133 lines
3.3 KiB
C++
133 lines
3.3 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 "../misc/PerfCheck.h"
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#include "../math/stats/Histogram.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::uniform_real_distribution<float> dOnTriangle = std::uniform_real_distribution<float>(0.0f, 1.0f);
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std::uniform_real_distribution<float> dHeading = std::uniform_real_distribution<float>(0, M_PI*2);
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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 += 13;
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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()) {
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Assert::isFalse(srcTriangles.empty(), "no triangles given. mesh is empty");
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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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// re-use to provide stable random numbers!
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static std::mt19937 gen;
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PERF_REGION(3, "NavMeshRandom::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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// get random (u,v) on triangle
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float u = dOnTriangle(gen);
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float v = dOnTriangle(gen);
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#ifdef WITH_DEBUG_PLOT_2
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static Stats::Histogram<float> histU(0, 1, 200);
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static Stats::Histogram<float> histV(0, 1, 200);
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if (histU.count() > 200) {histU.showPlot(); histU.clear();}
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if (histV.count() > 200) {histV.showPlot(); histV.clear();}
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histU.add(u);
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histV.add(v);
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#endif
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// if the (u,v) is outside of the triangle, mirror it so its inside the triangle again
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if ((u+v) > 1) {
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u = 1.0f - u;
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v = 1.0f - v;
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}
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// done
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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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/** draw a random location within the given radius */
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NavMeshLocation<Tria> drawWithin(const Point3 center, const float radius) {
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// re-use to provide stable random numbers!
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static std::mt19937 gen;
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std::uniform_real_distribution<float> dDistance(0.001, radius);
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while(true) {
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const float head = dHeading(gen);
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const float dist = dDistance(gen);
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const float ox = std::cos(head) * dist;
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const float oy = std::sin(head) * dist;
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#ifdef WITH_DEBUG_PLOT_2
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static Stats::Histogram<float> hist(0, 10, 200);
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if (hist.count() > 1000) {hist.showPlot(); hist.clear();}
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hist.add(dist);
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#endif
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// 2D destination (ignore z)
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const Point2 dst(center.x + ox, center.y + oy);
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for (const Tria* t : triangles) {
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// if triangle contains 2D position
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if (t->contains(dst)) {
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// convert it to a 3D position
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const Point3 p3 = t->toPoint3(dst);
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const NavMeshLocation<Tria> loc(p3, t);
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return loc;
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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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#endif // NAVMESHRANDOM_H
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