1 files changed, 57 insertions, 0 deletions
diff --git a/slideshow/opengl/rippleFragmentShader.glsl b/slideshow/opengl/rippleFragmentShader.glsl
new file mode 100644
index 000000000..df4bd5927
--- /dev/null
+++ b/slideshow/opengl/rippleFragmentShader.glsl
@@ -0,0 +1,57 @@
+/* -*- 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
+
+#define M_PI 3.1415926535897932384626433832795
+
+uniform sampler2D leavingSlideTexture;
+uniform sampler2D enteringSlideTexture;
+uniform float time;
+uniform vec2 center;
+uniform float slideRatio;
+
+varying vec2 v_texturePosition;
+
+// This function returns the distance between two points, taking into account the slide ratio.
+float betterDistance(vec2 p1, vec2 p2)
+{
+    p1.x *= slideRatio;
+    p2.x *= slideRatio;
+    return distance(p1, p2);
+}
+
+void main()
+{
+    const float w = 0.5;
+    const float v = 0.1;
+
+    // Distance from this fragment to the center, in slide coordinates.
+    float dist = betterDistance(center, v_texturePosition);
+
+    // We want the ripple to span all of the slide at the end of the transition.
+    float t = time * (sqrt(2.0) * (slideRatio < 1.0 ? 1.0 / slideRatio : slideRatio));
+
+    // Interpolate the distance to the center in function of the time.
+    float mixed = smoothstep(t*w-v, t*w+v, dist);
+
+    // Get the displacement offset from the current pixel, for fragments that have been touched by the ripple already.
+    vec2 offset = (v_texturePosition - center) * (sin(dist * 64.0 - time * 16.0) + 0.5) / 32.0;
+    vec2 wavyTexCoord = mix(v_texturePosition + offset, v_texturePosition, time);
+
+    // Get the final position we will sample from.
+    vec2 pos = mix(wavyTexCoord, v_texturePosition, mixed);
+
+    // Sample from the textures and mix that together.
+    vec4 leaving = texture2D(leavingSlideTexture, pos);
+    vec4 entering = texture2D(enteringSlideTexture, pos);
+    gl_FragColor = mix(entering, leaving, mixed);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */