Collision within a Radius

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On 07/04/2011 at 03:57, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   12 
Platform:   Windows  ;   
Language(s) :     C++  ;

---------
Hi everyone.

I am using teh following code to detect for collisions with the mouse and objects behind it.  If it is true, the object in my plugin highlights to show that the mouse is over that part of the tool.  The problem is that this limits the user to only being able to select the tool if the mouse is exactly over the handles which are drawn with DrawPolygonObject().

Using this method for detecting if the mouse is over the tool is fine but I would like to be able to set a radius for the tool and if the tool is within that radius it is also selected.  Does anyone know how I coiuld acheive this while incorporating the code below.   :)

Thanks,

Shawn

  
//CHECK FOR COLLISIONS  
//=============================================//  
Bool UniversalManipulator::IsCollision(PolygonObject *pObj, BaseDraw *bd){  
  
  AutoAlloc<GeRayCollider> cRay;  
  if (!cRay) return FALSE;  
  
  GeRayColResult res;  
  
  Real x = cursorX;  
  Real y = cursorY;  
  
  // Make sure RayCollider is there  
  if (!cRay)  
  {  
      GePrint("ERROR - RayCollider not Initialized");  
      return FALSE;  
  }  
  
  Vector wtail =    bd->SW(Vector(x, y, 0));  
  Vector whead =    bd->SW(Vector(x, y, 1000000));  
  Vector otail = (!pObj->GetMg()) * wtail;  
  Vector oray     = (whead - wtail) ^ (!pObj->GetMg());  
  
  
  cRay->Init(pObj, TRUE);  
  cRay->Intersect(otail, !oray, 1000000.0);  
  
  
  if (cRay->GetNearestIntersection(&res))  
  {  
      //GePrint("A COLLISION HAS OCCURED");  
      return TRUE;  
  }  
  
  return FALSE;  
}  

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On 07/04/2011 at 05:24, xxxxxxxx wrote:

Hey Shawn,

What is, if you do more intersections like:

wtail1 =    bd->SW(Vector(x, y, 0));  
wtail2 =    bd->SW(Vector(x+1, y+1, 0));  
wtail3 =    bd->SW(Vector(x+1, y, 0));  
wtail4 =    bd->SW(Vector(x-1, y, 0));

And so one. ;) Use the http://en.wikipedia.org/wiki/Unit_circle for more points and maybe a loop between the circle. ;)

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On 07/04/2011 at 08:14, xxxxxxxx wrote:

You cold try using PointLineDistance instead. If the distance from the handle to the ray is less than the desired radius, you have a hit.

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On 07/04/2011 at 09:35, xxxxxxxx wrote:

So if I wanted to use PointLineDistance()...
 
Would it be like this?
 
 
PointLineDistance(wtail, whead, res.hitpos);
 
Also, is the Vector that is returned by this function the distance fromt the point to the ray?

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On 07/04/2011 at 09:44, xxxxxxxx wrote:

Or would I instead do:
 
PointLineDistance(wtail, oray, res.hitpos);

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On 07/04/2011 at 13:32, xxxxxxxx wrote:

okay using the last code i posted the res.hitpos always returns 0,0,0

Anyone have any idea why?

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On 07/04/2011 at 14:52, xxxxxxxx wrote:

(0,0,0) is correct.

Because you calculate the distance between your 'intersection line' and a hit point of the intersection.

A Point at a line = distance = 0. ;)

You should do it maybe with points of a polygon near the hit point.

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On 07/04/2011 at 16:16, xxxxxxxx wrote:

Like this?

Vector distance = PointLineDistance(wtail, oray, pObj->GetMg().off);

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On 07/04/2011 at 16:25, xxxxxxxx wrote:

How does the vector returned by PointLineDistance() represent the distance,,,  what does each Real in the Vector represent?

for example   when I use the above line I get a bunch of different numbers and those numbers do not seem to be the same when the camera is in different places..

Hopefully that makes sense..  lol

~Shawn

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On 07/04/2011 at 16:44, xxxxxxxx wrote:

The ray should be in the same space as the object and the shortest distance is the length of the returned vector.

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On 07/04/2011 at 17:27, xxxxxxxx wrote:

okay I've got it work using

  
  
Vector distance = PointLineDistance(wtail, whead, pObj->GetMg().off);  
  Real disX = distance.x;  
  Real disY = distance.y;  
  Real disZ = distance.z;  
  
  //if (cRay->GetNearestIntersection(&res))  
  if((disX > -20 && disX < 20) && (disY > -20 && disY < 20) && (disZ > -20 && disZ < 20))    
  {  
      //GePrint("A COLLISION HAS OCCURRED");  
      return TRUE;  
  }  
  

now in order to make this whole thing work the right way I need to be able to capture the initial mouse location when the mouse is clicked and dragged and then not get the mouse location while it is dragging..   So basically I want the mouse location where the user clicks but then I don't want the location while the mouse is dragging.

Is this possible...  I currently use BFM_INPUT_X & BFM_INPUT_Y  to get the mouse location but this value changes as the mouse is dragging.

Thanks,

Shawn

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On 07/04/2011 at 18:24, xxxxxxxx wrote:

Just use GetLength(), e.g.

const Real threshold = 10.0;   
Real dist = result.GetLength();   
if(dist <= threshold) return TRUE;

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On 07/04/2011 at 18:35, xxxxxxxx wrote:

Thank you David that is much cleaner..  :)

  
  Vector distance = PointLineDistance(wtail, whead, pObj->GetMg().off);  
  const Real threshold = 20.0;  
  Real dist = distance.GetLength();  
    
  if(dist <= threshold)    
  {  
      //GePrint("A COLLISION HAS OCCURED");  
      return TRUE;  
  }  

Anyone know about getting the mouse position of the initial click when doing a mouse drag?

Thanks,

Shawn

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On 07/04/2011 at 23:12, xxxxxxxx wrote:

Hello,
a question where you perform this?
if you hare in mouse input you can use ViewPortSelect::PickObject()
this will fill a c4dobjectlist with all obj in the radius in z order.
it will have not very good performance but can solve the situation.

try it

all the best
Franz

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On 08/04/2011 at 02:50, xxxxxxxx wrote:

Hi Franz.   Thanks,   I am able to select within a set radius now.  See the last code I posted.  Now I am trying to figure out how to capture the screen coordinates of the first initial mouse click when the user drags the mouse.  I do not want to keep storing the mouse position after that first click so I need to figure out how to store only that first click.  :)

Thanks,

Shawn

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On 08/04/2011 at 07:40, xxxxxxxx wrote:

This is from the liquid draw example in the SDK.
Seems to work.

Real mx = msg.GetReal(BFM_INPUT_X);  
Real my = msg.GetReal(BFM_INPUT_Y);  
GePrint(RealToString(mx));  
GePrint(RealToString(my));  

-ScottA

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On 08/04/2011 at 08:27, xxxxxxxx wrote:

Howdy,

Originally posted by xxxxxxxx

...Now I am trying to figure out how to capture the screen coordinates of the first initial mouse click when the user drags the mouse.  I do not want to keep storing the mouse position after that first click so I need to figure out how to store only that first click....

If you store the mouse x and y in local variables startx and starty, and do that before the while loop, those variables won't change during the dragging.  :wink:

Adios,
Cactus Dan