1 files changed, 87 insertions, 0 deletions
diff --git a/vcl/opengl/shaders/areaHashCRC64TFragmentShader.glsl b/vcl/opengl/shaders/areaHashCRC64TFragmentShader.glsl
new file mode 100644
index 000000000000..901b481d8081
--- /dev/null
+++ b/vcl/opengl/shaders/areaHashCRC64TFragmentShader.glsl
@@ -0,0 +1,87 @@
+/* -*- 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/.
+ */
+
+/* TODO Use textureOffset for newest version of GLSL */
+
+
+#version 130
+
+uniform sampler2D crc_table;
+uniform sampler2D sampler;
+uniform float xstep;
+uniform float ystep;
+
+varying vec2 tex_coord;
+
+const int scale = 4;
+const float ratio = 16.0;
+
+
+ivec2 crc64( ivec2 hval, int color )
+{
+    int dx = 2 * ((hval[0] ^ color) & 0xff);
+    float s = dx / 255.0;
+    vec4 table_value_lo = round(texture2D( crc_table, vec2( s, 0.0 ) ) * 255.0);
+    s = (dx+1) / 255.0;
+    vec4 table_value_hi = round(texture2D( crc_table, vec2( s, 0.0 ) ) * 255.0);
+
+    int tvalue_lo = int(table_value_lo[0]) | (int(table_value_lo[1]) << 8) | (int(table_value_lo[2]) << 16) | (int(table_value_lo[3]) << 24);
+    int tvalue_hi = int(table_value_hi[0]) | (int(table_value_hi[1]) << 8) | (int(table_value_hi[2]) << 16) | (int(table_value_hi[3]) << 24);
+
+    hval[1] = tvalue_hi ^ (hval[1] >> 8);
+    hval[0] = tvalue_lo ^ ( (hval[1] << 24) | (hval[0] >> 8) );
+
+    return hval;
+}
+
+
+void main(void)
+{
+    ivec2 Crc = ivec2( 0xffffffff, 0xffffffff );
+    vec2 offset = vec2( 0.0, 0.0 );
+    vec2 next_coord = tex_coord.st;
+    for( int y = 0; y < scale && next_coord.y <= 1.0; ++y )
+    {
+        for( int x = 0; x < scale && next_coord.x <= 1.0; ++x )
+        {
+            vec4 pixel = round(texture2D( sampler, next_coord ) * 255.0);
+
+            int r = int(pixel.r); // 0..255
+            int g = int(pixel.g); // 0..255
+            int b = int(pixel.b); // 0..255
+            int a = int(pixel.a); // 0..255
+
+            Crc = crc64( Crc, r );
+            Crc = crc64( Crc, g );
+            Crc = crc64( Crc, b );
+            Crc = crc64( Crc, a );
+
+            offset.x += xstep;
+            next_coord = tex_coord.st + offset;
+        }
+        offset.y += ystep;
+        offset.x = 0.0;
+        next_coord = tex_coord.st + offset;
+    }
+
+    Crc[0] = ~Crc[0];
+    Crc[1] = ~Crc[1];
+
+    int Hash = Crc[0] ^ Crc[1];
+
+    float fr = ( Hash        & 0xff) / 255.0;
+    float fg = ((Hash >> 8)  & 0xff) / 255.0;
+    float fb = ((Hash >> 16) & 0xff) / 255.0;
+    float fa = ((Hash >> 24) & 0xff) / 255.0;
+
+
+     gl_FragColor = vec4(fr, fg, fb, fa);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */