Talk:LlCastRay

llSonar please?

I would appreciate if you took in consideration my suggestions at http://jira.secondlife.com/browse/SVC-2486 please; any feedback is more than welcome.

ps:llCastRay is already awesome, you rock! Please try the hardest you can to figure out how to get this to come to the maingrid with the least crippling as possible.

--TigroSpottystripes Katsu 03:01, 3 July 2010 (UTC)

Hi Tigro,

If I understand your feature request, it sounds much like the shape cast described in SVC-5381 (http://jira.secondlife.com/browse/SVC-5381) for a sphere or a cylinder cast along its primary axis. Is that correct?

Thanks, Falcon Linden

What am I looking at?

A function I just threw in to replace phantom bullets for quickly acquiring a point of interest -- whatever your camera's focused on (in this sim, within 20m) is returned, allowing quicker, more intuitive targeting of other objects. PERMISSION_TRACK_CAMERA must be previously set.

<lsl>key camPing() {

   // End points at the camera and 20m in front of it
   vector camPos = llGetCameraPos();
   vector endPos = camPos + ( <20.0, 0., 0.> * llGetCameraRot() );

   // Clamp the end position to within the sim
   // Except what I originally posted was wrong, and I'm too tired to do trig

   // Cast the ray; ignore hits on land, otherwise get the root key
   list contacts = llCastRay( camPos, endPos, 
       RC_REJECT_LAND,
       RC_GET_ROOT_KEY );

   // Return values
   if ( llList2Integer( contacts, -1 ) > 0 ) { // Got a return
       return llList2Key( contacts, 0 );
   }
   return NULL_KEY;

} </lsl>

Jack Abraham 04:42, 3 July 2010 (UTC)

RC_GET_LINK_NUM? Not RC_GET_LINK_KEY?

I can't think of a circumstance where knowing the link number of the return would be useful. UUID of the prim hit would be far more useful; is that within the realm of possibility? Jack Abraham 04:47, 3 July 2010 (UTC)

Hi Jack,

The default behavior is to return the UUID of the prim hit. If you want the root key instead, you have to use RC_GET_ROOT_KEY. The intended purpose of RC_GET_LINK_NUM was for scripts like your camera targeting system where it is expected that the camera will be pointed at a child of the linkset performing the cast. For example, suppose you make a minesweeper game where each tile is a prim in the linkset. And suppose you script it so that the use can select a tile by focusing on it and clicking. The script could cast a ray from the camera and determine the link number of the tile in the player's line of sight. Then it could use that link number in an llMessageLinked or some other LSL function to modify the appropriate child prim. Does that make sense? If it turns out no one has any use for RC_GET_LINK_NUM, I'll eliminate it for the sake of simplicity. But the behavior you're looking for is already there by default! Yay.

Cheers, Falcon Linden

Makes perfect sense; I need to read better. Thanks. Jack Abraham 05:44, 3 July 2010 (UTC)