/**************************************************************************** * graphics/nxglib/nxglib_circlepts.c * * Copyright (C) 2011 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include /**************************************************************************** * 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; }