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Issue
8381001:
Split GL binding init into core and extension part (Closed)
DescriptionSplit GL binding init into core and extension part
This change splits the GL binding initialization into to phases: core
functions and extension functions. This is motivated by two
peculiarities of the EGL window binding layer:
1. Pointers to core GL entry points may not be queried through
eglGetProcAddress().
2. The return value of eglGetProcAddress() is not specified to be NULL
for unsupported functions.
In light of these limitations, the current strategy of blindly querying
all GL entry points from eglGetProcAddress() and falling back to dlsym()
results in bogus function pointers on some EGL implementations.
This patch fixes the problem as follows:
1. Add GetGLCoreProcAddress() that only queries dlsym() and use it to
initialize pointers to all entry points. On EGL based platforms
pointers to extension functions will most likely be NULL at this
point.
2. When a context is first made current, look up the set of supported
extensions and use GetGLProcAddress() to populate the remaining
extension function pointers.
The reworked GL bindings generator uses the standard Khronos headers to
recognize the extension functions and produce appropriate initialization
code.
Note that the patch also updates gl2ext.h to match the upstream Khronos
version and corrects some minor errors in the downstream changes.
BUG=5427391
TEST=
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=107602
Patch Set 1 #Patch Set 2 : Use existing glext.h/wglext.h/glxext.h headers from Mesa. #
Total comments: 2
Patch Set 3 : Added dependencies to gl.gyp. Used NOT_REACHED() instead of DCHECK(0). #
Messages
Total messages: 8 (0 generated)
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