forked from Archive/PX4-Autopilot
172 lines
6.5 KiB
C
172 lines
6.5 KiB
C
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/****************************************************************************
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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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