| 1 | /* |
| 2 | * Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com. |
| 3 | * |
| 4 | * This program is free software: you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation, either version 3 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 16 | */ |
| 17 | |
| 18 | #include "collisionManager.h" |
| 19 | #include "debug.h" |
| 20 | |
| 21 | #include "Vector2.h" |
| 22 | |
| 23 | #include "Entities/Ball.h" |
| 24 | #include "Entities/PhysicsEntity.h" |
| 25 | |
| 26 | #include "CollisionInfo.h" |
| 27 | |
| 28 | /// ***** Private Class Header ***** |
| 29 | |
| 30 | /// ***** Private Method Headers ***** |
| 31 | |
| 32 | void clearEntities(); |
| 33 | void placeEntity(PhysicsEntity* p); |
| 34 | void updateEntities(); |
| 35 | |
| 36 | void applyCollision(PhysicsEntity* p1, PhysicsEntity* p2); |
| 37 | void applyCollision(Ball* b1, Ball* b2); |
| 38 | |
| 39 | bool getInfo(Ball* b1, Ball* b2, CollisionInfo* cInfo); |
| 40 | |
| 41 | /// ***** Private Variables ***** |
| 42 | |
| 43 | const int xDivisions = 20; |
| 44 | const int yDivisions = 16; |
| 45 | const int screenX = 800; |
| 46 | const int screenY = 600; |
| 47 | |
| 48 | setPhys divisions[xDivisions][yDivisions]; |
| 49 | |
| 50 | /// ***** Initializers/Cleaners ***** |
| 51 | |
| 52 | void collision::init() |
| 53 | { |
| 54 | |
| 55 | } |
| 56 | void collision::clean() |
| 57 | { |
| 58 | |
| 59 | } |
| 60 | |
| 61 | /// ***** Public Methods ***** |
| 62 | |
| 63 | void collision::update(setPhys& sp) |
| 64 | { |
| 65 | clearEntities(); |
| 66 | |
| 67 | for( setPhys::iterator it = sp.begin(); |
| 68 | it != sp.end(); |
| 69 | it++ ) |
| 70 | { |
| 71 | placeEntity(*it); |
| 72 | } |
| 73 | |
| 74 | updateEntities(); |
| 75 | } |
| 76 | |
| 77 | /// ***** Private Methods ***** |
| 78 | |
| 79 | void clearEntities() |
| 80 | { |
| 81 | for( int x = 0; |
| 82 | x < xDivisions; |
| 83 | x++ ) |
| 84 | { |
| 85 | for( int y = 0; |
| 86 | y < yDivisions; |
| 87 | y++ ) |
| 88 | { |
| 89 | divisions[x][y].clear(); |
| 90 | } |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | void placeEntity(PhysicsEntity* p) |
| 95 | { |
| 96 | Ball* b = dynamic_cast<Ball*>(p); |
| 97 | |
| 98 | if( b == NULL ) |
| 99 | { |
| 100 | DPF(0, "ENTITY TYPE NOT SUPPORTED BY placeEntity()!!"); |
| 101 | return; |
| 102 | } |
| 103 | |
| 104 | const float& xb = b->positionRaw().x; |
| 105 | const float& yb = b->positionRaw().y; |
| 106 | const float& rad = b->radius; |
| 107 | |
| 108 | for( int x = static_cast<int>( (xb - rad) / (screenX / xDivisions) ); |
| 109 | x <= static_cast<int>( (xb + rad) / (screenX / xDivisions) ); |
| 110 | x++ ) |
| 111 | { |
| 112 | if(x < 0 || xDivisions <= x) |
| 113 | break; |
| 114 | |
| 115 | for( int y = static_cast<int>( (yb - rad) / (screenY / yDivisions) ); |
| 116 | y <= static_cast<int>( (yb + rad) / (screenY / yDivisions) ); |
| 117 | y++ ) |
| 118 | { |
| 119 | if(y < 0 || yDivisions <= y) |
| 120 | break; |
| 121 | |
| 122 | divisions[x][y].insert(p); |
| 123 | } |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | void updateEntities() |
| 128 | { |
| 129 | for( int x = 0; |
| 130 | x < xDivisions; |
| 131 | x++ ) |
| 132 | { |
| 133 | for( int y = 0; |
| 134 | y < yDivisions; |
| 135 | y++ ) |
| 136 | { |
| 137 | for( setPhys::iterator it1 = divisions[x][y].begin(); |
| 138 | it1 != divisions[x][y].end(); |
| 139 | it1++ ) |
| 140 | { |
| 141 | for( setPhys::iterator it2 = divisions[x][y].begin(); |
| 142 | it2 != divisions[x][y].end(); |
| 143 | it2++ ) |
| 144 | { |
| 145 | if( *it1 != *it2 ) |
| 146 | { |
| 147 | applyCollision(*it1, *it2); |
| 148 | } |
| 149 | } |
| 150 | } |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | void applyCollision(PhysicsEntity* p1, PhysicsEntity* p2) |
| 156 | { |
| 157 | Ball* b1 = dynamic_cast<Ball*>(p1); |
| 158 | Ball* b2 = dynamic_cast<Ball*>(p2); |
| 159 | |
| 160 | if( b1 != NULL && b2 != NULL ) |
| 161 | { |
| 162 | applyCollision(b1, b2); |
| 163 | return; |
| 164 | } |
| 165 | |
| 166 | DPF(0, "ENTITY TYPE NOT SUPPORTED BY applyCollision()!!"); |
| 167 | } |
| 168 | |
| 169 | void applyCollision(Ball* b1, Ball* b2) |
| 170 | { |
| 171 | CollisionInfo cInfo; |
| 172 | |
| 173 | if(!getInfo(b1, b2, &cInfo)) |
| 174 | return; |
| 175 | |
| 176 | // a few values to simplify the equations |
| 177 | const Vector2& normal = cInfo.normal; |
| 178 | const Vector2& point = cInfo.point; |
| 179 | |
| 180 | float m1 = b1->mass; |
| 181 | float m2 = b2->mass; |
| 182 | |
| 183 | float e = (b1->CoR + b2->CoR) / 2; |
| 184 | |
| 185 | Vector2 v1 = b1->velocityRaw(); |
| 186 | Vector2 v2 = b2->velocityRaw(); |
| 187 | |
| 188 | |
| 189 | float iTop = -(e + 1) * (v1 - v2).dot(normal); |
| 190 | |
| 191 | // otherwise the collision happened and we do the math the below assumes |
| 192 | // collisions have no friction |
| 193 | |
| 194 | float impulse = iTop / (normal.dot(normal) * (1 / m1 + 1 / m2)); |
| 195 | |
| 196 | b1->applyImpulse(impulse / m1 * normal, point); |
| 197 | b2->applyImpulse(-impulse / m2 * normal, point); |
| 198 | } |
| 199 | |
| 200 | bool getInfo(Ball* b1, Ball* b2, CollisionInfo* pcInfo) |
| 201 | { |
| 202 | // a few values to simplify the equations |
| 203 | float r1 = b1->radius; |
| 204 | float r2 = b2->radius; |
| 205 | |
| 206 | Vector2 p1 = b1->positionRaw(); |
| 207 | Vector2 p2 = b2->positionRaw(); |
| 208 | Vector2 v1 = b1->velocityRaw(); |
| 209 | Vector2 v2 = b2->velocityRaw(); |
| 210 | |
| 211 | // quick binding box check |
| 212 | if (p1.x - r1 > p2.x + r2 |
| 213 | || p1.x + r1 < p2.x - r2 |
| 214 | || p1.y - r1 > p2.y + r2 |
| 215 | || p1.y + r1 < p2.y - r2) |
| 216 | return false; |
| 217 | |
| 218 | // test if not touching |
| 219 | if ((p1 - p2).sqrLength() >= (r1 + r2)*(r1 + r2)) |
| 220 | return false; |
| 221 | |
| 222 | // test if they are moving apart in some way if they aren't it's likely |
| 223 | // that they collided last frame and are still overlapping |
| 224 | |
| 225 | if ((v1 - v2).dot(p1 - p2) >= 0) |
| 226 | return false; |
| 227 | |
| 228 | pcInfo->point = p1 - (p1 - p2) * r1 / (r1 + r2); |
| 229 | pcInfo->normal = p1 - p2; |
| 230 | |
| 231 | return true; |
| 232 | } |