+#define GL_DEPTH_COMPONENT 0x1902
+#define GL_VIEWPORT 0x0BA2
+#define GL_DRAW_BUFFER 0x0C01
+#define GL_READ_BUFFER 0x0C02
+#define GL_LUMINANCE 0x1909
+#define GL_INTENSITY 0x8049
+
+#endif
+
+//GL_EXT_texture_filter_anisotropic
+extern int gl_support_anisotropy;
+extern int gl_max_anisotropy;
+#ifndef GL_TEXTURE_MAX_ANISOTROPY_EXT
+#define GL_TEXTURE_MAX_ANISOTROPY_EXT 0x84FE
+#define GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT 0x84FF
+#endif
+
+// GL_ARB_depth_texture
+#ifndef GL_DEPTH_COMPONENT32_ARB
+#define GL_DEPTH_COMPONENT16_ARB 0x81A5
+#define GL_DEPTH_COMPONENT24_ARB 0x81A6
+#define GL_DEPTH_COMPONENT32_ARB 0x81A7
+#define GL_TEXTURE_DEPTH_SIZE_ARB 0x884A
+#define GL_DEPTH_TEXTURE_MODE_ARB 0x884B
+#endif
+
+// GL_ARB_shadow
+extern int gl_support_arb_shadow;
+#ifndef GL_TEXTURE_COMPARE_MODE_ARB
+#define GL_TEXTURE_COMPARE_MODE_ARB 0x884C
+#define GL_TEXTURE_COMPARE_FUNC_ARB 0x884D
+#define GL_COMPARE_R_TO_TEXTURE_ARB 0x884E