Initial commit

engines/freescape/sweepAABB.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "freescape/freescape.h"
+
+namespace Freescape {
+
+/*
+This code is inspired by the Luis Eduard Reis implementation:
+https://luisreis.net/blog/aabb_collision_handling/
+*/
+
+float lineToPlane(Math::Vector3d const &p, Math::Vector3d const &u,  Math::Vector3d const &v, Math::Vector3d const &n) {
+	float NdotU = n.dotProduct(u);
+	if (NdotU == 0)
+		return INFINITY;
+
+	return n.dotProduct(v - p) / NdotU;
+}
+
+bool between(float x, float a, float b) {
+	return x >= a && x <= b;
+}
+
+float sweepAABB(Math::AABB const &a, Math::AABB const &b, Math::Vector3d const &direction, Math::Vector3d &normal) {
+	Math::Vector3d m = b.getMin() - a.getMax();
+	Math::Vector3d mh = a.getSize() + b.getSize();
+
+	float h = 1.0;
+	float s = 0.0;
+	Math::Vector3d zero;
+
+	// X min
+	s = lineToPlane(zero, direction, m, Math::Vector3d(-1, 0, 0));
+	if (s >= 0 && direction.x() > 0 && s < h && between(s * direction.y(), m.y(), m.y() + mh.y()) && between(s * direction.z(), m.z(), m.z() + mh.z())) {
+		h = s;
+		normal = Math::Vector3d(-1, 0, 0);
+	}
+
+	// X max
+	m.x() = m.x() + mh.x();
+	s = lineToPlane(zero, direction, m, Math::Vector3d(1, 0, 0));
+	if (s >= 0 && direction.x() < 0 && s < h && between(s * direction.y(), m.y(), m.y() + mh.y()) && between(s * direction.z(), m.z(), m.z() + mh.z())) {
+		h = s;
+		normal = Math::Vector3d(1, 0, 0);
+	}
+
+	// Y min
+	m.x() = m.x() - mh.x();
+	s = lineToPlane(zero, direction, m, Math::Vector3d(0, -1, 0));
+	if (s >= 0 && direction.y() > 0 && s < h && between(s * direction.x(), m.x(), m.x() + mh.x()) && between(s * direction.z(), m.z(), m.z() + mh.z())) {
+		h = s;
+		normal = Math::Vector3d(0, -1, 0);
+	}
+
+	// Y max
+	m.y() = m.y() + mh.y();
+	s = lineToPlane(zero, direction, m, Math::Vector3d(0, 1, 0));
+	if (s >= 0 && direction.y() < 0 && s < h && between(s * direction.x(), m.x(), m.x() + mh.x()) && between(s * direction.z(), m.z(), m.z() + mh.z())) {
+		h = s;
+		normal = Math::Vector3d(0, 1, 0);
+	}
+
+
+	// Z min
+	m.y() = m.y() - mh.y();
+	s = lineToPlane(zero, direction, m, Math::Vector3d(0, 0, -1));
+	if (s >= 0 && direction.z() > 0 && s < h && between(s * direction.x(), m.x(), m.x() + mh.x()) && between(s * direction.y(), m.y(), m.y() + mh.y())) {
+		h = s;
+		normal = Math::Vector3d(0, 0, -1);
+	}
+
+	// Z max
+	m.z() = m.z() + mh.z();
+	s = lineToPlane(zero, direction, m, Math::Vector3d(0, 0, 1));
+	if (s >= 0 && direction.z() < 0 && s < h && between(s * direction.x(), m.x(), m.x() + mh.x()) && between(s * direction.y(), m.y(), m.y() + mh.y())) {
+		h = s;
+		normal = Math::Vector3d(0, 0, 1);
+	}
+
+	return h;
+}
+
+}