scummvm/engines/freescape/sweepAABB.cpp

102 lines
3.3 KiB
C++

/* 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;
}
}