Path: chuka.playstation.co.uk!news
From: "Peter Dollochan" <Peter.Dollochan@btinternet.com>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: Collision Detection
Date: 15 Sep 1998 17:16:35 GMT
Organization: PlayStation Net Yaroze (SCEE)
Lines: 120
Message-ID: <01bde0cb$da190e60$026f6f6f@two>
References: <35fd5208.9088684@news.playstation.co.uk>
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Hi,
Okay to keep your car in the world and assuming 
each cell is say 64X64 and the first entry is at
(0,0,0) the last is at (896,0,-896)

if(CarModel.Object_Coord.coord.t[0]<0)
{
  CarModel.Object_Coord.coord.t[0]=0;
}
if(CarModel.Object_Coord.coord.t[0]>959)
{
  CarModel.Object_Coord.coord.t[0]=959;
}

if(CarModel.Object_Coord.coord.t[2]>0)
{
  CarModel.Object_Coord.coord.t[2]=0;
}
if(CarModel.Object_Coord.coord.t[2]<-959)
{
  CarModel.Object_Coord.coord.t[2]=-959;
}
That should stop your car going of off the cell data altogether
To find out what cell the car is on again I assume the cell size
64X64.
add the declarations 
int Cell_numX,Cell_numZ;
to your object struct.....
then to tell what cell you are in use bitshifting on the positional
data of your car.

CarModel.Cell_numX = CarModel.Object_Coord.coord.t[0]>>6;
CarModel.Cell_numZ = CarModel.Object_Coord.coord.t[2]>>6;

from here its up to you what to do, you could use another couple
of variables to store the last position of the car so that in the event
that you drive of off the track (I take it you have zeros in your array
data to signify no track) you just dump the car back to the  position 
prior to leaving the track...or you could try angle of incidence/reflection
thereby giving the idea that the car bounced of off a wall or something
whatever you choose this should get you going...all this aside Phils
suggestion that you look into 2D stuff first may be the way to go and
everything I said is prolly wrong (but I hope not :-)

Pete.


Tanvir Khan <2bad@lineone.net> wrote in article
<35fd5208.9088684@news.playstation.co.uk>...
> Hi,
> 
> I am still getting nowhere with collision detection even after some
> help from George Bain's sample, so I am putting some bits of the code
> of the code I'm working on for your knowledge so you know whats going
> on.
> 
> I want a 3D car to collide once it is of the track which is made of
> cells.
> 
> The struct of the car is:
> 
> typedef struct                         
>   {                                                
>   SVECTOR         rotation;                         
>   long            speed;                              
>   GsDOBJ2         Object_Handler;                    
>   GsCOORDINATE2   Object_Coord;  
>                                                    
>   } Object_Header0;
> Object_Header0    CarModel;                           
> 
> Track struct is:
> 
> typedef struct                                      
>   {                                                   
>   long            numberObjects;                      
>   GsDOBJ2         Object_Handler[GROUND_MAX_OBJECTS];
>   GsCOORDINATE2   Object_Coord[GROUND_MAX_OBJECTS];   
>   u_long          *Back_Pointer[GROUND_MAX_OBJECTS];
> 
>   u_long          *Object_Pointer[GROUND_MAX_OBJECTS];
>   } Track_Header0;
> Track_Header0     TrackData;                
> Track_Header0     Track1Data;                          
> Track_Header0     Track2Data;                          
> Track_Header0     Track3Data;                          
> Track_Header0     Track4Data;                          
> Track_Header0     Track5Data;                          
> 
> Tack array:
> 
> char RawGroundArray[GROUND_MAXX][GROUND_MAXZ] ={
> {'6','1','1','1','1','1','2','0','0','0','0','0','0','6','2'},
> {'3','0','0','0','0','0','5','1','2','0','0','6','1','4','3'},
> {'3','0','0','0','0','0','0','0','3','0','0','3','0','0','3'},
> {'3','0','0','0','6','1','1','1','4','0','0','3','0','0','3'},
> {'3','0','0','0','3','0','0','0','0','0','0','3','0','0','3'},
> {'5','1','2','0','5','1','1','1','1','1','1','4','0','0','3'},
> {'0','0','3','0','0','0','0','0','0','0','0','0','0','0','3'},
> {'0','0','3','0','0','6','1','1','1','1','1','1','1','1','4'},
> {'0','6','4','0','0','3','0','0','0','0','0','0','0','0','0'},
> {'0','3','0','0','6','4','0','0','0','0','0','0','0','0','0'},
> {'6','4','0','0','3','0','0','0','0','0','0','0','0','0','0'},
> {'3','0','0','0','5','1','1','1','1','1','1','1','1','1','2'},
> {'3','0','0','0','0','0','0','0','0','0','0','0','0','0','3'},
> {'3','0','0','0','0','0','0','0','0','0','0','0','0','0','3'},
> {'5','1','1','1','1','1','1','1','1','1','1','1','1','1','4'}};
> 
> Can anyone please put some examples for collision detection using the
> information provided.
> 
> If anymore info is needed that's no problem.
> 
> Sorry for the trouble.
> 
> Tanvir Khan
> EMAG DESIGN
> 
> 2bad@lineone.net
>