mirror of
https://github.com/nigels-com/glew.git
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91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
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/* ------------------------------------------------------------------------- */
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/*
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* GLEW, just like OpenGL or GLU, does not rely on the standard C library.
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* These functions implement the functionality required in this file.
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*/
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static int _glewStrLen (const char *s)
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{
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int i=0;
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while (s+i != NULL && s[i] != '\0') i++;
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return i;
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}
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static int _glewStrCLen (const char *s, char c)
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{
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int i=0;
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while (s+i != NULL && s[i] != '\0' && s[i] != c) i++;
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return i;
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}
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static int _glewStrSame (const char *a, const char *b, int n)
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{
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int i=0;
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while (i < n && a+i != NULL && b+i != NULL && a[i] == b[i]) i++;
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return i == n;
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}
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/*
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* Search for name in the extensions string. Use of strstr()
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* is not sufficient because extension names can be prefixes of
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* other extension names. Could use strtok() but the constant
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* string returned by glGetString might be in read-only memory.
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*/
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GLboolean glewGetExtension (const char *name)
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{
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char *p, *end;
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int len = _glewStrLen(name);
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p = (char*)glGetString(GL_EXTENSIONS);
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if (0 == p) return GL_FALSE;
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end = p + _glewStrLen(p);
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while (p < end)
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{
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int n = _glewStrCLen(p, ' ');
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if (len == n && _glewStrSame(name, p, n)) return GL_TRUE;
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p += n+1;
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}
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return GL_FALSE;
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}
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/* ------------------------------------------------------------------------- */
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static GLuint _glewInit ()
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{
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char* s;
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int i;
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/* query opengl version */
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s = (char*)glGetString(GL_VERSION);
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if (!s) return GLEW_ERROR_NO_GL_VERSION;
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i=_glewStrCLen(s, '.')+1;
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if (s+i == NULL || s[i] < '1')
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{
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return GLEW_ERROR_GL_VERSION_10_ONLY;
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}
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else
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{
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if (s[2] == '4')
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{
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GLEW_VERSION_1_1 = GL_TRUE;
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GLEW_VERSION_1_2 = GL_TRUE;
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GLEW_VERSION_1_3 = GL_TRUE;
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GLEW_VERSION_1_4 = GL_TRUE;
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}
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if (s[2] == '3')
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{
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GLEW_VERSION_1_1 = GL_TRUE;
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GLEW_VERSION_1_2 = GL_TRUE;
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GLEW_VERSION_1_3 = GL_TRUE;
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}
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if (s[2] == '2')
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{
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GLEW_VERSION_1_1 = GL_TRUE;
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GLEW_VERSION_1_2 = GL_TRUE;
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}
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if (s[2] < '2')
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{
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GLEW_VERSION_1_1 = GL_TRUE;
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}
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}
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/* initialize extensions */
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