1 files changed, 111 insertions, 0 deletions
diff --git a/slideshow/opengl/honeycombGeometryShader.glsl b/slideshow/opengl/honeycombGeometryShader.glsl
new file mode 100644
index 000000000..dedc0df97
--- /dev/null
+++ b/slideshow/opengl/honeycombGeometryShader.glsl
@@ -0,0 +1,111 @@
+/* -*- 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=27) out;
+
+in mat4 projectionMatrix[];
+in mat4 modelViewMatrix[];
+in mat4 shadowMatrix[];
+
+uniform float hexagonSize;
+uniform sampler2D permTexture;
+
+out vec2 texturePosition;
+out float fuzz;
+out vec2 v_center;
+out vec3 normal;
+out vec4 shadowCoordinate;
+
+const float expandFactor = 0.0318;
+
+float snoise(vec2 p)
+{
+    return texture(permTexture, p).r;
+}
+
+mat4 identityMatrix(void)
+{
+    return mat4(1.0, 0.0, 0.0, 0.0,
+                0.0, 1.0, 0.0, 0.0,
+                0.0, 0.0, 1.0, 0.0,
+                0.0, 0.0, 0.0, 1.0);
+}
+
+mat4 scaleMatrix(vec3 axis)
+{
+    mat4 matrix = identityMatrix();
+    matrix[0][0] = axis.x;
+    matrix[1][1] = axis.y;
+    matrix[2][2] = axis.z;
+    return matrix;
+}
+
+mat4 translationMatrix(vec3 axis)
+{
+    mat4 matrix = identityMatrix();
+    matrix[3] = vec4(axis, 1.0);
+    return matrix;
+}
+
+void emitHexagonVertex(vec3 center, vec2 translation)
+{
+    vec4 pos = vec4(center + hexagonSize * expandFactor * vec3(translation, 0.0), 1.0);
+    gl_Position = projectionMatrix[0] * modelViewMatrix[0] * pos;
+    shadowCoordinate = translationMatrix(vec3(0.5, 0.5, 0.5)) * scaleMatrix(vec3(0.5, 0.5, 0.5)) * shadowMatrix[0] * modelViewMatrix[0] * pos;
+    texturePosition = vec2((pos.x + 1), (1 - pos.y)) / 2;
+    EmitVertex();
+}
+
+void main()
+{
+    const vec2 translateVectors[6] = vec2[](
+        vec2(-3, -2),
+        vec2(0, -4),
+        vec2(3, -2),
+        vec2(3, 2),
+        vec2(0, 4),
+        vec2(-3, 2)
+    );
+
+    vec3 center = gl_in[0].gl_Position.xyz;
+
+    v_center = (1 + center.xy) / 2;
+    fuzz = snoise(center.xy);
+
+    // Draw “walls” to the hexagons.
+    if (hexagonSize < 1.0) {
+        vec3 rearCenter = vec3(center.xy, -0.3);
+        normal = vec3(0.0, 0.0, 0.3);
+        emitHexagonVertex(center, translateVectors[5]);
+        emitHexagonVertex(rearCenter, translateVectors[5]);
+
+        for (int i = 0; i < 6; ++i) {
+            emitHexagonVertex(center, translateVectors[i]);
+            emitHexagonVertex(rearCenter, translateVectors[i]);
+        }
+
+        EndPrimitive();
+    }
+
+    // Draw the main hexagon part.
+    normal = vec3(0.0, 0.0, 1.0);
+    emitHexagonVertex(center, translateVectors[5]);
+
+    for (int i = 0; i < 6; ++i) {
+        emitHexagonVertex(center, translateVectors[i]);
+        emitHexagonVertex(center, vec2(0.0, 0.0));
+    }
+
+    EndPrimitive();
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */