RGBA16F sized internal format is exposed by this extension: https://www.khronos.org/registry/webgl/extensions/EXT_color_buffer_half_float/ , and both FF and Chrome should support it when that extension is activated.

2015-12-18 13:27 GMT+02:00 Harold Comere notifications@github.com:

Hello,

I understand that sized internal formats are supported only since GLES3/WebGL2. But it remains some questions about compiling GLES2 code with emscripten :

1) Why does texImage2d with sized internal format work on FireFox ? I have saw that FireFox allows an experimental WebGL2 context, does emscripten create it if available or does emscripten follows the simple pattern "OpenGLES2 => WebGL1, OpenGLES3 => WebGL2" ?

2) Why does RGBA16F internal format works with Chrome where the RGBA32F does not ? Is there an existing chrome WebGL1 extension allowing it ?

I feel that it is mostly a question of extensions.

Regards, Harold

— Reply to this email directly or view it on GitHub https://github.com/kripken/emscripten/issues/3946#issuecomment-165752691 .

[hcomere]

Hi,

Sorry for the response delay but i was not able to work more on this issue until now.

With WebGL1 it is mandatory to have format == internal format, without size. So, as it was pointed out, right call for :

• RGBA32F textures is

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_FLOAT, data);

• RGBA16F texture is

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_HALF_FLOAT, data);

And this works as expected on both Chrome and FireFox :)

Therefore the renderer is responsible to convert format / internal format couple according to target platform.

Finally, that is not an emscripten issue.

Thanks for your help !

Regards, Harold