[Mesa-users] Possible to emulate GL_EXT_texture_rg + (GL_OES_texture_float|GL_OES_texture_half_float)?

[Brian Paul]

On 01/25/2014 02:32 PM, org.mesa3d.mesa-users at io7m.com wrote:
> Hello.
>
> I'm implementing a renderer that uses variance shadow maps. I've
> implemented the technique on OpenGL >= 3.0 core contexts, and on ES3
> with GL_EXT_color_buffer_float and GL_EXT_color_buffer_half_float.
> However, I'd also like to implement it on ES2, and for that I'd like to
> get access to context that exposes exactly those extensions given in the
> subject (so that I can test that all the various texture
> parameters are correct).
>
> Unfortunately, even though the ES3 context exposes
> GL_EXT_color_buffer_float and GL_EXT_texture_rg, it doesn't expose
> GL_OES_texture_float (which, if I follow the specifications to the
> letter, means that I don't get colour-renderable floating point textures
> on ES2). The ES3 context (when being treated as an ES2 context) seems
> to agree:
>
> Mesa: User error: GL_INVALID_OPERATION in glTexImage2D(format = GL_RED,
> type = GL_FLOAT, internalFormat = GL_RED)
>
> According to:
>
>    https://urldefense.proofpoint.com/v1/url?u=https://www.khronos.org/registry/gles/extensions/EXT/EXT_texture_rg.txt&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=lGQMzzTgII0I7jefp2FHq7WtZ%2BTLs8wadB%2BiIj9xpBY%3D%0A&m=sQWzr7RAlp0awDbCE1rHAxA44bzxERadliMFG1RUFAU%3D%0A&s=81384d1326b3369b2d6ce4032ad052c383efaa3304e9d450a3a7106eb7d1c341
>
> The call is valid iff GL_EXT_texture_rg and GL_OES_texture_float are
> present.
>
> Is it possible to get mesa to emulate these calls? Or will I need to
> patch the source?

Off-hand this sounds like a Mesa bug.  Please file a bug report.  Or 
better yet, dig into the source and find where the error is being 
generated, and why.

-Brian