slow intersect call

[Gladsomebeast]

Is there a collision shape defined for the wall, probably with collideMesh()? viz.phys.intersectLine() only intersects with VizPhysicsShapes, not model geometry.

[pbeeson]

Originally Posted by Gladsomebeast

Is there a collision shape defined for the wall, probably with collideMesh()? viz.phys.intersectLine() only intersects with VizPhysicsShapes, not model geometry.

Yes, collidemesh() is used. It's not all the scans, just a few of them.

[farshizzo]

Do these missed intersections occur near a triangle boundary?

[pbeeson]

Originally Posted by farshizzo

Do these missed intersections occur near a triangle boundary?

No. The thickness of the "wall" is only 0.01, maybe that has something to do with it. I'll try increasing the thickness, and see if that makes a difference.

[pbeeson]

Originally Posted by pbeeson

No. The thickness of the "wall" is only 0.01, maybe that has something to do with it. I'll try increasing the thickness, and see if that makes a difference.

Oddly, increasing the thickness of the wall made more rays NOT intersect the wall, while decreasing the thickness of the wall made more rays intersect the wall. By setting the wall thickness to 0, all rays properly see the wall, and the map I get looks like the right figure (see above thumbnails) which is correct. As I increase the thickness of the wall, more white rays go through the wall in the map I make, showing improper intersections with viz.phys.intersectLine()

Attached is the .wrl file of the environment I am using (I changed it to .txt to get it to upload). If you search and replace 0.01, you can change the thickness of walls. I start at (10.5,1.3,-21.0) with an orientation of 0.0. The rays you see in the left image that go through the wall are at about 12.25, 1.3, -17.5 (the thing in the middle in the picture is an avatar).

Hope this helps.

[farshizzo]

I can't replicate your problem. I downloaded your model and made the thickness of the wall to 1.0. I then setup a timer that would perform a 180 degree sweep of intersection tests based on the current view position/orientation. I spent a minute navigating through the maze and never got a missed intersection. Here's the script I used to test it out:

import viz
import math
viz.go()

wall = viz.add('wall_thick.wrl')
wall.collideMesh()
wall.disable(viz.DYNAMICS)

viz.MainView.translate(10.5,1.3,-21.0)

def SweepIntersection():

	#Get begin point for intersection test
	begin = viz.MainView.getPosition()
	bx = begin[0]
	by = begin[1]
	bz = begin[2]
	
	#Get point 100 units ahead of viewpoint
	forward = viz.Vector(viz.MainView.getMatrix().getForward(),length=100)
	px = forward[0]
	pz = forward[2]
	
	for deg in range(-90,90):
		
		#Rotate ahead point by deg (Assume no pitch/roll)
		rad = viz.radians(deg)
		x = math.cos(rad)*px - math.sin(rad)*pz 
		z = math.sin(rad)*px + math.cos(rad)*pz
		
		#Calculate end point
		ex = bx + x
		ez = bz + z
		
		#Perform intersection
		info = viz.phys.intersectLine(begin,(ex,by,ez))
		
		#Check if intersection is not valid
		if not info.valid:
			print 'NO INTERSECTION'

vizact.ontimer(0,SweepIntersection)

Does this problem only occur under certain conditions or is it pretty much random?

[pbeeson]

Here is code that works with the Test.wrl I posted earlier. The view is at an angle to the hallway, so a line straight ahead should intersect the wall which is 4.3 meters away. But, this particular line misses the intersection with the closest wall and intersects another wall in the environment (> 10 meters away).

This shows the different results sometimes returned by viz.phys.intersectLine() and viz.intersect().

import viz, math

viz.go()

env = viz.add('Test.wrl')
env.collidemesh()
env.disable(viz.DYNAMICS)

start_pos=[10.5, 1.3, -21.43391, 23.975]

view=viz.get(viz.MAIN_VIEWPOINT)
view.translate(start_pos[0], start_pos[1], start_pos[2])
view.rotate(0,1,0,start_pos[3], viz.BODY_ORI,viz.ABSOLUTE)

def dist(x1,y1,x2,y2):
    return math.sqrt(pow(x1-x2,2)+pow(y1-y2,2))

def timerCallback(num): 
    end_pos=[start_pos[0]+100*math.sin(start_pos[3]*math.pi/180),
             start_pos[1],
             start_pos[2]+100*math.cos(start_pos[3]*math.pi/180)]
    inters_obj = viz.phys.intersectLine(start_pos[0:3], end_pos)
    print inters_obj.intersectPoint
    print dist(inters_obj.intersectPoint[0],inters_obj.intersectPoint[2],
               start_pos[0],start_pos[2])
    inters_obj = viz.intersect(start_pos[0:3], end_pos)
    print ''
    print inters_obj.intersectPoint
    print dist(inters_obj.intersectPoint[0],inters_obj.intersectPoint[2],
               start_pos[0],start_pos[2])
    print '\n\n'

    

viz.callback(viz.TIMER_EVENT, timerCallback)
viz.starttimer(1, 1, -1)