Qt: Relax hard dependency on OpenGL.

src/platform/qt/CMakeLists.txt

@@ -35,12 +35,10 @@ find_package(Qt5OpenGL)
 find_package(Qt5Widgets)
 
 if(NOT BUILD_GL AND NOT BUILD_GLES2)
-	message(WARNING "OpenGL is required to build the Qt port")
-	set(BUILD_QT OFF PARENT_SCOPE)
-	return()
+	message(WARNING "OpenGL is recommended to build the Qt port")
 endif()
 
-if(NOT Qt5OpenGL_FOUND OR NOT Qt5Widgets_FOUND)
+if(NOT Qt5Widgets_FOUND)
 	message(WARNING "Cannot find Qt modules")
 	set(BUILD_QT OFF PARENT_SCOPE)
 	return()
@@ -243,8 +241,11 @@ qt5_wrap_ui(UI_SRC ${UI_FILES})
 add_executable(${BINARY_NAME}-qt WIN32 MACOSX_BUNDLE main.cpp ${CMAKE_SOURCE_DIR}/res/mgba.icns ${SOURCE_FILES} ${PLATFORM_SRC} ${UI_SRC} ${AUDIO_SRC} ${RESOURCES})
 set_target_properties(${BINARY_NAME}-qt PROPERTIES MACOSX_BUNDLE_INFO_PLIST ${CMAKE_SOURCE_DIR}/res/info.plist.in COMPILE_DEFINITIONS "${FEATURE_DEFINES};${FUNCTION_DEFINES};${OS_DEFINES};${QT_DEFINES}")
 
-list(APPEND QT_LIBRARIES Qt5::Widgets Qt5::OpenGL)
-target_link_libraries(${BINARY_NAME}-qt ${PLATFORM_LIBRARY} ${BINARY_NAME} ${QT_LIBRARIES} ${OPENGL_LIBRARY} ${OPENGLES2_LIBRARY})
+list(APPEND QT_LIBRARIES Qt5::Widgets)
+if(BUILD_GL OR BUILD_GLES2)
+	list(APPEND QT_LIBRARIES Qt5::OpenGL ${OPENGL_LIBRARY} ${OPENGLES2_LIBRARY})
+endif()
+target_link_libraries(${BINARY_NAME}-qt ${PLATFORM_LIBRARY} ${BINARY_NAME} ${QT_LIBRARIES})
 set(CPACK_DEBIAN_PACKAGE_DEPENDS "${CPACK_DEBIAN_PACKAGE_DEPENDS}" PARENT_SCOPE)
 
 install(TARGETS ${BINARY_NAME}-qt

src/platform/qt/DisplayGL.cpp

@@ -5,6 +5,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "DisplayGL.h"
 
+#if defined(BUILD_GL) || defined(BUILD_GLES)
+
 #include <QApplication>
 #include <QResizeEvent>
 #include <QTimer>
@@ -483,3 +485,5 @@ void PainterGL::clearShaders() {
 VideoShader* PainterGL::shaders() {
 	return &m_shader;
 }
+
+#endif

src/platform/qt/DisplayGL.h

@@ -6,6 +6,8 @@
 #ifndef QGBA_DISPLAY_GL
 #define QGBA_DISPLAY_GL
 
+#if defined(BUILD_GL) || defined(BUILD_GLES)
+
 #include "Display.h"
 
 #ifdef USE_EPOXY
@@ -128,3 +130,5 @@ private:
 }
 
 #endif
+
+#endif