object/poly behind mouse cursor

Helper

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On 06/07/2008 at 11:23, xxxxxxxx wrote:

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---------
Hi,

i want to get info about the polygon 'behind' the mouse cursor, that is its position and normal direction.

i realize there's the viewportSelect::getPolyInfo() and so on, but i cant quite get it to work

it seems i have to init the viewportselect with an object, but im not sure which object to use, bc as i see it, all objects of the scene may potentially be behind the mouse cursor.. sp why do i have to choose one and init the viewportselect with it ?

anybody has some experience with this ?

thanks,
cineast

Helper

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On 06/07/2008 at 11:37, xxxxxxxx wrote:

im gettings the feeling im on the wrong track using viewportselect.

maybe its better to use geRayCollider and shoot a ray from the mouse cursor screen pos into viewport space.
the rayCollider::Intersect needs an object as argument too though, to check if it collides with the ray..

so do i have to loop through all objects in my scece to figure out which one is behind the mouse cursor ?

Helper

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On 07/07/2008 at 01:58, xxxxxxxx wrote:

ok nevermind, meanwhile i found the solution in another post here..

Helper

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On 14/07/2008 at 02:48, xxxxxxxx wrote:

It would be maybe interesting for the other forum members to know how you solved the problem. Maybe you can share what you have found out.

cheers,
Matthias

Helper

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On 14/07/2008 at 03:01, xxxxxxxx wrote:

of course, forgot about tat sry

im using GeRayCollider to shoot rays from my eye through the mouse cursor, just like superman would do

in the code below im checking if the ray hits the currently active object:

> \> AutoAlloc<GeRayCollider> rc; \> if (!rc) return FALSE; \> // the object i want to know if it was hit \> BaseObject\* obj = doc->GetActiveObject(); \> \> Vector wtail = bd->SW(Vector(mx,my,0)); \> Vector whead = bd->SW(Vector(mx,my,10000.0)); \> Vector otail = (!obj->GetMg()) \* wtail; \> Vector oray = (whead - wtail) ^ (!obj->GetMg()); \> \> // init rayCollider with object to check ray collisions on \> rc->Init(obj,TRUE); \> // check for intersection, 10000 is the length of the ray \> rc->Intersect(otail, !oray, 10000.0); \> \> // if a ray has hit the object \> if(rc->GetNearestIntersection(&res;)){ \> . \> . \> // res.hitpos has the hit position \> // and res.f_normal is the normal vec of the hit polygon \> . \> . \> } \>

the stuff with the computation on the right vector, i found using the forum search here.

Helper

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On 14/07/2008 at 03:03, xxxxxxxx wrote:

Thanks for sharing

cheers,
Matthias

Helper

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On 02/04/2011 at 05:25, xxxxxxxx wrote:

Hi,

I am trying this exact thing and am not getting any results.

Here's the code I am using.

  
  
  BaseObject* pObj = doc->GetActiveObject();  
  if(!pObj) return FALSE;  
  
  AutoAlloc<GeRayCollider> cRay;  
  if (!cRay) return FALSE;  
  
  GeRayColResult res;  
  
  // Make sure RayCollider is there  
  if (!cRay)  
  {  
      GePrint("ERROR - RayCollider not Initialized");  
      return FALSE;  
  }  
  
  Vector wtail =    bd->SW(Vector(x, y, UM_START));  
  Vector whead =    bd->SW(Vector(x, y, UM_END)) - wtail;  
  Vector otail = (!pObj->GetMg()) * wtail;  
  Vector oray     = (whead - wtail) ^ (!pObj->GetMg());  
  
  
  cRay->Init(pObj, TRUE);  
  cRay->Intersect(otail, !oray, 10000.0);  
  
  
  if (cRay->GetNearestIntersection(&res))  
  {  
      GePrint("A COLLISION HAS OCCURED");  
      return TRUE;  
  }  
  
  return TRUE;

I am not seeing anything in the console that says "A COLLISION HAS OCCURED" when I put my mouse over the active object... Does anyone see a reason why my code wouldn't work?

Thanks,

Shawn

EDIT: DOH! I figured it out. My collider was too short. Remember size does matter.

Helper

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On 02/04/2011 at 11:44, xxxxxxxx wrote:

Is there a more complete example of this?

I'm assuming that bd is a parameter used with this class method:
virtual DRAWRESULT Draw (BaseObject *op, DRAWPASS type, BaseDraw *bd, BaseDrawHelp *bh);

So I'm also assuming that the DRAWRESULT method needs to also be used.
But what goes inside of it?

Can anyone provide a more complete example of this?

-ScottA

Helper

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On 02/04/2011 at 11:51, xxxxxxxx wrote:

what specifically would you like to achieve with it? I could be more specific if I knew what you were looking to do.

To answer your first question, bd is the BaseDraw that is allocated in my function. In my case I am calling my function from the Draw() function which also allocates a BaseBraw so I just use the bd from that function and pass it to my own.

If you'd like I can repost the code I posted above with more comments to explain what each thing does.

Helper

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On 02/04/2011 at 12:21, xxxxxxxx wrote:

Hi Shawn,
I'm just trying to learn how to do basic ray collision that prints a message to the console when the mouse is over an object.

I think I understand the code that's been posted so far. But it's only a small portion of the entire .cpp file. And I'm having trouble building the stuff that's not been listed to make it work.
Namely the classes and the methods.

-ScottA

Helper

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On 02/04/2011 at 12:32, xxxxxxxx wrote:

The code above is coming from a ToolData plugin. You could put the following code in the Draw() function of a tooldata plugin,

  
  
TOOLDRAW MyClass::Draw(BaseDocument* doc, BaseContainer& data, BaseDraw* bd, BaseDrawHelp* bh, BaseThread* bt, TOOLDRAWFLAGS flags){  
    
    
    BaseObject* pObj = doc->GetActiveObject();  
      if(!pObj) return TOOLDRAW_0;  
      
      AutoAlloc<GeRayCollider> cRay;  
      if (!cRay) return TOOLDRAW_0;  
      
      GeRayColResult res;  
      
      // Make sure RayCollider is there  
      if (!cRay)  
      {  
          GePrint("ERROR - RayCollider not Initialized");  
          return TOOLDRAW_0;  
      }  
      
      Vector wtail =    bd->SW(Vector(mouseX, mouseY, 0));  
      Vector whead =    bd->SW(Vector(mouseX, mouseY, 100000));  
      Vector otail = (!pObj->GetMg()) * wtail;  
      Vector oray     = (whead - wtail) ^ (!pObj->GetMg());  
      
      
      cRay->Init(pObj, TRUE);  
      cRay->Intersect(otail, !oray, 10000.0);  
      
      
      if (cRay->GetNearestIntersection(&res))  
      {  
          GePrint("A COLLISION HAS OCCURED");  
      }  
      
      return TOOLDRAW_0;  
      
    }

mouseX and mouseY are global Reals.  Both declared as global variables.   Then in the GetCursorInfo()  you would simply put

  
      
    Bool MyClass::GetCursorInfo(BaseDocument* doc, BaseContainer& data, BaseDraw* bd, Real x, Real y, BaseContainer& bc){  
      
    mouseX = x;  
    mouseY = y;  
    if (x > -1.0f)     SpecialEventAdd(EVMSG_UPDATEHIGHLIGHT);  
      
    return TRUE;  
      
    }

This should give you a working model to learn from.   :)  
  
  
Hope that helps.  
  
~Shawn

_<_h4_>__<_h4_>_/h4>

Helper

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On 02/04/2011 at 13:06, xxxxxxxx wrote:

Thanks Shawn.
Got it working now.

BTW: Did you ever figure out how to merge documents?

-ScottA

Helper

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On 02/04/2011 at 13:11, xxxxxxxx wrote:

I did. I don't have the code here though because i am not home.. send me a PM at c4d cafe to remind me and i will send it to you when i get home. I keep forgetting to send it to you cuz when i get outa work i get focused on other things lol

sorry about that.

~Shawn

Helper

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On 02/04/2011 at 14:07, xxxxxxxx wrote:

I'm not a member there.

My e-mail is: [email protected]

Thanks,
-ScottA