src/raycast.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2016 juhdanad, Daniel Juhasz <juhdanad@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "raycast.h"
  21 #include "irr_v3d.h"
  22 #include "irr_aabb3d.h"
  23 #include "constants.h"
  24
  25 bool RaycastSort::operator() (const PointedThing &pt1,
  26         const PointedThing &pt2) const
  27 {
  28         // "nothing" can not be sorted
  29         assert(pt1.type != POINTEDTHING_NOTHING);
  30         assert(pt2.type != POINTEDTHING_NOTHING);
  31         f32 pt1_distSq = pt1.distanceSq;
  32
  33         // Add some bonus when one of them is an object
  34         if (pt1.type != pt2.type) {
  35                 if (pt1.type == POINTEDTHING_OBJECT)
  36                         pt1_distSq -= BS * BS;
  37                 else if (pt2.type == POINTEDTHING_OBJECT)
  38                         pt1_distSq += BS * BS;
  39         }
  40
  41         // returns false if pt1 is nearer than pt2
  42         if (pt1_distSq < pt2.distanceSq) {
  43                 return false;
  44         }
  45
  46         if (pt1_distSq == pt2.distanceSq) {
  47                 // Sort them to allow only one order
  48                 if (pt1.type == POINTEDTHING_OBJECT)
  49                         return (pt2.type == POINTEDTHING_OBJECT
  50                                 && pt1.object_id < pt2.object_id);
  51
  52                 return (pt2.type == POINTEDTHING_OBJECT
  53                                 || pt1.node_undersurface < pt2.node_undersurface);
  54         }
  55         return true;
  56 }
  57
  58
  59 RaycastState::RaycastState(const core::line3d<f32> &shootline,
  60         bool objects_pointable, bool liquids_pointable, bool nodes_pointable) :
  61         m_shootline(shootline),
  62         m_iterator(shootline.start / BS, shootline.getVector() / BS),
  63         m_previous_node(m_iterator.m_current_node_pos),
  64         m_objects_pointable(objects_pointable),
  65         m_liquids_pointable(liquids_pointable),
  66         m_nodes_pointable(nodes_pointable)
  67 {
  68 }
  69
  70
  71 bool boxLineCollision(const aabb3f &box, const v3f &start,
  72         const v3f &dir, v3f *collision_point, v3s16 *collision_normal)
  73 {
  74         if (box.isPointInside(start)) {
  75                 *collision_point = start;
  76                 collision_normal->set(0, 0, 0);
  77                 return true;
  78         }
  79         float m = 0;
  80
  81         // Test X collision
  82         if (dir.X != 0) {
  83                 if (dir.X > 0)
  84                         m = (box.MinEdge.X - start.X) / dir.X;
  85                 else
  86                         m = (box.MaxEdge.X - start.X) / dir.X;
  87
  88                 if (m >= 0 && m <= 1) {
  89                         *collision_point = start + dir * m;
  90                         if ((collision_point->Y >= box.MinEdge.Y)
  91                                         && (collision_point->Y <= box.MaxEdge.Y)
  92                                         && (collision_point->Z >= box.MinEdge.Z)
  93                                         && (collision_point->Z <= box.MaxEdge.Z)) {
  94                                 collision_normal->set((dir.X > 0) ? -1 : 1, 0, 0);
  95                                 return true;
  96                         }
  97                 }
  98         }
  99
 100         // Test Y collision
 101         if (dir.Y != 0) {
 102                 if (dir.Y > 0)
 103                         m = (box.MinEdge.Y - start.Y) / dir.Y;
 104                 else
 105                         m = (box.MaxEdge.Y - start.Y) / dir.Y;
 106
 107                 if (m >= 0 && m <= 1) {
 108                         *collision_point = start + dir * m;
 109                         if ((collision_point->X >= box.MinEdge.X)
 110                                         && (collision_point->X <= box.MaxEdge.X)
 111                                         && (collision_point->Z >= box.MinEdge.Z)
 112                                         && (collision_point->Z <= box.MaxEdge.Z)) {
 113                                 collision_normal->set(0, (dir.Y > 0) ? -1 : 1, 0);
 114                                 return true;
 115                         }
 116                 }
 117         }
 118
 119         // Test Z collision
 120         if (dir.Z != 0) {
 121                 if (dir.Z > 0)
 122                         m = (box.MinEdge.Z - start.Z) / dir.Z;
 123                 else
 124                         m = (box.MaxEdge.Z - start.Z) / dir.Z;
 125
 126                 if (m >= 0 && m <= 1) {
 127                         *collision_point = start + dir * m;
 128                         if ((collision_point->X >= box.MinEdge.X)
 129                                         && (collision_point->X <= box.MaxEdge.X)
 130                                         && (collision_point->Y >= box.MinEdge.Y)
 131                                         && (collision_point->Y <= box.MaxEdge.Y)) {
 132                                 collision_normal->set(0, 0, (dir.Z > 0) ? -1 : 1);
 133                                 return true;
 134                         }
 135                 }
 136         }
 137         return false;
 138 }