1 files changed, 51 insertions, 0 deletions
diff --git a/canvas/opengl/rectangularMultiColorGradientFragmentShader.glsl b/canvas/opengl/rectangularMultiColorGradientFragmentShader.glsl
new file mode 100644
index 000000000..ea17565c1
--- /dev/null
+++ b/canvas/opengl/rectangularMultiColorGradientFragmentShader.glsl
@@ -0,0 +1,51 @@
+/* -*- 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 120
+
+uniform int       i_nColors;
+uniform sampler1D t_colorArray4d;
+uniform sampler1D t_stopArray1d;
+uniform mat3x2    m_transform;
+varying vec2      v_textureCoords2d;
+
+int max(int x, int y)
+{
+    if(x > y)
+        return x;
+    return y;
+}
+
+int findBucket(float t)
+{
+    int nMinBucket=0;
+    while( nMinBucket < i_nColors &&
+            texture1D(t_stopArray1d, nMinBucket).s < t )
+        ++nMinBucket;
+    return max(nMinBucket-1,0);
+}
+
+void main(void)
+{
+    vec2  v = abs( vec2(m_transform * vec3(v_textureCoords2d,1)) );
+    float fAlpha = 1 - max(v.x, v.y);
+
+    int nMinBucket=findBucket( fAlpha );
+
+    float fLerp =
+        (fAlpha-texture1D(t_stopArray1d, nMinBucket).s) /
+        (texture1D(t_stopArray1d, nMinBucket+1).s -
+         texture1D(t_stopArray1d, nMinBucket).s);
+
+    gl_FragColor = mix(texture1D(t_colorArray4d, nMinBucket),
+            texture1D(t_colorArray4d, nMinBucket+1),
+            fLerp);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */