initial commit, 4.5 stable

core/math/bvh_pair.inc

@@ -0,0 +1,72 @@
+public:
+// note .. maybe this can be attached to another node structure?
+// depends which works best for cache.
+struct ItemPairs {
+	struct Link {
+		void set(BVHHandle h, void *ud) {
+			handle = h;
+			userdata = ud;
+		}
+		BVHHandle handle;
+		void *userdata;
+	};
+
+	void clear() {
+		num_pairs = 0;
+		extended_pairs.reset();
+		expanded_aabb = BOUNDS();
+	}
+
+	BOUNDS expanded_aabb;
+
+	// maybe we can just use the number in the vector TODO
+	int32_t num_pairs;
+	LocalVector<Link> extended_pairs;
+
+	void add_pair_to(BVHHandle h, void *p_userdata) {
+		Link temp;
+		temp.set(h, p_userdata);
+
+		extended_pairs.push_back(temp);
+		num_pairs++;
+	}
+
+	uint32_t find_pair_to(BVHHandle h) const {
+		for (int n = 0; n < num_pairs; n++) {
+			if (extended_pairs[n].handle == h) {
+				return n;
+			}
+		}
+		return uint32_t(-1);
+	}
+
+	bool contains_pair_to(BVHHandle h) const {
+		return find_pair_to(h) != BVHCommon::INVALID;
+	}
+
+	// return success
+	void *remove_pair_to(BVHHandle h) {
+		void *userdata = nullptr;
+
+		for (int n = 0; n < num_pairs; n++) {
+			if (extended_pairs[n].handle == h) {
+				userdata = extended_pairs[n].userdata;
+				extended_pairs.remove_at_unordered(n);
+				num_pairs--;
+				break;
+			}
+		}
+
+		return userdata;
+	}
+
+	// experiment : scale the pairing expansion by the number of pairs.
+	// when the number of pairs is high, the density is high and a lower collision margin is better.
+	// when there are few local pairs, a larger margin is more optimal.
+	real_t scale_expansion_margin(real_t p_margin) const {
+		real_t x = real_t(num_pairs) * (1.0 / 9.0);
+		x = MIN(x, 1.0);
+		x = 1.0 - x;
+		return p_margin * x;
+	}
+};