88 lines
2.5 KiB
Java
88 lines
2.5 KiB
Java
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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/* TODO Use textureOffset for newest version of GLSL */
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#version 130
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uniform sampler2D crc_table;
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uniform sampler2D sampler;
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uniform float xstep;
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uniform float ystep;
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varying vec2 tex_coord;
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const int scale = 4;
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const float ratio = 16.0;
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ivec2 crc64( ivec2 hval, int color )
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{
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int dx = 2 * ((hval[0] ^ color) & 0xff);
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float s = dx / 255.0;
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vec4 table_value_lo = round(texture2D( crc_table, vec2( s, 0.0 ) ) * 255.0);
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s = (dx+1) / 255.0;
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vec4 table_value_hi = round(texture2D( crc_table, vec2( s, 0.0 ) ) * 255.0);
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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);
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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);
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hval[1] = tvalue_hi ^ (hval[1] >> 8);
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hval[0] = tvalue_lo ^ ( (hval[1] << 24) | (hval[0] >> 8) );
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return hval;
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}
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void main(void)
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{
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ivec2 Crc = ivec2( 0xffffffff, 0xffffffff );
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vec2 offset = vec2( 0.0, 0.0 );
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vec2 next_coord = tex_coord.st;
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for( int y = 0; y < scale && next_coord.y <= 1.0; ++y )
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{
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for( int x = 0; x < scale && next_coord.x <= 1.0; ++x )
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{
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vec4 pixel = round(texture2D( sampler, next_coord ) * 255.0);
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int r = int(pixel.r); // 0..255
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int g = int(pixel.g); // 0..255
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int b = int(pixel.b); // 0..255
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int a = int(pixel.a); // 0..255
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Crc = crc64( Crc, r );
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Crc = crc64( Crc, g );
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Crc = crc64( Crc, b );
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Crc = crc64( Crc, a );
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offset.x += xstep;
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next_coord = tex_coord.st + offset;
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}
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offset.y += ystep;
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offset.x = 0.0;
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next_coord = tex_coord.st + offset;
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}
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Crc[0] = ~Crc[0];
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Crc[1] = ~Crc[1];
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int Hash = Crc[0] ^ Crc[1];
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float fr = ( Hash & 0xff) / 255.0;
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float fg = ((Hash >> 8) & 0xff) / 255.0;
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float fb = ((Hash >> 16) & 0xff) / 255.0;
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float fa = ((Hash >> 24) & 0xff) / 255.0;
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gl_FragColor = vec4(fr, fg, fb, fa);
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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