1 files changed, 25 insertions, 0 deletions
diff --git a/vcl/opengl/shaders/invert50FragmentShader.glsl b/vcl/opengl/shaders/invert50FragmentShader.glsl
new file mode 100644
index 000000000..9222888f0
--- /dev/null
+++ b/vcl/opengl/shaders/invert50FragmentShader.glsl
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#version 130
+
+/*precision mediump float;*/
+
+void main() {
+    vec2 tex_mod = mod(gl_FragCoord, 2).xy;
+    bool bLeft = (tex_mod.x > 0.0) && (tex_mod.x < 1.0);
+    bool bTop = (tex_mod.y > 0.0) && (tex_mod.y < 1.0);
+    // horrors - where is the XOR operator ?
+    if ((bTop && bLeft) || (!bTop && !bLeft))
+        gl_FragColor = vec4(255,255,255,0);
+    else
+        gl_FragColor = vec4(0,0,0,0);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */