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Fix glewContextInit on core context

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This commit is contained in:
Turo Lamminen 2014-12-22 00:17:40 +02:00
parent cbe15308bf
commit c8fea198b3
2 changed files with 40 additions and 2 deletions
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2
auto/src/glew_head.c
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@ -6,7 +6,9 @@
# include <GL/glxew.h>
#endif
#include <alloca.h>
#include <stddef.h> /* For size_t */
#include <string.h>
/*
* Define glewGetContext and related helper macros.

40
auto/src/glew_init_gl.c
View File

@ -66,8 +66,44 @@ GLenum GLEWAPIENTRY glewContextInit (GLEW_CONTEXT_ARG_DEF_LIST)
/* query opengl extensions string */
extStart = glGetString(GL_EXTENSIONS);
if (extStart == 0)
extStart = (const GLubyte*)"";
if (extStart == 0) {
/* no extension string, we're probably on a core context
build it manually */
GLint numExtensions = 0;
glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);
/* don't have real glGetStringi yet... */
PFNGLGETSTRINGIPROC tempGetStringi = (PFNGLGETSTRINGIPROC)glewGetProcAddress((const GLubyte*)"glGetStringi");
if (numExtensions != 0 && tempGetStringi != 0)
{
int i;
size_t extStrLen = 0;
char *extStringTemp;
/* calculate length */
for (i = 0; i < numExtensions; i++)
{
const GLubyte* extName = tempGetStringi(GL_EXTENSIONS, i);
/* +1 is for space separator */
extStrLen += _glewStrLen(extName) + 1;
}
/* need one extra for the '\0' -terminator */
extStrLen += 1;
/* allocate extension string on the stack */
extStringTemp = alloca(extStrLen);
memset(extStringTemp, 0, extStrLen);
extStart = (const GLubyte *) extStringTemp;
for (i = 0; i < numExtensions; i++)
{
const GLubyte* extName = tempGetStringi(GL_EXTENSIONS, i);
strcat(extStringTemp, (const char *) extName);
/* be efficient, avoid O(n^2) behavior */
extStringTemp += _glewStrLen(extName);
strcat(extStringTemp, " ");
extStringTemp += 1;
}
}
}
extEnd = extStart + _glewStrLen(extStart);
/* initialize extensions */