X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fscreen%2Fextensions.cxx;h=130673c51f92c7654a1ba47c36b865a4ce14c3e5;hb=bbd61977f14c30ce93a2bcf5a3551708d36a29c8;hp=21db7136409c915265aae8504bd0edb9c9eb47e7;hpb=5034346b67d853b11de71677b677dea2df597a95;p=simgear.git

diff --git a/simgear/screen/extensions.cxx b/simgear/screen/extensions.cxx
index 21db7136..130673c5 100644
--- a/simgear/screen/extensions.cxx
+++ b/simgear/screen/extensions.cxx
@@ -26,12 +26,15 @@
 
 #include "extensions.hxx"
 #include <simgear/debug/logstream.hxx>
+#if !defined(WIN32)
+#  include <dlfcn.h>
+#endif
 
-static bool SGSearchExtensionsString(char *extString, char *extName) {
+bool SGSearchExtensionsString(const char *extString, const char *extName) {
     // Returns GL_TRUE if the *extName string appears in the *extString string,
     // surrounded by white spaces, or GL_FALSE otherwise.
 
-    char *p, *end;
+    const char *p, *end;
     int n, extNameLen;
 
     if ((extString == NULL) || (extName == NULL))
@@ -53,15 +56,14 @@ static bool SGSearchExtensionsString(char *extString, 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.
    //
    // The *extName string must follow the OpenGL extensions naming scheme
    // (ie: "GL_type_extension", like GL_EXT_convolution)
 
-    return SGSearchExtensionsString((char *)glGetString(GL_EXTENSIONS),
-extName);
+    return SGSearchExtensionsString((const char *)glGetString(GL_EXTENSIONS),extName);
 }
 
 #ifdef __APPLE__
@@ -97,10 +99,11 @@ void* macosxGetGLProcAddress(const char *func) {
   return function;
 }
 
-#else if !defined( WIN32 )
+#elif !defined( WIN32 )
 
 void *SGGetGLProcAddress(const char *func) {
     static void *libHandle = NULL;
+    static void *(*glXGetProcAddressPtr)(const GLubyte*) = 0;
     void *fptr = NULL;
 
     /*
@@ -108,13 +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;
+    }
+
+    // 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);
 
-        char *error = dlerror();
+        const char *error = dlerror();
         if (error)
             SG_LOG(SG_GENERAL, SG_INFO, error);
     }