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- /*
- * libcucul Canvas for ultrafast compositing of Unicode letters
- * Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org>
- * All Rights Reserved
- *
- * $Id$
- *
- * This library is free software. It comes without any warranty, to
- * the extent permitted by applicable law. You can redistribute it
- * and/or modify it under the terms of the Do What The Fuck You Want
- * To Public License, Version 2, as published by Sam Hocevar. See
- * http://sam.zoy.org/wtfpl/COPYING for more details.
- */
-
- /*
- * This file contains triangle drawing functions, both filled and outline.
- */
-
- #include "config.h"
-
- #if !defined(__KERNEL__)
- # include <stdlib.h>
- #endif
-
- #include "cucul.h"
- #include "cucul_internals.h"
-
- /** \brief Draw a triangle on the canvas using the given character.
- *
- * This function never fails.
- *
- * \param cv The handle to the libcucul canvas.
- * \param x1 X coordinate of the first point.
- * \param y1 Y coordinate of the first point.
- * \param x2 X coordinate of the second point.
- * \param y2 Y coordinate of the second point.
- * \param x3 X coordinate of the third point.
- * \param y3 Y coordinate of the third point.
- * \param ch UTF-32 character to be used to draw the triangle outline.
- * \return This function always returns 0.
- */
- int cucul_draw_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
- int x3, int y3, uint32_t ch)
- {
- cucul_draw_line(cv, x1, y1, x2, y2, ch);
- cucul_draw_line(cv, x2, y2, x3, y3, ch);
- cucul_draw_line(cv, x3, y3, x1, y1, ch);
-
- return 0;
- }
-
- /** \brief Draw a thin triangle on the canvas.
- *
- * This function never fails.
- *
- * \param cv The handle to the libcucul canvas.
- * \param x1 X coordinate of the first point.
- * \param y1 Y coordinate of the first point.
- * \param x2 X coordinate of the second point.
- * \param y2 Y coordinate of the second point.
- * \param x3 X coordinate of the third point.
- * \param y3 Y coordinate of the third point.
- * \return This function always returns 0.
- */
- int cucul_draw_thin_triangle(cucul_canvas_t *cv, int x1, int y1,
- int x2, int y2, int x3, int y3)
- {
- cucul_draw_thin_line(cv, x1, y1, x2, y2);
- cucul_draw_thin_line(cv, x2, y2, x3, y3);
- cucul_draw_thin_line(cv, x3, y3, x1, y1);
-
- return 0;
- }
-
- /** \brief Fill a triangle on the canvas using the given character.
- *
- * This function never fails.
- *
- * \param cv The handle to the libcucul canvas.
- * \param x1 X coordinate of the first point.
- * \param y1 Y coordinate of the first point.
- * \param x2 X coordinate of the second point.
- * \param y2 Y coordinate of the second point.
- * \param x3 X coordinate of the third point.
- * \param y3 Y coordinate of the third point.
- * \param ch UTF-32 character to be used to fill the triangle.
- * \return This function always returns 0.
- */
- int cucul_fill_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
- int x3, int y3, uint32_t ch)
- {
- int x, y, xmin, xmax, ymin, ymax;
- long int xx1, xx2, xa, xb, sl21, sl31, sl32;
-
- /* Bubble-sort y1 <= y2 <= y3 */
- if(y1 > y2)
- return cucul_fill_triangle(cv, x2, y2, x1, y1, x3, y3, ch);
-
- if(y2 > y3)
- return cucul_fill_triangle(cv, x1, y1, x3, y3, x2, y2, ch);
-
- /* Compute slopes and promote precision */
- sl21 = (y2 == y1) ? 0 : (x2 - x1) * 0x10000 / (y2 - y1);
- sl31 = (y3 == y1) ? 0 : (x3 - x1) * 0x10000 / (y3 - y1);
- sl32 = (y3 == y2) ? 0 : (x3 - x2) * 0x10000 / (y3 - y2);
-
- x1 *= 0x10000;
- x2 *= 0x10000;
- x3 *= 0x10000;
-
- ymin = y1 < 0 ? 0 : y1;
- ymax = y3 + 1 < (int)cv->height ? y3 + 1 : (int)cv->height;
-
- if(ymin < y2)
- {
- xa = x1 + sl21 * (ymin - y1);
- xb = x1 + sl31 * (ymin - y1);
- }
- else if(ymin == y2)
- {
- xa = x2;
- xb = (y1 == y3) ? x3 : x1 + sl31 * (ymin - y1);
- }
- else /* (ymin > y2) */
- {
- xa = x3 + sl32 * (ymin - y3);
- xb = x3 + sl31 * (ymin - y3);
- }
-
- /* Rasterize our triangle */
- for(y = ymin; y < ymax; y++)
- {
- /* Rescale xa and xb, recentering the division */
- if(xa < xb)
- {
- xx1 = (xa + 0x800) / 0x10000;
- xx2 = (xb + 0x801) / 0x10000;
- }
- else
- {
- xx1 = (xb + 0x800) / 0x10000;
- xx2 = (xa + 0x801) / 0x10000;
- }
-
- xmin = xx1 < 0 ? 0 : xx1;
- xmax = xx2 + 1 < (int)cv->width ? xx2 + 1 : (int)cv->width;
-
- for(x = xmin; x < xmax; x++)
- cucul_put_char(cv, x, y, ch);
-
- xa += y < y2 ? sl21 : sl32;
- xb += sl31;
- }
-
- return 0;
- }
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