extern void (GLAPIENTRY *qglTexImage2D)(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels );
extern void (GLAPIENTRY *qglTexSubImage2D)(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels);
extern void (GLAPIENTRY *qglDeleteTextures)(GLsizei n, const GLuint *textures);
extern void (GLAPIENTRY *qglTexImage2D)(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels );
extern void (GLAPIENTRY *qglTexSubImage2D)(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels);
extern void (GLAPIENTRY *qglDeleteTextures)(GLsizei n, const GLuint *textures);