8f3380adc3
4 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Robert Bragg
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df21e20f65 |
Adds CoglError api
Although we use GLib internally in Cogl we would rather not leak GLib api through Cogl's own api, except through explicitly namespaced cogl_glib_ / cogl_gtype_ feature apis. One of the benefits we see to not leaking GLib through Cogl's public API is that documentation for Cogl won't need to first introduce the Glib API to newcomers, thus hopefully lowering the barrier to learning Cogl. This patch provides a Cogl specific typedef for reporting runtime errors which by no coincidence matches the typedef for GError exactly. If Cogl is built with --enable-glib (default) then developers can even safely assume that a CoglError is a GError under the hood. This patch also enforces a consistent policy for when NULL is passed as an error argument and an error is thrown. In this case we log the error and abort the application, instead of silently ignoring it. In common cases where nothing has been implemented to handle a particular error and/or where applications are just printing the error and aborting themselves then this saves some typing. This also seems more consistent with language based exceptions which usually cause a program to abort if they are not explicitly caught (which passing a non-NULL error signifies in this case) Since this policy for NULL error pointers is stricter than the standard GError convention, there is a clear note in the documentation to warn developers that are used to using the GError api. Reviewed-by: Neil Roberts <neil@linux.intel.com> (cherry picked from commit b068d5ea09ab32c37e8c965fc8582c85d1b2db46) Note: Since we can't change the Cogl 1.x api the patch was changed to not rename _error_quark() functions to be _error_domain() functions and although it's a bit ugly, instead of providing our own CoglError type that's compatible with GError we simply #define CoglError to GError unless Cogl is built with glib disabled. Note: this patch does technically introduce an API break since it drops the cogl_error_get_type() symbol generated by glib-mkenum (Since the CoglError enum was replaced by a CoglSystemError enum) but for now we are assuming that this will not affect anyone currently using the Cogl API. If this does turn out to be a problem in practice then we would be able to fix this my manually copying an implementation of cogl_error_get_type() generated by glib-mkenum into a compatibility source file and we could also define the original COGL_ERROR_ enums for compatibility too. Note: another minor concern with cherry-picking this patch to the 1.14 branch is that an api scanner would be lead to believe that some APIs have changed, and for example the gobject-introspection parser which understands the semantics of GError will not understand the semantics of CoglError. We expect most people that have tried to use gobject-introspection with Cogl already understand though that it is not well suited to generating bindings of the Cogl api anyway and we aren't aware or anyone depending on such bindings for apis involving GErrors. (GnomeShell only makes very-very minimal use of Cogl via the gjs bindings for the cogl_rectangle and cogl_color apis.) The main reason we have cherry-picked this patch to the 1.14 branch even given the above concerns is that without it it would become very awkward for us to cherry-pick other beneficial patches from master. |
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Neil Roberts
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6a62e3077b |
sdl: Don't set SDL_GL_DOUBLEBUFFER when the swap chain has no pref
The ‘length’ for the swap chain is initially -1 which is supposed to mean ‘no preference’. However, both of the SDL winsys's were explicitly setting the SDL_GL_DOUBLEBUFFER attribute to zero in that case which would try to disable double buffering. On OS X, the equivalent to eglSwapBuffers (ie, [NSOpenGLContext flushBuffer]) does nothing for a single buffer context. The cogl-sdl-hello example does not specify the swap chain length so presumably it would end up with a single buffer config. When cogl_onscreen_swap_buffers is called it therefore does nothing and nothing is painted. I guess to make single-buffered contexts actually useful we should expose some public equivalent to glFlush so that you can ensure the rendering commands will actually hit the buffer. Alternatively we could document that cogl_onscreen_swap_buffers performs this task on single-buffered configs and then we could make the SDL winsys explicitly call glFlush in that case. Reviewed-by: Robert Bragg <robert@linux.intel.com> (cherry picked from commit 71e57f99002d5dee79bbd44b3bc57712b99acb55) |
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Neil Roberts
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df77e8565e |
Don't use eglGetProcAddress to retrieve core functions
According to the EGL spec, eglGetProcAddress should only be used to retrieve extension functions. It also says that returning non-NULL does not mean the extension is available so you could interpret this as saying that the function is allowed to return garbage for core functions. This seems to happen at least for the Android implementation of EGL. To workaround this the winsys's are now passed down a flag to say whether the function is from the core API. This information is already in the gl-prototypes headers as the minimum core GL version and as a pair of flags to specify whether it is available in core GLES1 and GLES2. If the function is in core the EGL winsys will now avoid using eglGetProcAddress and always fallback to querying the library directly with the GModule API. The GLX winsys is left alone because glXGetProcAddress apparently supports querying core API and extension functions. The WGL winsys could ideally be changed because wglGetProcAddress should also only be used for extension functions but the situation is slightly different because WGL considers anything from GL > 1.1 to be an extension so it would need a bit more information to determine whether to query the function directly from the library. The SDL winsys is also left alone because it's not as easy to portably determine which GL library SDL has chosen to load in order to resolve the symbols directly. Reviewed-by: Robert Bragg <robert@linux.intel.com> (cherry picked from commit 72089730ad06ccdd38a344279a893965ae68cec1) Since we aren't able to break API on the 1.12 branch cogl_get_proc_address is still supported but isn't easily able to determine whether the given name corresponds to a core symbol or not. For now we just assume the symbol being queried isn't part of the core GL api and update the documentation accordingly. |
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Neil Roberts
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17c818a9a7 |
Add an SDL2 winsys
This adds an alternate version of the SDL winsys using the SDL 2 API. The two versions are mutually exclusive and share the same CoglWinsysID. Version 2 of SDL fits a little bit better with Cogl because it supports multiple windows and the video subsystem can be initialised entirely independently of the rest of the subsystems. The SDL2 winsys creates an invisible dummy window in order to bind the GL context after creating the Cogl display. This is similar to how the X11 winsys's work. SDL2 seems to support compiling with support for both GL and GLES. However there doesn't seem to be a way to select between the two backends outside of SDL. In fact if you do compile them both in it seems to break down because it will always try to use the window system functions from the GLES backend because those are filled in second in the vtable. However when creating the window it will always prefer to use the GL function to choose a visual. This function gets confused because the GL backend has not been initialised at that point. The Cogl backend therefore just leaves it up to SDL to pick a sensible backend. It will then verify that it picked a GL library which matches the Cogl driver by checking the string from glGetString(GL_VERSION). Reviewed-by: Robert Bragg <robert@linux.intel.com> (cherry picked from commit 6cb5ab41355e7bfe28f367cf4afa39a7afcfeec2) |