After less than one week – weekend not counted in (I have had over 24hrs of sleep during weekend, I really hate to be sick) I have cought up with university material. Material covered:

- Tile system for map loaded from a file
- offset for moving map
- entity manager for all objects on the map – plus improvement
- messaging system –Â communication between instances of objects
- collision detection – and my own improvement
- moving around the map – mouse based
- font manager

Plans for next week

- Selecting objects by mouse click – hoping to select more than one element
- collision detection applied for object on a map
- placing building on the map
- shooting to zombies and other stuff.

Meanwhile I will post some code – I haven’t done that for a while.

## Collision detection class with improvements

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | // Collision.h #pragma once #ifndef COLLISION_H #define COLLISION_H const float TOUCH_DISTANCE = 0.000000000001; static enum CollisionResults { NO_COLLISION, TOUCHING, OVERLAPPING }; struct Circle{ D3DXVECTOR3& position; float radius; }; struct BoundingBox{ D3DXVECTOR3& position; D3DXVECTOR3& size; }; bool TestCollision(const BoundingBox& a, const BoundingBox& b); CollisionResults TestCollisionCircle(const Circle& a, const Circle& b); #endif |

Pretty easy stuff here – two structs for BoundingBox and Circle enum for collision between circles – I have added it because I want to base selecting objects and – well all collision on two circles.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | // Collision.cpp #include "Collision.h" bool TestCollision(const BoundingBox& a, const BoundingBox& b){ float t; if((t = a.position.x - b.position.x) > b.size.x || -t > a.size.x) return false; if((t = a.position.y - b.position.y) > b.size.y || -t > a.size.y) return false; if((t = a.position.z - b.position.z) > b.size.z || -t > a.size.z) return false; return true; } CollisionResults TestCollisionCircle(const Circle& a, const Circle& b){ //for math CollisionResults colliding; float distance_squared; float radii_squared; //a*a + b*b = c*c distance_squared = ((a.position.x - b.position.x)* (a.position.x - b.position.x))+ ((a.position.y - b.position.y)* (a.position.y - b.position.y)); //Multiplication is faster than taking a square root radii_squared = (a.radius + b.radius) * (a.radius + b.radius); if( -TOUCH_DISTANCE < radii_squared - distance_squared &&radii_squared - distance_squared < TOUCH_DISTANCE) colliding = TOUCHING; else if(radii_squared > distance_squared) colliding = OVERLAPPING; else colliding = NO_COLLISION; return colliding; } |

pretty simple stuff here as well – Pythagorean theorem based. if distance between two points is bigger than sum of radius of circles then there is no collision if it is equal there is a collision but if it is smaller they overlap – so we have covered all 3 states first two for collision detection on the map and third one for selecting. simple

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