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px4-firmware/nuttx/graphics/nxglib/nxglib_circletraps.c

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/****************************************************************************
* graphics/nxglib/nxglib_circletraps.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <string.h>
#include <errno.h>
#include <fixedmath.h>
#include <nuttx/nx/nxglib.h>
/****************************************************************************
* Pre-Processor Definitions
****************************************************************************/
/* Trigonometry */
#define SIN_0p0 0 /* sin(0) = 0 */
#define COS_0p0 1 /* cos(0) = 1 */
#define SIN_22p5 25080 /* sin(22.5) = 25080 / 65536 */
#define COS_22p5 60547 /* cos(22.5) = 60547 / 65536 */
#define SIN_45p0 46341 /* sin(45) = 46341 / 65536 */
#define COS_45p0 SIN_45p0 /* cos(45) = sin(45) */
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxgl_circletraps
*
* Description:
* Given a description of a a circle, return 8 trapezoids that can be
* used to fill the circle by nx_fillcircle() and other interfaces.
*
* Input parameters:
* center - A pointer to the point that is the center of the circle
* radius - The radius of the circle in pixels.
* circle - A pointer the first entry in an array of 8 trapezoids where
* the circle description will be returned.
*
* Returned value:
* None
*
****************************************************************************/
void nxgl_circletraps(FAR const struct nxgl_point_s *center, nxgl_coord_t radius,
FAR struct nxgl_trapezoid_s *circle)
{
nxgl_coord_t xoffs;
nxgl_coord_t yoffs;
circle[0].top.x1 = itob16(center->x);
circle[0].top.x2 = circle[0].top.x1;
circle[0].top.y = center->y - radius;
circle[7].bot.x1 = circle[0].top.x1;
circle[7].bot.x2 = circle[0].top.x1;
circle[7].bot.y = center->y + radius;
circle[3].bot.x1 = itob16(center->x - radius);
circle[3].bot.x2 = itob16(center->x + radius);
circle[3].bot.y = center->y;
circle[4].top.x1 = circle[3].bot.x1;
circle[4].top.x2 = circle[3].bot.x2;
circle[4].top.y = circle[3].bot.y;
/* Now 22.5, 67.5, 112.5, 157.5, 202.5, 247.5, 292.5, and 337.5 */
xoffs = b16toi(b16muli(COS_22p5, radius) + b16HALF);
yoffs = b16toi(b16muli(SIN_22p5, radius) + b16HALF);
circle[2].bot.x1 = itob16(center->x - xoffs);
circle[2].bot.x2 = itob16(center->x + xoffs);
circle[2].bot.y = center->y - yoffs;
circle[3].top.x1 = circle[2].bot.x1;
circle[3].top.x2 = circle[2].bot.x2;
circle[3].top.y = circle[2].bot.y;
circle[4].bot.x1 = circle[2].bot.x1;
circle[4].bot.x2 = circle[2].bot.x2;
circle[4].bot.y = center->y + yoffs;
circle[5].top.x1 = circle[4].bot.x1;
circle[5].top.x2 = circle[4].bot.x2;
circle[5].top.y = circle[4].bot.y;
circle[0].bot.x1 = itob16(center->x - yoffs);
circle[0].bot.x2 = itob16(center->x + yoffs);
circle[0].bot.y = center->y - xoffs;
circle[1].top.x1 = circle[0].bot.x1;
circle[1].top.x2 = circle[0].bot.x2;
circle[1].top.y = circle[0].bot.y;
circle[6].bot.x1 = circle[1].top.x1;
circle[6].bot.x2 = circle[1].top.x2;
circle[6].bot.y = center->y + xoffs;
circle[7].top.x1 = circle[6].bot.x1;
circle[7].top.x2 = circle[6].bot.x2;
circle[7].top.y = circle[6].bot.y;
/* Finally, 45.0, 135.0, 225.0, 315.0 */
xoffs = b16toi(b16muli(COS_45p0, radius) + b16HALF);
circle[1].bot.x1 = itob16(center->x - xoffs);
circle[1].bot.x2 = itob16(center->x + xoffs);
circle[1].bot.y = center->y - xoffs;
circle[2].top.x1 = circle[1].bot.x1;
circle[2].top.x2 = circle[1].bot.x2;
circle[2].top.y = circle[1].bot.y;
circle[5].bot.x1 = circle[1].bot.x1;
circle[5].bot.x2 = circle[1].bot.x2;
circle[5].bot.y = center->y + xoffs;
circle[6].top.x1 = circle[5].bot.x1;
circle[6].top.x2 = circle[5].bot.x2;
circle[6].top.y = circle[5].bot.y;
}
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