1 files changed, 37 insertions, 0 deletions
diff --git a/vcl/opengl/shaders/lineVertexShader.glsl b/vcl/opengl/shaders/lineVertexShader.glsl
new file mode 100644
index 000000000..e26be78d0
--- /dev/null
+++ b/vcl/opengl/shaders/lineVertexShader.glsl
@@ -0,0 +1,37 @@
+/* -*- 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/.
+ */
+
+attribute vec2 position;
+attribute vec4 extrusion_vectors;
+
+varying float fade_factor; // fade factor for anti-aliasing
+
+uniform float line_width;
+uniform float feather; // width where we fade the line
+
+uniform mat4 mvp;
+
+void main()
+{
+   vec2 extrusion_vector = extrusion_vectors.xy;
+   // miter factor to additionally lengthen the distance of vertex (needed for miter)
+   // if 1.0 - miter_factor has no effect
+   float miter_factor = 1.0f / abs(extrusion_vectors.z);
+   // fade factor is always -1.0 or 1.0 -> we transport that info together with length
+   fade_factor = sign(extrusion_vectors.z);
+
+   float rendered_thickness = (line_width + feather * 2.0) * miter_factor;
+
+   // lengthen the vertex in direction of the extrusion vector by line width.
+   vec4 position = vec4(position + (extrusion_vector * (rendered_thickness / 2.0) ), 0.0, 1.0);
+
+   gl_Position = mvp * position;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */