Qt: Use GLES2 if enabled and GL isn't found

src/platform/qt/CMakeLists.txt

@@ -38,7 +38,13 @@ if(NOT Qt5OpenGL_FOUND OR NOT Qt5Widgets_FOUND OR NOT OPENGL_FOUND)
 	return()
 endif()
 
+if(BUILD_GL)
 list(APPEND PLATFORM_SRC ${PLATFORM_SRC} ${CMAKE_SOURCE_DIR}/src/platform/opengl/gl.c)
+endif()
+
+if(BUILD_GLES2)
+list(APPEND PLATFORM_SRC ${PLATFORM_SRC} ${CMAKE_SOURCE_DIR}/src/platform/opengl/gles2.c)
+endif()
 
 get_target_property(QT_TYPE Qt5::Core TYPE)
 if(QT_TYPE STREQUAL STATIC_LIBRARY)

src/platform/qt/DisplayGL.cpp

@@ -135,7 +135,11 @@ PainterGL::PainterGL(QGLWidget* parent)
 	, m_context(nullptr)
 	, m_messagePainter(nullptr)
 {
+#ifdef BUILD_GL
 	GBAGLContextCreate(&m_backend);
+#elif defined(BUILD_GLES2)
+	GBAGLES2ContextCreate(&m_backend);
+#endif
 	m_backend.d.swap = [](VideoBackend* v) {
 		PainterGL* painter = static_cast<PainterGL*>(v->user);
 		painter->m_gl->swapBuffers();

src/platform/qt/DisplayGL.h

@@ -14,7 +14,11 @@
 #include <QTimer>
 
 extern "C" {
+#ifdef BUILD_GL
 #include "platform/opengl/gl.h"
+#elif defined(BUILD_GLES2)
+#include "platform/opengl/gles2.h"
+#endif
 }
 
 struct GBAThread;
@@ -90,7 +94,11 @@ private:
 	QGLWidget* m_gl;
 	bool m_active;
 	GBAThread* m_context;
+#ifdef BUILD_GL
 	GBAGLContext m_backend;
+#elif defined(BUILD_GLES2)
+	GBAGLES2Context m_backend;
+#endif
 	QSize m_size;
 	MessagePainter* m_messagePainter;
 };