From 1b2b08c5f3a5941151a2f4a8c5da7f214ee979e4 Mon Sep 17 00:00:00 2001 From: Chia-I Wu Date: Fri, 5 Feb 2010 12:44:45 +0800 Subject: docs: Update the developer section of egl.html. Mainly to add a subsection about EGL_RENDER_BUFFER. --- docs/egl.html | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'docs') diff --git a/docs/egl.html b/docs/egl.html index cdfae044a8..9eba402411 100644 --- a/docs/egl.html +++ b/docs/egl.html @@ -267,6 +267,41 @@ uninitialized display.

resources. The drivers are responsible to the correct behavior as defined by EGL.

+

EGL_RENDER_BUFFER

+ +

In EGL, the color buffer a context should try to render to is decided by the +binding surface. It should try to render to the front buffer if the binding +surface has EGL_RENDER_BUFFER set to +EGL_SINGLE_BUFFER; If the same context is later bound to a +surface with EGL_RENDER_BUFFER set to +EGL_BACK_BUFFER, the context should try to render to the back +buffer. However, the context is allowed to make the final decision as to which +color buffer it wants to or is able to render to.

+ +

For pbuffer surfaces, the render buffer is always +EGL_BACK_BUFFER. And for pixmap surfaces, the render buffer is +always EGL_SINGLE_BUFFER. Unlike window surfaces, EGL spec +requires their EGL_RENDER_BUFFER values to be honored. As a +result, a driver should never set EGL_PIXMAP_BIT or +EGL_PBUFFER_BIT bits of a config if the contexts created with the +config won't be able to honor the EGL_RENDER_BUFFER of pixmap or +pbuffer surfaces.

+ +

It should also be noted that pixmap and pbuffer surfaces are assumed to be +single-buffered, in that eglSwapBuffers has no effect on them. It +is desirable that a driver allocates a private color buffer for each pbuffer +surface created. If the window system the driver supports has native pbuffers, +or if the native pixmaps have more than one color buffers, the driver should +carefully attach the native color buffers to the EGL surfaces, re-route them if +required.

+ +

There is no defined behavior as to, for example, how +glDrawBuffer interacts with EGL_RENDER_BUFFER. Right +now, it is desired that the draw buffer in a client API be fixed for pixmap and +pbuffer surfaces. Therefore, the driver is responsible to guarantee that the +client API renders to the specified render buffer for pixmap and pbuffer +surfaces.

+

TODOs