use vr hiddenarea mask

shaders/hiddenarea.frag

@@ -0,0 +1,15 @@
+#include <common>
+
+layout(location = 0) out vec4 out_color;
+#if MOTIONBLUR_ENABLED
+layout(location = 1) out vec4 out_motion;
+#endif
+
+void main()
+{
+out_color = vec4(vec3(0.0f), 1.0f);
+#if MOTIONBLUR_ENABLED
+	out_motion = vec4(0.0f);
+#endif
+gl_FragDepth = 1.0f;
+}

shaders/hiddenarea.vert

@@ -0,0 +1,6 @@
+layout(location = 0) in vec3 v_vert;
+
+void main()
+{
+	gl_Position = vec4(v_vert.xy * 2.0f - 1.0f, 0.5f, 1.0f);
+}