Platform: ability to request context version in GlutApplication.

src/Platform/GlutApplication.cpp

@@ -24,7 +24,10 @@
 
 #include "GlutApplication.h"
 
+#include <tuple>
+
 #include "Context.h"
+#include "Version.h"
 
 #include "Platform/ScreenedApplication.hpp"
 
@@ -75,6 +78,18 @@ bool GlutApplication::tryCreateContext(const Configuration& configuration) {
 
     glutInitDisplayMode(flags);
     glutInitWindowSize(configuration.size().x(), configuration.size().y());
+
+    /* Set context version, if requested */
+    if(configuration.version() != Version::None) {
+        Int major, minor;
+        std::tie(major, minor) = version(configuration.version());
+        glutInitContextVersion(major, minor);
+        #ifndef MAGNUM_TARGET_GLES
+        if(configuration.version() >= Version::GL310)
+            glutInitContextProfile(GLUT_CORE_PROFILE);
+        #endif
+    }
+
     if(!glutCreateWindow(configuration.title().data())) {
         Error() << "Platform::GlutApplication::tryCreateContext(): cannot create context";
         return false;

src/Platform/GlutApplication.h

@@ -290,6 +290,22 @@ class GlutApplication::Configuration {
             return *this;
         }
 
+        /** @brief Context version */
+        Version version() const { return _version; }
+
+        /**
+         * @brief Set context version
+         *
+         * If requesting version greater or equal to OpenGL 3.1, core profile
+         * is used. The created context will then have any version which is
+         * backwards-compatible with requested one. Default is
+         * @ref Version::None, i.e. any provided version is used.
+         */
+        Configuration& setVersion(Version version) {
+            _version = version;
+            return *this;
+        }
+
         /** @brief Sample count */
         Int sampleCount() const { return _sampleCount; }
 
@@ -310,6 +326,7 @@ class GlutApplication::Configuration {
         std::string _title;
         Vector2i _size;
         Int _sampleCount;
+        Version _version;
 };
 
 /**