Game Development Community

Filter Filter
dev|Pro Game Development Curriculum

A simple Raycast between t2dSceneObject(s) in TGB 1.7.2

by James Ford · 04/03/2008 (10:30 am) · 3 comments

Its a bit confusing mucking around in t2dPhysics, but since I figured it out I thought I would pass it on.

You actually have all the info inside the t2dPhysics::cCollisionStatus structure but I am only returning distance because thats all I needed ... so return/use whatever you need.


// helpers.h...
#ifndef _HELPERS_H_
#define _HELPERS_H_

#ifndef _T2DSCENEOBJECT_H_
#include "T2D/t2dSceneObject.h"
#endif

struct CastRayInfo
{
    t2dVector point;
    t2dVector normal;
    F32 distance;
};

#endif // _HELPERS_H_

// helpers.cpp:
#include "console/consoleTypes.h"
#include "helpers.h"


bool castray( t2dSceneObject *srcObj, t2dSceneObject *dstObj, CastRayInfo& info )
{
    t2dPhysics srcPhy = srcObj->getParentPhysics();
    t2dPhysics dstPhy = dstObj->getParentPhysics();

    t2dVector oldvel( srcPhy.getNetLinearVelocity() );
    t2dVector testvel( dstObj->getPosition() - srcObj->getPosition() );
    srcPhy.setGrossLinearVelocity( testvel );

    t2dPhysics::cCollisionStatus status;
   
    status.mSrcObject = srcObj;
    status.mDstObject = dstObj;
    status.mpSrcPhysics = &srcPhy;
    status.mpDstPhysics = &dstPhy;           
   
    bool result = t2dPhysics::calculateCollision( 1.0f, &status );

    if ( result )
    {
       info.distance = testvel.len() * status.mCollisionTimeReal;
       info.point = status.mSrcContacts[0];
       info.normal = status.mCollisionNormal;
    }

    srcPhy.setGrossLinearVelocity( oldvel );

    return result;   
 }

ConsoleFunction( castray, F32, 3, 3, "castray( sceneObject srcObj, sceneObject dstObj )" )
{
   t2dSceneObject *srcObj = NULL;
   t2dSceneObject *dstObj = NULL;
   
   if ( !Sim::findObject( argv[1], srcObj );
      return NULL;

   if ( !Sim::findObject( argv[2], dstObj ) )
      return NULL;

   CastRayInfo info;
   if ( !castray( srcObj, dstObj, info ) )
      return NULL;

   return info.distance;
}
NextNext resource
PrevPrevious resource
More resources


Associate James Ford
Sickhead Games
#1
03/20/2008 (10:45 pm)
I recently noticed t2dSceneObject::castCollision, which does something very similar to this.

castCollision is ideal for seeing what you would hit first given a velocity and time.

However, if you want to test the distance between two specific objects, "castray" should do what you want with less overhead.

Torque Owner Don Hogan
#2
04/05/2008 (6:49 pm)
Very nice James, I have a project on the back burner that this will definitely be good for. Thank you!

Torque Owner Eyaly
#3
07/29/2008 (1:00 pm)
Thanks James , This code are really really usefull.