Platform: ability to request context version in Sdl2Application.

src/Platform/Sdl2Application.cpp

@@ -24,11 +24,14 @@
 
 #include "Sdl2Application.h"
 
-#ifdef CORRADE_TARGET_EMSCRIPTEN
+#ifndef CORRADE_TARGET_EMSCRIPTEN
+#include <tuple>
+#else
 #include <emscripten/emscripten.h>
 #endif
 
 #include "Context.h"
+#include "Version.h"
 #include "Platform/ScreenedApplication.hpp"
 
 namespace Magnum { namespace Platform {
@@ -111,15 +114,30 @@ bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
 
     /** @todo Remove when Emscripten has proper SDL2 support */
     #ifndef CORRADE_TARGET_EMSCRIPTEN
+    /* Set context version, if requested */
+    if(configuration.version() != Version::None) {
+        Int major, minor;
+        std::tie(major, minor) = version(configuration.version());
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, major);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, minor);
+
+        #ifndef MAGNUM_TARGET_GLES
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, configuration.version() >= Version::GL310 ?
+            SDL_GL_CONTEXT_PROFILE_CORE : SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
+        #endif
+    }
+
     /* On OS X we need to create 3.2 context, as the default (2.1) contains
        compatibility features which are not implemented for newer GL versions
        in Apple's GL drivers, thus we would be forever stuck on 2.1 without the
        new features. In practice SDL fails to create 2.1 context on recent OS X
        versions. */
     #ifdef __APPLE__
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+    else {
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+    }
     #endif
 
     if(!(window = SDL_CreateWindow(configuration.title().data(),
@@ -295,7 +313,7 @@ Sdl2Application::Configuration::Configuration():
     #ifndef CORRADE_TARGET_EMSCRIPTEN
     _title("Magnum SDL2 Application"),
     #endif
-    _size(800, 600), _flags(Flag::Resizable), _sampleCount(0) {}
+    _size(800, 600), _flags(Flag::Resizable), _sampleCount(0), _version(Version::None) {}
 
 Sdl2Application::Configuration::~Configuration() = default;
 

src/Platform/Sdl2Application.h

@@ -448,6 +448,34 @@ class Sdl2Application::Configuration {
             return *this;
         }
 
+        #ifndef CORRADE_TARGET_EMSCRIPTEN
+        /**
+         * @brief Context version
+         *
+         * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         */
+        Version version() const { return _version; }
+        #endif
+
+        /**
+         * @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.
+         * @note In @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten" this function
+         *      does nothing (@ref Version::GLES200 is always used).
+         */
+        Configuration& setVersion(Version version) {
+            #ifndef CORRADE_TARGET_EMSCRIPTEN
+            _version = version;
+            #else
+            static_cast<void>(version);
+            #endif
+            return *this;
+        }
+
         /** @brief Sample count */
         Int sampleCount() const { return _sampleCount; }
 
@@ -470,6 +498,7 @@ class Sdl2Application::Configuration {
         Vector2i _size;
         Flags _flags;
         Int _sampleCount;
+        Version _version;
 };
 
 CORRADE_ENUMSET_OPERATORS(Sdl2Application::Configuration::Flags)