56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/* geometry.c
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*
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* Created by Rory Healy (healyr@student.unimelb.edu.au)
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* Created on 9th September 2021
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* Last modified 9th September 2021
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*
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* A small library of functions used in the geometric construction of a
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* Voronoi diagram.
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*
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*/
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#ifndef GEOMETRY_HEADER
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#include "geometry.h"
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#endif
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#ifndef COMMON_HEADER
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#include "common.h"
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#endif
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bisector_t getBisector(vertex_t *pointA, vertex_t *pointB) {
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bisector_t newBisector;
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double midpointX = (pointA->x + pointB->x) / 2;
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double midpointY = (pointA->y + pointB->y) / 2;
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newBisector.x = midpointX;
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newBisector.y = midpointY;
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/* Calculating bisector slope according to slope of AB */
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if (pointA->x == pointB->x) {
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/* The line segment AB has an infinite gradient,
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* so the orthogonal line will have zero slope.
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*/
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newBisector.slope = 0;
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newBisector.isSlopeInfinite = 0;
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} else if (pointA->y == pointB->y) {
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/* The line segment AB has gradient of zero, so
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* the orthogonal line will have an infinite slope.
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*/
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newBisector.isSlopeInfinite = 1;
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/* Not actually zero, just a placeholder to prevent
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* accidental errors
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*/
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newBisector.slope = 0;
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} else {
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/* Slope of the line segment AB */
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double segmentSlope = \
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(pointB->y - pointA->y) / (pointB->x - pointA->x);
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/* Calculate orthogonal slope */
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newBisector.isSlopeInfinite = 0;
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newBisector.slope = -1 / segmentSlope;
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}
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return newBisector;
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}
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