Backends: OpenGL3: Update GL3W based imgui_impl_opengl3_loader.h to load "libGL.so" instead of "libGL.so.1". (#6983)

backends/imgui_impl_opengl3.cpp

@@ -22,6 +22,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-11-08: OpenGL: Update GL3W based imgui_impl_opengl3_loader.h to load "libGL.so" instead of "libGL.so.1", accomodating for NetBSD systems having only "libGL.so.3" available. (#6983)
 //  2023-10-05: OpenGL: Rename symbols in our internal loader so that LTO compilation with another copy of gl3w is possible. (#6875, #6668, #4445)
 //  2023-06-20: OpenGL: Fixed erroneous use glGetIntegerv(GL_CONTEXT_PROFILE_MASK) on contexts lower than 3.2. (#6539, #6333)
 //  2023-05-09: OpenGL: Support for glBindSampler() backup/restore on ES3. (#6375)

backends/imgui_impl_opengl3_loader.h

@@ -118,7 +118,7 @@ extern "C" {
 ** included as <GL/glcorearb.h>.
 **
 ** glcorearb.h includes only APIs in the latest OpenGL core profile
-** implementation together with APIs in newer ARB extensions which 
+** implementation together with APIs in newer ARB extensions which
 ** can be supported by the core profile. It does not, and never will
 ** include functionality removed from the core profile, such as
 ** fixed-function vertex and fragment processing.
@@ -666,7 +666,8 @@ static GL3WglProc (*glx_get_proc_address)(const GLubyte *);
 
 static int open_libgl(void)
 {
-    libgl = dlopen("libGL.so.1", RTLD_LAZY | RTLD_LOCAL);
+    // While most systems use libGL.so.1, NetBSD seems to use that libGL.so.3. See https://github.com/ocornut/imgui/issues/6983
+    libgl = dlopen("libGL.so", RTLD_LAZY | RTLD_LOCAL);
     if (!libgl)
         return GL3W_ERROR_LIBRARY_OPEN;
     *(void **)(&glx_get_proc_address) = dlsym(libgl, "glXGetProcAddressARB");

docs/CHANGELOG.txt

@@ -218,6 +218,8 @@ Other changes:
   doesn't emit it (same behavior as GLFW/SDL). (#6859) [@thedmd, @SuperWangKai]
 - Backends: OpenGL3: rename symbols in our internal loader so that LTO compilation with another
   copy of gl3w becomes possible. (#6875, #6668, #4445) [@nicolasnoble]
+- Backends: OpenGL3: Update GL3W based imgui_impl_opengl3_loader.h to load "libGL.so" instead
+  of "libGL.so.1", accomodating for NetBSD systems having only "libGL.so.3" available. (#6983)
 - Backends: OSX: Added support for F13 to F20 function keys. Support mapping F13 to PrintScreen. (#6891)
 - Internals: Renamed ImFloor() to ImTrunc(). Renamed ImFloorSigned() to ImFloor(). (#6861)