177 lines
6.7 KiB
C
177 lines
6.7 KiB
C
/****************************************************************************
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* graphics/nxglib/nxglib_circletraps.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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/****************************************************************************
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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_circletraps
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*
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* Description:
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* Given a description of a a circle, return 8 trapezoids that can be
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* used to fill the circle by nx_fillcircle() and other interfaces.
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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 8 trapezoids where
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* the circle description 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_circletraps(FAR const struct nxgl_point_s *center, nxgl_coord_t radius,
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FAR struct nxgl_trapezoid_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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circle[0].top.x1 = itob16(center->x);
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circle[0].top.x2 = circle[0].top.x1;
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circle[0].top.y = center->y - radius;
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circle[7].bot.x1 = circle[0].top.x1;
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circle[7].bot.x2 = circle[0].top.x1;
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circle[7].bot.y = center->y + radius;
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circle[3].bot.x1 = itob16(center->x - radius);
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circle[3].bot.x2 = itob16(center->x + radius);
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circle[3].bot.y = center->y;
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circle[4].top.x1 = circle[3].bot.x1;
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circle[4].top.x2 = circle[3].bot.x2;
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circle[4].top.y = circle[3].bot.y;
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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[2].bot.x1 = itob16(center->x - xoffs);
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circle[2].bot.x2 = itob16(center->x + xoffs);
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circle[2].bot.y = center->y - yoffs;
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circle[3].top.x1 = circle[2].bot.x1;
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circle[3].top.x2 = circle[2].bot.x2;
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circle[3].top.y = circle[2].bot.y;
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circle[4].bot.x1 = circle[2].bot.x1;
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circle[4].bot.x2 = circle[2].bot.x2;
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circle[4].bot.y = center->y + yoffs;
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circle[5].top.x1 = circle[4].bot.x1;
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circle[5].top.x2 = circle[4].bot.x2;
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circle[5].top.y = circle[4].bot.y;
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circle[0].bot.x1 = itob16(center->x - yoffs);
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circle[0].bot.x2 = itob16(center->x + yoffs);
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circle[0].bot.y = center->y - xoffs;
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circle[1].top.x1 = circle[0].bot.x1;
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circle[1].top.x2 = circle[0].bot.x2;
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circle[1].top.y = circle[0].bot.y;
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circle[6].bot.x1 = circle[1].top.x1;
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circle[6].bot.x2 = circle[1].top.x2;
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circle[6].bot.y = center->y + xoffs;
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circle[7].top.x1 = circle[6].bot.x1;
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circle[7].top.x2 = circle[6].bot.x2;
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circle[7].top.y = circle[6].bot.y;
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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[1].bot.x1 = itob16(center->x - xoffs);
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circle[1].bot.x2 = itob16(center->x + xoffs);
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circle[1].bot.y = center->y - xoffs;
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circle[2].top.x1 = circle[1].bot.x1;
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circle[2].top.x2 = circle[1].bot.x2;
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circle[2].top.y = circle[1].bot.y;
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circle[5].bot.x1 = circle[1].bot.x1;
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circle[5].bot.x2 = circle[1].bot.x2;
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circle[5].bot.y = center->y + xoffs;
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circle[6].top.x1 = circle[5].bot.x1;
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circle[6].top.x2 = circle[5].bot.x2;
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circle[6].top.y = circle[5].bot.y;
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}
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