- unsigned glx_format = 0;
- _glXQueryDrawable(display, drawable, GLX_TEXTURE_FORMAT_EXT, &glx_format);
- GLenum format;
- switch (glx_format) {
- case GLX_TEXTURE_FORMAT_RGB_EXT:
- format = GL_RGB;
- break;
- case GLX_TEXTURE_FORMAT_RGBA_EXT:
- format = GL_RGBA;
- break;
- case GLX_TEXTURE_FORMAT_NONE_EXT:
- // XXX: This really shouldn't happen but some
- // implementations (Mesa) appear return bogus results to
- // the GLX_TEXTURE_FORMAT_EXT query
- default:
- //os::log("apitrace: warning: %s: unexpected GLX_TEXTURE_FORMAT_EXT 0x%u\n", __FUNCTION__, glx_format);
- format = GL_RGBA;
- break;
- }
+ // XXX: We always use GL_RGBA format to read the pixels because:
+ // - some implementations (Mesa) seem to return bogus results
+ // for GLX_TEXTURE_FORMAT_EXT
+ // - hardware usually stores GL_RGB with 32bpp, so it should be
+ // faster to read/write
+ // - it is more robust against GL_(UN)PACK_ALIGNMENT state
+ // changes
+ // The drawback is that traces will be slightly bigger.
+ GLenum format = GL_RGBA;