342 lines
7.8 KiB
C
342 lines
7.8 KiB
C
/*
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* libcaca Colour ASCII-Art library
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* Copyright © 2002—2018 Sam Hocevar <sam@hocevar.net>
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* All Rights Reserved
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*
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* This library is free software. It comes without any warranty, to
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* the extent permitted by applicable law. You can redistribute it
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* and/or modify it under the terms of the Do What the Fuck You Want
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* to Public License, Version 2, as published by Sam Hocevar. See
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* http://www.wtfpl.net/ for more details.
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*/
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/*
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* This file contains ellipse and circle drawing functions, both filled
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* and outline.
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*/
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#include "config.h"
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#if !defined(__KERNEL__)
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# include <stdlib.h>
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#endif
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#include "caca.h"
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#include "caca_internals.h"
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static void ellipsepoints(caca_canvas_t *, int, int, int, int, uint32_t, int);
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/** \brief Draw a circle on the canvas using the given character.
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*
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* This function never fails.
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*
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* \param cv The handle to the libcaca canvas.
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* \param x Center X coordinate.
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* \param y Center Y coordinate.
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* \param r Circle radius.
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* \param ch UTF-32 character to be used to draw the circle outline.
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* \return This function always returns 0.
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*/
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int caca_draw_circle(caca_canvas_t *cv, int x, int y, int r, uint32_t ch)
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{
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int test, dx, dy;
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/* Optimized Bresenham. Kick ass. */
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for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++)
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{
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ellipsepoints(cv, x, y, dx, dy, ch, 1);
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ellipsepoints(cv, x, y, dy, dx, ch, 1);
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test += test > 0 ? dx - dy-- : dx;
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}
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return 0;
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}
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/** \brief Fill an ellipse on the canvas using the given character.
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*
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* This function never fails.
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*
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* \param cv The handle to the libcaca canvas.
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* \param xo Center X coordinate.
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* \param yo Center Y coordinate.
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* \param a Ellipse X radius.
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* \param b Ellipse Y radius.
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* \param ch UTF-32 character to be used to fill the ellipse.
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* \return This function always returns 0.
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*/
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int caca_fill_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b,
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uint32_t ch)
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{
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int d2;
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int x = 0;
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int y = b;
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int d1 = b*b - (a*a*b) + (a*a/4);
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while(a*a*y - a*a/2 > b*b*(x+1))
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{
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if(d1 < 0)
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{
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d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
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}
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else
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{
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d1 += b*b*(2*x*1) + a*a*(-2*y+2);
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caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
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caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
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y--;
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}
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x++;
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}
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caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
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caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
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d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
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while(y > 0)
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{
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if(d2 < 0)
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{
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d2 += b*b*(2*x+2) + a*a*(-2*y+3);
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x++;
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}
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else
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{
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d2 += a*a*(-2*y+3);
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}
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y--;
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caca_draw_line(cv, xo - x, yo - y, xo + x, yo - y, ch);
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caca_draw_line(cv, xo - x, yo + y, xo + x, yo + y, ch);
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}
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return 0;
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}
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/** \brief Draw an ellipse on the canvas using the given character.
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*
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* This function never fails.
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*
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* \param cv The handle to the libcaca canvas.
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* \param xo Center X coordinate.
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* \param yo Center Y coordinate.
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* \param a Ellipse X radius.
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* \param b Ellipse Y radius.
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* \param ch UTF-32 character to be used to draw the ellipse outline.
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* \return This function always returns 0.
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*/
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int caca_draw_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b,
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uint32_t ch)
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{
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int d2;
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int x = 0;
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int y = b;
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int d1 = b*b - (a*a*b) + (a*a/4);
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ellipsepoints(cv, xo, yo, x, y, ch, 0);
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while(a*a*y - a*a/2 > b*b*(x+1))
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{
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if(d1 < 0)
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{
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d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
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}
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else
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{
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d1 += b*b*(2*x*1) + a*a*(-2*y+2);
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y--;
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}
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x++;
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ellipsepoints(cv, xo, yo, x, y, ch, 0);
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}
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d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
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while(y > 0)
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{
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if(d2 < 0)
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{
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d2 += b*b*(2*x+2) + a*a*(-2*y+3);
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x++;
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}
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else
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{
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d2 += a*a*(-2*y+3);
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}
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y--;
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ellipsepoints(cv, xo, yo, x, y, ch, 0);
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}
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return 0;
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}
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/** \brief Draw a thin ellipse on the canvas.
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*
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* This function never fails.
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*
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* \param cv The handle to the libcaca canvas.
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* \param xo Center X coordinate.
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* \param yo Center Y coordinate.
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* \param a Ellipse X radius.
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* \param b Ellipse Y radius.
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* \return This function always returns 0.
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*/
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int caca_draw_thin_ellipse(caca_canvas_t *cv, int xo, int yo, int a, int b)
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{
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/* FIXME: this is not correct */
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int d2;
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int x = 0;
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int y = b;
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int d1 = b*b - (a*a*b) + (a*a/4);
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ellipsepoints(cv, xo, yo, x, y, '-', 1);
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while(a*a*y - a*a/2 > b*b*(x+1))
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{
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if(d1 < 0)
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{
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d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
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ellipsepoints(cv, xo, yo, x + 1, y, '0', 1);
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}
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else
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{
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d1 += b*b*(2*x*1) + a*a*(-2*y+2);
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y--;
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ellipsepoints(cv, xo, yo, x + 1, y, '1', 1);
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}
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x++;
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}
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d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
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while(y > 0)
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{
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if(d2 < 0)
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{
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d2 += b*b*(2*x+2) + a*a*(-2*y+3);
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x++;
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ellipsepoints(cv, xo, yo, x , y - 1, '2', 1);
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}
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else
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{
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d2 += a*a*(-2*y+3);
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ellipsepoints(cv, xo, yo, x , y - 1, '3', 1);
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}
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y--;
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}
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return 0;
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}
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static void ellipsepoints(caca_canvas_t *cv, int xo, int yo, int x, int y,
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uint32_t ch, int thin)
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{
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uint8_t b = 0;
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if(xo + x >= 0 && xo + x < (int)cv->width)
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b |= 0x1;
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if(xo - x >= 0 && xo - x < (int)cv->width)
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b |= 0x2;
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if(yo + y >= 0 && yo + y < (int)cv->height)
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b |= 0x4;
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if(yo - y >= 0 && yo - y < (int)cv->height)
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b |= 0x8;
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if((b & (0x1|0x4)) == (0x1|0x4)) {
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uint32_t c = ch;
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if(thin) {
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switch(c) {
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case '0':
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c = '-';
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break;
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case '1':
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c = ',';
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break;
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case '2':
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c = '/';
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break;
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case '3':
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c = '|';
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break;
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}
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}
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caca_put_char(cv, xo + x, yo + y, c);
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}
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if((b & (0x2|0x4)) == (0x2|0x4)) {
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uint32_t c = ch;
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if(thin) {
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switch(c) {
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case '0':
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c = '-';
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break;
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case '1':
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c = '.';
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break;
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case '2':
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c = '\\';
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break;
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case '3':
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c = '|';
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break;
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}
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}
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caca_put_char(cv, xo - x, yo + y, c);
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}
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if((b & (0x1|0x8)) == (0x1|0x8)) {
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uint32_t c = ch;
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if(thin) {
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switch(c) {
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case '0':
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c = '-';
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break;
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case '1':
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c = '`';
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break;
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case '2':
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c = '\\';
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break;
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case '3':
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c = '|';
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break;
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}
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}
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caca_put_char(cv, xo + x, yo - y, c);
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}
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if((b & (0x2|0x8)) == (0x2|0x8)) {
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uint32_t c = ch;
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if(thin) {
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switch(c) {
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case '0':
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c = '-';
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break;
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case '1':
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c = '\'';
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break;
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case '2':
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c = '/';
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break;
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case '3':
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c = '|';
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break;
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}
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}
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caca_put_char(cv, xo - x, yo - y, c);
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}
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}
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