230 lines
8 KiB
C++
230 lines
8 KiB
C++
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/*
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Open Asset Import Library (assimp)
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----------------------------------------------------------------------
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Copyright (c) 2006-2019, assimp team
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All rights reserved.
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Redistribution and use of this software in source and binary forms,
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with or without modification, are permitted provided that the
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following conditions are met:
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* Redistributions of source code must retain the above
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copyright notice, this list of conditions and the
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following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other
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materials provided with the distribution.
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* Neither the name of the assimp team, nor the names of its
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contributors may be used to endorse or promote products
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derived from this software without specific prior
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written permission of the assimp team.
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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 FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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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
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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----------------------------------------------------------------------
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*/
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/** @file PolyTools.h, various utilities for our dealings with arbitrary polygons */
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#ifndef AI_POLYTOOLS_H_INCLUDED
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#define AI_POLYTOOLS_H_INCLUDED
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#include <assimp/material.h>
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#include <assimp/ai_assert.h>
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namespace Assimp {
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// -------------------------------------------------------------------------------
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/** Compute the signed area of a triangle.
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* The function accepts an unconstrained template parameter for use with
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* both aiVector3D and aiVector2D, but generally ignores the third coordinate.*/
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template <typename T>
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inline double GetArea2D(const T& v1, const T& v2, const T& v3)
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{
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return 0.5 * (v1.x * ((double)v3.y - v2.y) + v2.x * ((double)v1.y - v3.y) + v3.x * ((double)v2.y - v1.y));
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}
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// -------------------------------------------------------------------------------
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/** Test if a given point p2 is on the left side of the line formed by p0-p1.
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* The function accepts an unconstrained template parameter for use with
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* both aiVector3D and aiVector2D, but generally ignores the third coordinate.*/
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template <typename T>
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inline bool OnLeftSideOfLine2D(const T& p0, const T& p1,const T& p2)
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{
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return GetArea2D(p0,p2,p1) > 0;
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}
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// -------------------------------------------------------------------------------
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/** Test if a given point is inside a given triangle in R2.
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* The function accepts an unconstrained template parameter for use with
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* both aiVector3D and aiVector2D, but generally ignores the third coordinate.*/
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template <typename T>
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inline bool PointInTriangle2D(const T& p0, const T& p1,const T& p2, const T& pp)
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{
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// Point in triangle test using baryzentric coordinates
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const aiVector2D v0 = p1 - p0;
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const aiVector2D v1 = p2 - p0;
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const aiVector2D v2 = pp - p0;
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double dot00 = v0 * v0;
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double dot01 = v0 * v1;
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double dot02 = v0 * v2;
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double dot11 = v1 * v1;
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double dot12 = v1 * v2;
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const double invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
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dot11 = (dot11 * dot02 - dot01 * dot12) * invDenom;
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dot00 = (dot00 * dot12 - dot01 * dot02) * invDenom;
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return (dot11 > 0) && (dot00 > 0) && (dot11 + dot00 < 1);
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}
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// -------------------------------------------------------------------------------
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/** Check whether the winding order of a given polygon is counter-clockwise.
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* The function accepts an unconstrained template parameter, but is intended
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* to be used only with aiVector2D and aiVector3D (z axis is ignored, only
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* x and y are taken into account).
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* @note Code taken from http://cgm.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian/applet1.html and translated to C++
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*/
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template <typename T>
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inline bool IsCCW(T* in, size_t npoints) {
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double aa, bb, cc, b, c, theta;
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double convex_turn;
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double convex_sum = 0;
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ai_assert(npoints >= 3);
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for (size_t i = 0; i < npoints - 2; i++) {
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aa = ((in[i+2].x - in[i].x) * (in[i+2].x - in[i].x)) +
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((-in[i+2].y + in[i].y) * (-in[i+2].y + in[i].y));
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bb = ((in[i+1].x - in[i].x) * (in[i+1].x - in[i].x)) +
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((-in[i+1].y + in[i].y) * (-in[i+1].y + in[i].y));
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cc = ((in[i+2].x - in[i+1].x) *
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(in[i+2].x - in[i+1].x)) +
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((-in[i+2].y + in[i+1].y) *
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(-in[i+2].y + in[i+1].y));
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b = std::sqrt(bb);
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c = std::sqrt(cc);
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theta = std::acos((bb + cc - aa) / (2 * b * c));
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if (OnLeftSideOfLine2D(in[i],in[i+2],in[i+1])) {
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// if (convex(in[i].x, in[i].y,
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// in[i+1].x, in[i+1].y,
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// in[i+2].x, in[i+2].y)) {
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convex_turn = AI_MATH_PI_F - theta;
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convex_sum += convex_turn;
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}
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else {
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convex_sum -= AI_MATH_PI_F - theta;
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}
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}
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aa = ((in[1].x - in[npoints-2].x) *
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(in[1].x - in[npoints-2].x)) +
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((-in[1].y + in[npoints-2].y) *
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(-in[1].y + in[npoints-2].y));
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bb = ((in[0].x - in[npoints-2].x) *
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(in[0].x - in[npoints-2].x)) +
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((-in[0].y + in[npoints-2].y) *
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(-in[0].y + in[npoints-2].y));
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cc = ((in[1].x - in[0].x) * (in[1].x - in[0].x)) +
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((-in[1].y + in[0].y) * (-in[1].y + in[0].y));
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b = std::sqrt(bb);
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c = std::sqrt(cc);
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theta = std::acos((bb + cc - aa) / (2 * b * c));
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//if (convex(in[npoints-2].x, in[npoints-2].y,
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// in[0].x, in[0].y,
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// in[1].x, in[1].y)) {
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if (OnLeftSideOfLine2D(in[npoints-2],in[1],in[0])) {
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convex_turn = AI_MATH_PI_F - theta;
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convex_sum += convex_turn;
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}
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else {
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convex_sum -= AI_MATH_PI_F - theta;
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}
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return convex_sum >= (2 * AI_MATH_PI_F);
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}
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// -------------------------------------------------------------------------------
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/** Compute the normal of an arbitrary polygon in R3.
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*
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* The code is based on Newell's formula, that is a polygons normal is the ratio
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* of its area when projected onto the three coordinate axes.
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*
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* @param out Receives the output normal
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* @param num Number of input vertices
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* @param x X data source. x[ofs_x*n] is the n'th element.
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* @param y Y data source. y[ofs_y*n] is the y'th element
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* @param z Z data source. z[ofs_z*n] is the z'th element
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*
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* @note The data arrays must have storage for at least num+2 elements. Using
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* this method is much faster than the 'other' NewellNormal()
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*/
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template <int ofs_x, int ofs_y, int ofs_z, typename TReal>
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inline void NewellNormal (aiVector3t<TReal>& out, int num, TReal* x, TReal* y, TReal* z)
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{
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// Duplicate the first two vertices at the end
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x[(num+0)*ofs_x] = x[0];
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x[(num+1)*ofs_x] = x[ofs_x];
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y[(num+0)*ofs_y] = y[0];
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y[(num+1)*ofs_y] = y[ofs_y];
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z[(num+0)*ofs_z] = z[0];
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z[(num+1)*ofs_z] = z[ofs_z];
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TReal sum_xy = 0.0, sum_yz = 0.0, sum_zx = 0.0;
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TReal *xptr = x +ofs_x, *xlow = x, *xhigh = x + ofs_x*2;
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TReal *yptr = y +ofs_y, *ylow = y, *yhigh = y + ofs_y*2;
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TReal *zptr = z +ofs_z, *zlow = z, *zhigh = z + ofs_z*2;
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for (int tmp=0; tmp < num; tmp++) {
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sum_xy += (*xptr) * ( (*yhigh) - (*ylow) );
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sum_yz += (*yptr) * ( (*zhigh) - (*zlow) );
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sum_zx += (*zptr) * ( (*xhigh) - (*xlow) );
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xptr += ofs_x;
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xlow += ofs_x;
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xhigh += ofs_x;
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yptr += ofs_y;
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ylow += ofs_y;
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yhigh += ofs_y;
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zptr += ofs_z;
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zlow += ofs_z;
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zhigh += ofs_z;
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}
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out = aiVector3t<TReal>(sum_yz,sum_zx,sum_xy);
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}
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} // ! Assimp
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#endif
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