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171 lines
6.5 KiB
171 lines
6.5 KiB
/**************************************************************************** |
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* graphics/nxglib/nxglib_circlepts.c |
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* |
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* Copyright (C) 2011 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <string.h> |
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#include <errno.h> |
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#include <fixedmath.h> |
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#include <nuttx/nx/nxglib.h> |
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/**************************************************************************** |
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* Pre-Processor Definitions |
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****************************************************************************/ |
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/* Trigonometry */ |
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#define SIN_0p0 0 /* sin(0) = 0 */ |
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#define COS_0p0 1 /* cos(0) = 1 */ |
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#define SIN_22p5 25080 /* sin(22.5) = 25080 / 65536 */ |
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#define COS_22p5 60547 /* cos(22.5) = 60547 / 65536 */ |
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#define SIN_45p0 46341 /* sin(45) = 46341 / 65536 */ |
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#define COS_45p0 SIN_45p0 /* cos(45) = sin(45) */ |
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/* Named indices into the 16 circle points generated by nxgl_circlepts */ |
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#define POINT_0p0 0 |
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#define POINT_22p5 1 |
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#define POINT_45p0 2 |
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#define POINT_67p5 3 |
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#define POINT_90p0 4 |
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#define POINT_112p5 5 |
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#define POINT_135p0 6 |
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#define POINT_157p5 7 |
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#define POINT_180p0 8 |
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#define POINT_202p5 9 |
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#define POINT_225p0 10 |
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#define POINT_247p5 11 |
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#define POINT_270p0 12 |
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#define POINT_292p5 13 |
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#define POINT_315p0 14 |
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#define POINT_337p5 15 |
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#define NCIRCLE_POINTS 16 |
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/**************************************************************************** |
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* Private Types |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Name: nxgl_circlepts |
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* |
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* Description: |
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* Given a description of a circle, return a set of 16 points on the |
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* circumference of the circle. These points may then be used by |
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* nx_drawcircle() or related APIs to draw a circle outline. |
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* |
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* Input parameters: |
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* center - A pointer to the point that is the center of the circle |
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* radius - The radius of the circle in pixels. |
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* circle - A pointer the first entry in an array of 16 points where the |
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* circle points will be returned. |
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* |
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* Returned value: |
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* None |
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* |
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****************************************************************************/ |
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void nxgl_circlepts(FAR const struct nxgl_point_s *center, nxgl_coord_t radius, |
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FAR struct nxgl_point_s *circle) |
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{ |
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nxgl_coord_t xoffs; |
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nxgl_coord_t yoffs; |
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/* 0, 90, 180, and 270 degrees are the easiest */ |
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circle[POINT_0p0].x = center->x + radius; |
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circle[POINT_0p0].y = center->y; |
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circle[POINT_90p0].x = center->x; |
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circle[POINT_90p0].y = center->y + radius; |
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circle[POINT_180p0].x = center->x - radius; |
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circle[POINT_180p0].y = center->y; |
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circle[POINT_270p0].x = center->x; |
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circle[POINT_270p0].y = center->y - radius; |
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/* Now 22.5, 67.5, 112.5, 157.5, 202.5, 247.5, 292.5, and 337.5 */ |
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xoffs = b16toi(b16muli(COS_22p5, radius) + b16HALF); |
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yoffs = b16toi(b16muli(SIN_22p5, radius) + b16HALF); |
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circle[POINT_22p5].x = center->x + xoffs; |
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circle[POINT_22p5].y = center->y + yoffs; |
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circle[POINT_157p5].x = center->x - xoffs; |
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circle[POINT_157p5].y = center->y + yoffs; |
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circle[POINT_202p5].x = center->x - xoffs; |
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circle[POINT_202p5].y = center->y - yoffs; |
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circle[POINT_337p5].x = center->x + xoffs; |
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circle[POINT_337p5].y = center->y - yoffs; |
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circle[POINT_67p5].x = center->x + yoffs; |
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circle[POINT_67p5].y = center->y + xoffs; |
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circle[POINT_112p5].x = center->x - yoffs; |
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circle[POINT_112p5].y = center->y + xoffs; |
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circle[POINT_247p5].x = center->x - yoffs; |
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circle[POINT_247p5].y = center->y - xoffs; |
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circle[POINT_292p5].x = center->x + yoffs; |
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circle[POINT_292p5].y = center->y - xoffs; |
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/* Finally, 45.0, 135.0, 225.0, 315.0 */ |
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xoffs = b16toi(b16muli(COS_45p0, radius) + b16HALF); |
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circle[POINT_45p0].x = center->x + xoffs; |
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circle[POINT_45p0].y = center->y + xoffs; |
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circle[POINT_135p0].x = center->x - xoffs; |
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circle[POINT_135p0].y = center->y + xoffs; |
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circle[POINT_225p0].x = center->x - xoffs; |
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circle[POINT_225p0].y = center->y - xoffs; |
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circle[POINT_315p0].x = center->x + xoffs; |
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circle[POINT_315p0].y = center->y - xoffs; |
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}
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