/****************************************************************************
* graphics/nxglib/nxglib_circlepts.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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) */
/* Named indices into the 16 circle points generated by nxgl_circlepts */
#define POINT_0p0 0
#define POINT_22p5 1
#define POINT_45p0 2
#define POINT_67p5 3
#define POINT_90p0 4
#define POINT_112p5 5
#define POINT_135p0 6
#define POINT_157p5 7
#define POINT_180p0 8
#define POINT_202p5 9
#define POINT_225p0 10
#define POINT_247p5 11
#define POINT_270p0 12
#define POINT_292p5 13
#define POINT_315p0 14
#define POINT_337p5 15
#define NCIRCLE_POINTS 16
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxgl_circlepts
*
* Description:
* Given a description of a circle, return a set of 16 points on the
* circumference of the circle. These points may then be used by
* nx_drawcircle() or related APIs to draw a circle outline.
*
* 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 16 points where the
* circle points will be returned.
*
* Returned value:
* None
*
****************************************************************************/
void nxgl_circlepts(FAR const struct nxgl_point_s *center, nxgl_coord_t radius,
FAR struct nxgl_point_s *circle)
{
nxgl_coord_t xoffs;
nxgl_coord_t yoffs;
/* 0, 90, 180, and 270 degrees are the easiest */
circle[POINT_0p0].x = center->x + radius;
circle[POINT_0p0].y = center->y;
circle[POINT_90p0].x = center->x;
circle[POINT_90p0].y = center->y + radius;
circle[POINT_180p0].x = center->x - radius;
circle[POINT_180p0].y = center->y;
circle[POINT_270p0].x = center->x;
circle[POINT_270p0].y = center->y - radius;
/* 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[POINT_22p5].x = center->x + xoffs;
circle[POINT_22p5].y = center->y + yoffs;
circle[POINT_157p5].x = center->x - xoffs;
circle[POINT_157p5].y = center->y + yoffs;
circle[POINT_202p5].x = center->x - xoffs;
circle[POINT_202p5].y = center->y - yoffs;
circle[POINT_337p5].x = center->x + xoffs;
circle[POINT_337p5].y = center->y - yoffs;
circle[POINT_67p5].x = center->x + yoffs;
circle[POINT_67p5].y = center->y + xoffs;
circle[POINT_112p5].x = center->x - yoffs;
circle[POINT_112p5].y = center->y + xoffs;
circle[POINT_247p5].x = center->x - yoffs;
circle[POINT_247p5].y = center->y - xoffs;
circle[POINT_292p5].x = center->x + yoffs;
circle[POINT_292p5].y = center->y - xoffs;
/* Finally, 45.0, 135.0, 225.0, 315.0 */
xoffs = b16toi(b16muli(COS_45p0, radius) + b16HALF);
circle[POINT_45p0].x = center->x + xoffs;
circle[POINT_45p0].y = center->y + xoffs;
circle[POINT_135p0].x = center->x - xoffs;
circle[POINT_135p0].y = center->y + xoffs;
circle[POINT_225p0].x = center->x - xoffs;
circle[POINT_225p0].y = center->y - xoffs;
circle[POINT_315p0].x = center->x + xoffs;
circle[POINT_315p0].y = center->y - xoffs;
}
