71 lines
1.6 KiB
C++
71 lines
1.6 KiB
C++
#ifndef NAVMESHRANDOM_H
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#define NAVMESHRANDOM_H
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#include <random>
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#include <vector>
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#include "../math/DrawList.h"
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#include "../geo/Point3.h"
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#include "NavMeshLocation.h"
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namespace NM {
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/**
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* randomly pick points within the area of the nav-mesh.
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* points are picked evenly:
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* bigger triangles are used more often
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*
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*/
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template <typename Tria> class NavMeshRandom {
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DrawList<size_t> lst;
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std::minstd_rand gen;
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std::uniform_real_distribution<float> dOnTriangle = std::uniform_real_distribution<float>(0.0f, 1.0f);
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std::vector<const Tria*> triangles;
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uint32_t nextSeed() {
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static uint32_t seed = 0;
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return ++seed;
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}
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public:
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/** ctor (const/non-const using T) */
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template <typename T> NavMeshRandom(const std::vector<T*>& srcTriangles) : lst(nextSeed()), gen(nextSeed()) {
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// almost always the same number?!
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gen();
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// construct a DrawList (probability = size[area] of the triangle
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// bigger triangles must be choosen more often
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for (size_t idx = 0; idx < srcTriangles.size(); ++idx) {
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this->triangles.push_back(srcTriangles[idx]);
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this->lst.add(idx, srcTriangles[idx]->getArea());
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}
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}
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/** draw a random point */
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NavMeshLocation<Tria> draw() {
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// pick a random triangle to draw from
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const size_t idx = lst.get();
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const Tria* tria = triangles[idx];
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while (true) {
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const float u = dOnTriangle(gen);
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const float v = dOnTriangle(gen);
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if ((u+v) > 1) {continue;}
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const Point3 pos = tria->getPoint(u,v); //tria->getA() + (tria.getAB() * u) + (tria.getAC() * v);
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return NavMeshLocation<Tria>(pos, tria);
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}
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}
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};
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}
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#endif // NAVMESHRANDOM_H
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