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234 lines
7.7 KiB
C
234 lines
7.7 KiB
C
#pragma once
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/*
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** geometry.h
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** basic geometry math routines
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**
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**---------------------------------------------------------------------------
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** Copyright 2005-2022 Christoph Oelckers
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** All rights reserved.
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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 the
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** documentation and/or other materials provided with the distribution.
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** 3. The name of the author may not be used to endorse or promote products
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** derived from this software without specific prior written permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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**---------------------------------------------------------------------------
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*/
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#include "vectors.h"
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inline DVector2 rotatepoint(const DVector2& pivot, const DVector2& point, DAngle angle)
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{
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return (point - pivot).Rotated(angle) + pivot;
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}
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//==========================================================================
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//
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//
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//
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//==========================================================================
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inline double PointOnLineSide(double x, double y, double linex, double liney, double deltax, double deltay)
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{
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return (x - linex) * deltay - (y - liney) * deltax;
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}
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//==========================================================================
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//
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//
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//
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//==========================================================================
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inline double SquareDist(double lx1, double ly1, double lx2, double ly2)
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{
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double dx = lx2 - lx1;
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double dy = ly2 - ly1;
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return dx * dx + dy * dy;
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}
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// This is for cases where only the factor is needed, and pre-validation was performed.
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inline double NearestPointOnLineFast(double px, double py, double lx1, double ly1, double lx2, double ly2)
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{
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double wall_length = SquareDist(lx1, ly1, lx2, ly2);
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assert(wall_length > 0);
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return ((px - lx1) * (lx2 - lx1) + (py - ly1) * (ly2 - ly1)) / wall_length;
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}
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inline DVector2 NearestPointOnLine(double px, double py, double lx1, double ly1, double lx2, double ly2, bool clamp = true)
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{
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double wall_length = SquareDist(lx1, ly1, lx2, ly2);
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if (wall_length == 0)
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{
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return { lx1, ly1 };
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}
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double t = ((px - lx1) * (lx2 - lx1) + (py - ly1) * (ly2 - ly1)) / wall_length;
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if (clamp)
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{
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if (t <= 0) return { lx1, ly1 };
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if (t >= 1) return { lx2, ly2 };
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}
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double xx = lx1 + t * (lx2 - lx1);
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double yy = ly1 + t * (ly2 - ly1);
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return { xx, yy };
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}
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//==========================================================================
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//
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//
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//
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//==========================================================================
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inline double SquareDistToLine(double px, double py, double lx1, double ly1, double lx2, double ly2)
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{
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double wall_length = SquareDist(lx1, ly1, lx2, ly2);
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if (wall_length == 0) return SquareDist(px, py, lx1, ly1);
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double t = ((px - lx1) * (lx2 - lx1) + (py - ly1) * (ly2 - ly1)) / wall_length;
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t = clamp(t, 0., 1.);
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double xx = lx1 + t * (lx2 - lx1);
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double yy = ly1 + t * (ly2 - ly1);
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return SquareDist(px, py, xx, yy);
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}
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//==========================================================================
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//
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// taken from GZDoom with the divline_t parameters removed
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//
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//==========================================================================
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inline double InterceptVector(double v2x, double v2y, double v2dx, double v2dy, double v1x, double v1y, double v1dx, double v1dy)
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{
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double den = v1dy * v2dx - v1dx * v2dy;
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if (den == 0)
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return 0; // parallel
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double num = (v1x - v2x) * v1dy + (v2y - v1y) * v1dx;
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return num / den;
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}
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//==========================================================================
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//
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// Essentially two InterceptVector calls. We can reduce the calculations
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// because the denominators for both calculations only differ by their sign.
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//
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//==========================================================================
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inline double InterceptLineSegments(double v2x, double v2y, double v2dx, double v2dy, double v1x, double v1y, double v1dx, double v1dy, double* pfactor1 = nullptr, bool forcansee = false)
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{
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double den = v1dy * v2dx - v1dx * v2dy;
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if (den == 0)
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return -2 * (double)FLT_MAX; // parallel (return a magic value different from everything else, just in case it needs to be handled)
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if (forcansee && den < 0) // cansee does this added check here, aside from that its logic is virtually the same.
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return -1; // hitting the backside
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// perform the division first for better parallelization.
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den = 1 / den;
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double factor1 = ((v2x - v1x) * v2dy + (v1y - v2y) * v2dx) * -den;
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if (factor1 < 0 || factor1 >= 1) return -FLT_MAX; // no intersection
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if (pfactor1) *pfactor1 = factor1;
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return ((v1x - v2x) * v1dy + (v2y - v1y) * v1dx) * den; // this one's for the line segment where we want to get the intercept factor for so it needs to be last.
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}
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//==========================================================================
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//
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// calculates intersection between a plane and line in 3D
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//
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//==========================================================================
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inline double LinePlaneIntersect(const DVector3& start, const DVector3& trace, const DVector3& ppoint, const DVector3& pvec1, const DVector3& pvec2)
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{
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auto normal = pvec1 ^ pvec2; // we do not need a unit vector here.
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double dist = normal.dot(ppoint);
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double dotStart = normal.dot(start);
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double dotTrace = normal.dot(trace);
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if (dotTrace == 0) return -FLT_MAX;
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return (dist - dotStart) / dotTrace; // we are only interested in the factor
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}
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//==========================================================================
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//
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// BoxOnLineSide
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//
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// Based on Doom's, but rewritten to be standalone
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//
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//==========================================================================
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inline int BoxOnLineSide(const DVector2& boxtl, const DVector2& boxbr, const DVector2& start, const DVector2& delta)
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{
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int p1;
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int p2;
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if (delta.X == 0)
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{
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p1 = boxbr.X < start.X;
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p2 = boxtl.X < start.X;
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if (delta.Y < 0)
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{
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p1 ^= 1;
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p2 ^= 1;
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}
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}
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else if (delta.Y == 0)
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{
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p1 = boxtl.Y > start.Y;
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p2 = boxbr.Y > start.Y;
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if (delta.X < 0)
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{
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p1 ^= 1;
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p2 ^= 1;
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}
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}
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else if (delta.X * delta.Y <= 0)
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{
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p1 = PointOnLineSide(boxtl.X, boxtl.Y, start.X, start.Y, delta.X, delta.Y) > 0;
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p2 = PointOnLineSide(boxbr.X, boxbr.Y, start.X, start.Y, delta.X, delta.Y) > 0;
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}
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else
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{
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p1 = PointOnLineSide(boxbr.X, boxtl.Y, start.X, start.Y, delta.X, delta.Y) > 0;
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p2 = PointOnLineSide(boxtl.X, boxbr.Y, start.X, start.Y, delta.X, delta.Y) > 0;
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}
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return (p1 == p2) ? p1 : -1;
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}
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//==========================================================================
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//
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// BoxInRange
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//
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//==========================================================================
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inline bool BoxInRange(const DVector2& boxtl, const DVector2& boxbr, const DVector2& start, const DVector2& end)
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{
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return boxtl.X < max(start.X, end.X) &&
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boxbr.X > min(start.X, end.X) &&
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boxtl.Y < max(start.Y, end.Y) &&
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boxbr.Y > min(start.Y, end.Y);
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}
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