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105 lines
3.9 KiB
105 lines
3.9 KiB
/*
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u8g2_arc.c
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Universal 8bit Graphics Library (https://github.com/olikraus/u8g2/)
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Copyright (c) 2023, olikraus@gmail.com
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All rights reserved.
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Redistribution and use in source and binary forms, with or without modification,
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are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this list
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of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice, this
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list of conditions and the following disclaimer in the documentation and/or other
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materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "u8g2.h"
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static void u8g2_draw_arc(u8g2_t *u8g2, u8g2_uint_t x0, u8g2_uint_t y0, u8g2_uint_t rad, uint8_t start, uint8_t end)
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{
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// Manage angle inputs
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uint8_t full = (start == end);
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uint8_t inverted = (start > end);
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uint8_t a_start = inverted ? end : start;
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uint8_t a_end = inverted ? start : end;
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// Initialize variables
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uint32_t ratio;
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u8g2_int_t x = 0;
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u8g2_int_t y = rad;
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u8g2_int_t d = rad - 1;
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// Trace arc radius with the Andres circle algorithm (process each pixel of a 1/8th circle of radius rad)
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while (y >= x)
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{
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// Get the percentage of 1/8th circle drawn with a fast approximation of arctan(x/y)
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ratio = x * 255 / y; // x/y [0..255]
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ratio = ratio * (770195 - (ratio - 255) * (ratio + 941)) / 6137491; // arctan(x/y) [0..32]
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// Fill the pixels of the 8 sections of the circle, but only on the arc defined by the angles (start and end)
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if(full || ((ratio >= a_start && ratio < a_end) ^ inverted)) u8g2_DrawPixel(u8g2, x0 + y, y0 - x);
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if(full || (((ratio + a_end) > 63 && (ratio + a_start) <= 63) ^ inverted)) u8g2_DrawPixel(u8g2, x0 + x, y0 - y);
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if(full || (((ratio + 64) >= a_start && (ratio + 64) < a_end) ^ inverted)) u8g2_DrawPixel(u8g2, x0 - x, y0 - y);
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if(full || (((ratio + a_end) > 127 && (ratio + a_start) <= 127) ^ inverted)) u8g2_DrawPixel(u8g2, x0 - y, y0 - x);
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if(full || (((ratio + 128) >= a_start && (ratio + 128) < a_end) ^ inverted)) u8g2_DrawPixel(u8g2, x0 - y, y0 + x);
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if(full || (((ratio + a_end) > 191 && (ratio + a_start) <= 191) ^ inverted)) u8g2_DrawPixel(u8g2, x0 - x, y0 + y);
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if(full || (((ratio + 192) >= a_start && (ratio + 192) < a_end) ^ inverted)) u8g2_DrawPixel(u8g2, x0 + x, y0 + y);
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if(full || (((ratio + a_end) > 255 && (ratio + a_start) <= 255) ^ inverted)) u8g2_DrawPixel(u8g2, x0 + y, y0 + x);
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// Run Andres circle algorithm to get to the next pixel
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if (d >= 2 * x)
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{
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d = d - 2 * x - 1;
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x = x + 1;
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}
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else if (d < 2 * (rad - y))
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{
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d = d + 2 * y - 1;
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y = y - 1;
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}
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else
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{
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d = d + 2 * (y - x - 1);
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y = y - 1;
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x = x + 1;
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}
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}
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}
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void u8g2_DrawArc(u8g2_t *u8g2, u8g2_uint_t x0, u8g2_uint_t y0, u8g2_uint_t rad, uint8_t start, uint8_t end)
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{
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/* check for bounding box */
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#ifdef U8G2_WITH_INTERSECTION
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{
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if ( u8g2_IsIntersection(u8g2, x0-rad, y0-rad, x0+rad+1, y0+rad+1) == 0 )
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return;
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}
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#endif /* U8G2_WITH_INTERSECTION */
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/* draw arc */
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u8g2_draw_arc(u8g2, x0, y0, rad, start, end);
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}
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