[vlc-devel] [PATCH] opengl: api: drain error in case of error

[Romain Vimont]

Le 27 janvier 2021 18:13:45 GMT+01:00, Alexandre Janniaux <ajanni at videolabs.io> a écrit :
>Otherwise, the error might be detected afterwards in an unrelated part
>of the code, leading to potential failure or assertion depending on the
>compilation options.
>
>Indeed, an OpenGL call can lead to multiple errors and glGetError must
>be called in loop, as mentioned by the documentation.
>
>https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glGetError.xhtml
>
>> To allow for distributed implementations, there may be several error
>> flags. If any single error flag has recorded an error, the value of
>> that flag is returned and that flag is reset to GL_NO_ERROR when
>> glGetError is called. If more than one flag has recorded an error,
>> glGetError returns and clears an arbitrary error flag value. Thus,
>> glGetError should always be called in a loop, until it returns
>> GL_NO_ERROR, if all error flags are to be reset.
>---
> modules/video_output/opengl/gl_api.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
>diff --git a/modules/video_output/opengl/gl_api.c
>b/modules/video_output/opengl/gl_api.c
>index 1264dde2a1..d990493832 100644
>--- a/modules/video_output/opengl/gl_api.c
>+++ b/modules/video_output/opengl/gl_api.c
>@@ -163,6 +163,10 @@ vlc_gl_api_Init(struct vlc_gl_api *api, vlc_gl_t
>*gl)
>      */
>     api->supports_multisample = version >= 3 && error == GL_NO_ERROR;
> 
>+    /* Drain the errors before continuing. */
>+    while (error != GL_NO_ERROR)

Calling it once should be sufficient, isn't it?

>+        error = api->vt.GetError();
>+
> #ifdef USE_OPENGL_ES2
>     api->is_gles = true;
>/* OpenGL ES 2 includes support for non-power of 2 textures by
>specification
>-- 
>2.30.0
>
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