fixed issues with random walks

math/stats/Histogram.h

@@ -0,0 +1,94 @@
+#ifndef STATS_HISTOGRAM_H
+#define STATS_HISTOGRAM_H
+
+#define WITH_DEBUG_PLOT
+
+#ifdef WITH_DEBUG_PLOT
+#include <KLib/misc/gnuplot/Gnuplot.h>
+#include <KLib/misc/gnuplot/GnuplotPlot.h>
+#include <KLib/misc/gnuplot/GnuplotPlotElementLines.h>
+#endif
+
+#include <vector>
+
+namespace Stats {
+
+	template <typename Scalar> class Histogram {
+
+	#ifdef WITH_DEBUG_PLOT
+		K::Gnuplot gp;
+		K::GnuplotPlot plot;
+		K::GnuplotPlotElementLines lines;
+	#endif
+
+		Scalar min;
+		Scalar max;
+		int bins;
+		int cnt = 0;
+
+		std::vector<Scalar> counts;
+
+	public:
+
+		/** ctor */
+		Histogram(Scalar min, Scalar max, int bins) : min(min), max(max), bins(bins) {
+
+			clear();
+
+			#ifdef WITH_DEBUG_PLOT
+				plot.add(&lines);
+			#endif
+
+		}
+
+		int count() const {
+			return cnt;
+		}
+
+		void add(const Scalar x) {
+			const int idx = binIdx(x);
+			counts.at(idx) += 1;
+			++cnt;
+			if (cnt % 200 == 0) {showPlot();}
+		}
+
+		void clear() {
+			counts.clear();
+			counts.resize(bins);
+			cnt = 0;
+		}
+
+	#ifdef WITH_DEBUG_PLOT
+		void showPlot() {
+
+			lines.clear();
+
+			lines.add(K::GnuplotPoint2(-1,0));
+			for (size_t idx = 0; idx < counts.size(); ++idx) {
+				const Scalar val = binValue(idx);
+				const Scalar sum = counts[idx];
+				const K::GnuplotPoint2 gp2(val, sum);
+				lines.add(gp2);
+			}
+
+			gp.draw(plot);
+			gp.flush();
+
+		}
+	#endif
+
+	private:
+
+		int binIdx(const Scalar val) const {
+			return (val - min) / (max-min) * bins;
+		}
+
+		Scalar binValue(const int idx) {
+			return idx * (max-min) + min;
+		}
+
+	};
+
+}
+
+#endif // STATS_HISTOGRAM_H

navMesh/NavMeshRandom.h

@@ -6,6 +6,7 @@
 #include "../math/DrawList.h"
 #include "../geo/Point3.h"
 #include "../misc/PerfCheck.h"
+#include "../math/stats/Histogram.h"
 
 #include "NavMeshLocation.h"
 
@@ -20,27 +21,22 @@ namespace NM {
 	template <typename Tria> class NavMeshRandom {
 
 		DrawList<size_t> lst;
-		std::minstd_rand gen;
 		std::uniform_real_distribution<float> dOnTriangle = std::uniform_real_distribution<float>(0.0f, 1.0f);
 		std::uniform_real_distribution<float> dHeading = std::uniform_real_distribution<float>(0, M_PI*2);
 		std::vector<const Tria*> triangles;
 
-
 		uint32_t nextSeed() {
 			static uint32_t seed = 0;
-			return ++seed;
+			return seed += 13;
 		}
 
 	public:
 
 		/** ctor (const/non-const using T) */
-		template <typename T> NavMeshRandom(const std::vector<T*>& srcTriangles) : lst(nextSeed()), gen(nextSeed()) {
+		template <typename T> NavMeshRandom(const std::vector<T*>& srcTriangles) : lst(nextSeed()) {
 
 			Assert::isFalse(srcTriangles.empty(), "no triangles given. mesh is empty");
 
-			// 1st = almost always the same number?!
-			gen(); 	gen();
-
 			// construct a DrawList (probability = size[area] of the triangle
 			// bigger triangles must be choosen more often
 			for (size_t idx = 0; idx < srcTriangles.size(); ++idx) {
@@ -53,6 +49,9 @@ namespace NM {
 		/** draw a random point */
 		NavMeshLocation<Tria> draw() {
 
+			// re-use to provide stable random numbers!
+			static std::mt19937 gen;
+
 			PERF_REGION(3, "NavMeshRandom::draw()");
 
 			// pick a random triangle to draw from
@@ -63,6 +62,15 @@ namespace NM {
 			float u = dOnTriangle(gen);
 			float v = dOnTriangle(gen);
 
+#ifdef WITH_DEBUG_PLOT_2
+			static Stats::Histogram<float> histU(0, 1, 200);
+			static Stats::Histogram<float> histV(0, 1, 200);
+			if (histU.count() > 200) {histU.showPlot(); histU.clear();}
+			if (histV.count() > 200) {histV.showPlot(); histV.clear();}
+			histU.add(u);
+			histV.add(v);
+#endif
+
 			// if the (u,v) is outside of the triangle, mirror it so its inside the triangle again
 			if ((u+v) > 1) {
 				u = 1.0f - u;
@@ -78,15 +86,25 @@ namespace NM {
 		/** draw a random location within the given radius */
 		NavMeshLocation<Tria> drawWithin(const Point3 center, const float radius) {
 
+			// re-use to provide stable random numbers!
+			static std::mt19937 gen;
+
 			std::uniform_real_distribution<float> dDistance(0.001, radius);
 
 			while(true) {
+
 				const float head = dHeading(gen);
 				const float dist = dDistance(gen);
 
 				const float ox = std::cos(head) * dist;
 				const float oy = std::sin(head) * dist;
 
+#ifdef WITH_DEBUG_PLOT_2
+				static Stats::Histogram<float> hist(0, 10, 200);
+				if (hist.count() > 1000) {hist.showPlot(); hist.clear();}
+				hist.add(dist);
+#endif
+
 				// 2D destination (ignore z)
 				const Point2 dst(center.x + ox, center.y + oy);
 

navMesh/walk/NavMeshWalkParams.h

@@ -20,6 +20,7 @@ namespace NM {
 		template <typename Tria> float inMeter(const int steps, const NavMeshLocation<Tria>& start) const {
 
 			Assert::isTrue(isValid(), "invalid step-sizes given");
+			Assert::isNotNull(start.tria, "no starting triangle given");
 
 			if (start.tria->getType() == (int) NM::NavMeshType::STAIR_SKEWED) {
 				return stepSizeStair_m * steps;