Add preliminary support for VR/OpenVR for HTC Vive and Oculus Rift,

(Windows-only first, later Linux and OSX)
Use premake to build, use --enable_openvr flag

examples/BasicDemo/premake4.lua

@@ -59,6 +59,7 @@ end
                           
 
 
+
 project "App_BasicExampleGuiWithSoftwareRenderer"
 
 if _OPTIONS["ios"] then
@@ -133,3 +134,62 @@ files {
 	"../TinyRenderer/TinyRenderer.cpp",
 	"../Utils/b3ResourcePath.cpp"
 }
+
+
+
+
+		if _OPTIONS["enable_openvr"] then
+
+project "App_BasicExampleVR"
+
+if _OPTIONS["ios"] then
+        kind "WindowedApp"
+else
+        kind "ConsoleApp"
+end
+defines {"B3_USE_STANDALONE_EXAMPLE","BT_ENABLE_VR"}
+
+
+
+includedirs {"../../src", 
+					"../ThirdPartyLibs/openvr/headers",
+					"../ThirdPartyLibs/openvr/samples/shared"}
+
+links {
+        "BulletDynamics","BulletCollision", "LinearMath", "OpenGL_Window","Bullet3Common", "openvr_api"
+}
+
+	initOpenGL()
+  initGlew()
+
+
+language "C++"
+
+files {
+        "BasicExample.cpp",
+        "*.h",
+        "../StandaloneMain/hellovr_opengl_main.cpp",
+				"../ExampleBrowser/OpenGLGuiHelper.cpp",
+				"../ExampleBrowser/GL_ShapeDrawer.cpp",
+				"../ExampleBrowser/CollisionShape2TriangleMesh.cpp",
+				"../ThirdPartyLibs/openvr/samples/shared/lodepng.cpp",
+				"../ThirdPartyLibs/openvr/samples/shared/lodepng.h",
+				"../ThirdPartyLibs/openvr/samples/shared/Matrices.cpp",
+				"../ThirdPartyLibs/openvr/samples/shared/Matrices.h",
+				"../ThirdPartyLibs/openvr/samples/shared/pathtools.cpp",
+				"../ThirdPartyLibs/openvr/samples/shared/pathtools.h",
+				"../ThirdPartyLibs/openvr/samples/shared/Vectors.h",
+				
+}
+
+if os.is("Windows") then 
+	libdirs {"../ThirdPartyLibs/openvr/lib/win32"}
+end
+
+if os.is("Linux") then initX11() end
+
+if os.is("MacOSX") then
+        links{"Cocoa.framework"}
+end
+
+end