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I am currently using a raycast in my game for a red laser sight on a weapon. It works pretty well but it is colliding with the sensors which are used throughout my levels. The code is almost identical to the testbed version, for a temporary solution i have added the line in below, but this causes the raycast to go through everything!



Any help is appreciated!

Thought I would bump this

Huh. I changed the testbed so it has a sensor that it can ignore. My code is essentially the same as yours, but works. Take a look in the repository on github.

Thanks yes this is pretty much the same as mine. This doesnt work for my purpose however - I need the raycast to still collide with objects behind the sensor...

Like gun with laser >>>>>>>>> Sensor >>>>>>>> Wall

At the moment it would ignore the sensor, then ignore the wall also.

Ok, you're right. I didn't test objects behind the sensor. it seems like half the time it can detect it and half the time it can't. Very strange... will have to look into.

Thanks mayobutter

**edit** this was my original misconception. my next post has it right.

I'm not sure if returning fraction is the right approach.

I've been testing b2World.as RayCast(); in the WCK framework.

the raycast would return multiple walls, but would seemingly draw the closest one if i graphics.clear() at the start of drawing on the callback function.

but would trace 3 sometimes 4 fixtures. and if i moved the graphics.clear() to the EnterFrame before the RayCast call, and made my lineStyle transparent, i could see that it was drawing each of the results.

simply returning 0 seems to stop further results. and leaves me with just the closest result.
returning 1 seemed to keep searching farther away, returning all possible results.

you may want to try returning 1 for sensors, and 0 for walls.

i hypothesize that returning a value other than 1, and 0, would be used if the RayCast hit an object that Amplified(greater than 1) or Depleted(greater than 0, less than 1) the range of the RayCast.

i was also pleased to see the Normal of the raycast easily accessible for creating reflections (new RayCasts along the normal) very exciting!

(side note, older RayCasts allowed you to pass a FilterFunction of sorts, but were not easy to learn to use)

oops i was making assumptions

http://www.box2d.org/manual.html#_Toc258082976

this was informative

return -1 to filter your contact.

also i need to reprogram mine to not assume the order of the callbacks are by distance.
this explains a lot of my problems

here is my new callback function;
i set closestFixture and closestPoint to null before i call the RayCast, and if they are still null afterwards i draw the full line.




hope this helps.

Brilliant this has fixed my problem, instead of returning fraction to filter the sensor I now just return -1

For ignoring sensors by raycast you just need to add in RayCast function (b2World.as class) this:



instead of this: