X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fscreen%2Fextensions.cxx;h=130673c51f92c7654a1ba47c36b865a4ce14c3e5;hb=bbd61977f14c30ce93a2bcf5a3551708d36a29c8;hp=9a6de53b243d3bea0d3ef116e03c2c54e8177b48;hpb=73cb6ff00d8ad7112cec623452fc1d2c4a523fdf;p=simgear.git

diff --git a/simgear/screen/extensions.cxx b/simgear/screen/extensions.cxx
index 9a6de53b..130673c5 100644
--- a/simgear/screen/extensions.cxx
+++ b/simgear/screen/extensions.cxx
@@ -26,6 +26,9 @@
 
 #include "extensions.hxx"
 #include <simgear/debug/logstream.hxx>
+#if !defined(WIN32)
+#  include <dlfcn.h>
+#endif
 
 bool SGSearchExtensionsString(const char *extString, const char *extName) {
     // Returns GL_TRUE if the *extName string appears in the *extString string,
@@ -53,7 +56,7 @@ bool SGSearchExtensionsString(const char *extString, const char *extName) {
     return GL_FALSE;
 }
 
-bool SGIsOpenGLExtensionSupported(char *extName) {
+bool SGIsOpenGLExtensionSupported(const char *extName) {
    // Returns GL_TRUE if the OpenGL Extension whose name is *extName
    // is supported by the system, or GL_FALSE otherwise.
    //
@@ -100,6 +103,7 @@ void* macosxGetGLProcAddress(const char *func) {
 
 void *SGGetGLProcAddress(const char *func) {
     static void *libHandle = NULL;
+    static void *(*glXGetProcAddressPtr)(const GLubyte*) = 0;
     void *fptr = NULL;
 
     /*
@@ -107,20 +111,37 @@ void *SGGetGLProcAddress(const char *func) {
      */
     dlerror();
 
-    if (libHandle == NULL)
-        libHandle = dlopen("libGL.so", RTLD_LAZY);
+    /*
+     * Since libGL must be linked to the binary we run on, this is the
+     * right handle. That 'current binary' handle also avoids conflicts which
+     * arise from linking with a different libGL at link time an than later
+     * use the standard libGL at runtime ...
+     */
+    if (libHandle == NULL) {
+        libHandle = dlopen(NULL, RTLD_LAZY);
+
+        if (!libHandle) {
+            const char *error = dlerror();
+            if (error) {
+                SG_LOG(SG_GENERAL, SG_INFO, error);
+                return 0;
+            }
+        }
+
+        void* symbol = dlsym(libHandle, "glXGetProcAddress");
+        if (!symbol)
+            symbol = dlsym(libHandle, "glXGetProcAddressARB");
+        glXGetProcAddressPtr = (void *(*)(const GLubyte*)) symbol;
+    }
 
-    if (libHandle == NULL)
-        libHandle = dlopen("libGL.so.1", RTLD_LAZY);
+    // First try the glx api function for that
+    if (glXGetProcAddressPtr) {
+        fptr = glXGetProcAddressPtr((const GLubyte*)func);
 
-    if (libHandle != NULL) {
+    } else if (libHandle != NULL) {
         fptr = dlsym(libHandle, func);
 
-#if defined (__FreeBSD__)
         const char *error = dlerror();
-#else
-        char *error = dlerror();
-#endif
         if (error)
             SG_LOG(SG_GENERAL, SG_INFO, error);
     }