slideshow: Improve the performances of the Honeycomb transition

Change-Id: Iacddc7b84bf0be8bb112cba88cc7fd36f72e7ca0

1 files changed, 64 insertions, 0 deletions

diff --git a/slideshow/opengl/honeycombGeometryShader.glsl b/slideshow/opengl/honeycombGeometryShader.glsl
new file mode 100644
index 000000000000..bb2b1f3b3c78
--- /dev/null
+++ b/slideshow/opengl/honeycombGeometryShader.glsl
@@ -0,0 +1,64 @@
+/* -*- 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 150
+
+layout(triangles) in;
+layout(triangle_strip, max_vertices=13) out;
+
+in mat4 modelViewProjectionMatrix[];
+
+uniform float hexagonSize;
+uniform sampler2D permTexture;
+
+out vec2 texturePosition;
+out float fuzz;
+out vec2 v_center;
+
+const float expandFactor = 0.0318;
+
+float snoise(vec2 p)
+{
+    return texture2D(permTexture, p).r;
+}
+
+void emitHexagonVertex(vec3 center, vec2 translation)
+{
+    vec4 pos = vec4(center + hexagonSize * expandFactor * vec3(translation, 0.0), 1.0);
+    gl_Position = modelViewProjectionMatrix[0] * pos;
+    texturePosition = vec2((pos.x + 1), (1 - pos.y)) / 2;
+    EmitVertex();
+}
+
+void main()
+{
+    vec2 translateVectors[6];
+    translateVectors[0] = vec2(-3, -2);
+    translateVectors[1] = vec2(0, -4);
+    translateVectors[2] = vec2(3, -2);
+    translateVectors[3] = vec2(3, 2);
+    translateVectors[4] = vec2(0, 4);
+    translateVectors[5] = vec2(-3, 2);
+
+    vec3 center = gl_in[0].gl_Position.xyz;
+
+    v_center = (1 + center.xy) / 2;
+    fuzz = snoise(center.xy);
+
+    emitHexagonVertex(center, translateVectors[5]);
+
+    for (int i = 0; i < 6; ++i) {
+        emitHexagonVertex(center, translateVectors[i]);
+        emitHexagonVertex(center, vec2(0, 0));
+    }
+
+    EndPrimitive();
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */