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The surfaceless context extension can be used to bind a context without a surface. We can use this to avoid creating a dummy surface when the CoglContext is first created. Otherwise we have to have the dummy surface so that we can bind it before the first onscreen is created. The main awkward part of this patch is that theoretically according to the GL and GLES spec if you first bind a context without a surface then the default state for glDrawBuffers is GL_NONE instead of GL_BACK. In practice Mesa doesn't seem to do this but we need to be robust against a GL implementation that does. Therefore we track when the CoglContext is first used with a CoglOnscreen and force the glDrawBuffers state to be GL_BACK. There is a further awkward part in that GLES2 doesn't actually have a glDrawBuffers state but GLES3 does. GLES3 also defaults to GL_NONE in this case so if GLES3 is available then we have to be sure to set the state to GL_BACK. As far as I can tell that actually makes GLES3 incompatible with GLES2 because in theory if the application is not aware of GLES3 then it should be able to assume the draw buffer is always GL_BACK. Reviewed-by: Robert Bragg <robert.bragg@intel.com> (cherry picked from commit e5f28f1e75db9bdc4f2688f420a74f908f96cf76) Conflicts: cogl/winsys/cogl-winsys-egl-kms.c cogl/winsys/cogl-winsys-egl-x11.c |
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| .. | ||
| cogl-all-functions.h | ||
| cogl-core-functions.h | ||
| cogl-fixed-functions.h | ||
| cogl-gles1-functions.h | ||
| cogl-gles2-functions.h | ||
| cogl-glsl-functions.h | ||
| cogl-in-gles1-core-functions.h | ||
| cogl-in-gles2-core-functions.h | ||
| cogl-in-gles-core-functions.h | ||