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91 lines
3.4 KiB
C++
91 lines
3.4 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry (AGG) - Version 2.5
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// A high quality rendering engine for C++
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// Copyright (C) 2002-2006 Maxim Shemanarev
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://antigrain.com
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//
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// AGG is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// AGG is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with AGG; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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// MA 02110-1301, USA.
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//----------------------------------------------------------------------------
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#include <math.h>
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#include "agg_line_aa_basics.h"
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namespace agg
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{
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//-------------------------------------------------------------------------
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// The number of the octant is determined as a 3-bit value as follows:
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// bit 0 = vertical flag
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// bit 1 = sx < 0
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// bit 2 = sy < 0
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//
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// [N] shows the number of the orthogonal quadrant
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// <M> shows the number of the diagonal quadrant
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// <1>
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// [1] | [0]
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// . (3)011 | 001(1) .
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// . | .
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// . | .
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// . | .
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// (2)010 .|. 000(0)
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// <2> ----------.+.----------- <0>
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// (6)110 . | . 100(4)
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// . | .
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// . | .
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// . | .
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// (7)111 | 101(5)
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// [2] | [3]
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// <3>
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// 0,1,2,3,4,5,6,7
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const int8u line_parameters::s_orthogonal_quadrant[8] = { 0,0,1,1,3,3,2,2 };
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const int8u line_parameters::s_diagonal_quadrant[8] = { 0,1,2,1,0,3,2,3 };
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//-------------------------------------------------------------------------
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void bisectrix(const line_parameters& l1,
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const line_parameters& l2,
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int* x, int* y)
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{
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double k = double(l2.len) / double(l1.len);
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double tx = l2.x2 - (l2.x1 - l1.x1) * k;
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double ty = l2.y2 - (l2.y1 - l1.y1) * k;
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//All bisectrices must be on the right of the line
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//If the next point is on the left (l1 => l2.2)
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//then the bisectix should be rotated by 180 degrees.
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if(double(l2.x2 - l2.x1) * double(l2.y1 - l1.y1) <
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double(l2.y2 - l2.y1) * double(l2.x1 - l1.x1) + 100.0)
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{
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tx -= (tx - l2.x1) * 2.0;
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ty -= (ty - l2.y1) * 2.0;
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}
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// Check if the bisectrix is too short
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double dx = tx - l2.x1;
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double dy = ty - l2.y1;
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if((int)sqrt(dx * dx + dy * dy) < line_subpixel_scale)
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{
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*x = (l2.x1 + l2.x1 + (l2.y1 - l1.y1) + (l2.y2 - l2.y1)) >> 1;
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*y = (l2.y1 + l2.y1 - (l2.x1 - l1.x1) - (l2.x2 - l2.x1)) >> 1;
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return;
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}
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*x = iround(tx);
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*y = iround(ty);
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}
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}
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