WorldViz User Forum Headlight Question
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#1
02-25-2011, 09:47 AM
 new_horizon Member Join Date: Apr 2010 Posts: 43

Hi All,

Another question regarding lighting :-) I am trying to create motorcycle headlights that illuminate the road as they travel forward - I have created the following, which seems to work - but with a slightly strange effect...

(Please note, you can insert any image in place of "tarmac.jpg"

import viz
import vizact
import math
import random
from numpy import *
viz.go()

#Set the viewpoint's position and orientation so that we'll be able to see our scene.
viz.MainView.setPosition( [0,0.8,20 ] )
viz.MainView.setEuler( [-180,4, 0] )

#Disable the default head light.

# Add directional light source
sun_light.position(0,100,-70,1)
# Give light sunish color and intensity
sun_light.color ([1,1,1])
sun_light.intensity(-1)

ball.appearance(viz.TEXMODULATE)

ball.setPosition([ 0 , 10.75 , 0 ])

#Add a model of a torch and place it in the scene.
# Create headlight shape
viz.startlayer(viz.POLY_FILL)
viz.vertexcolor(1,1,1)
NUM_DOTS = 10000.0
for i in range(0, NUM_DOTS):
angle= 360.0*(i/NUM_DOTS)
# Put a vertex at each of these, but jump back to zero in between
viz.vertex(0,0)
viz.vertex(x,y)
headlight1.setPosition( [ 0 , 0 , -20 ])
#Add a light for the torch.
#Make the light positional.
flash_light.position(0,0,0,1)
flash_light.intensity(100)
#Make this positional light a spot light by limiting its spread.
#flash_light.spotexponent( 10 )
flash_light.constantattenuation(0)
flash_light.linearattenuation(1)

#Link the light source to the torch.

Can anyone shed any light on what is happening here?

Best wishes!
#2
02-25-2011, 04:25 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,462
In the future please insert your code within code tags to preserve the indentation.

I think what you are seeing is that the whole texture quad appears lighted rather than just the small area near the light. Is that correct?

A surface has to be tessellated to have differentiated lighting. So you would need to have many smaller texture quads to get that effect.
#3
03-01-2011, 10:34 AM
 new_horizon Member Join Date: Apr 2010 Posts: 43
Thanks for the reply Jeff - I decided to try to use the Inifinite Terrain and coat it in a tarmac image in order to increase the tesselation...

#Add a texture and set it to repeat mode.
grass.wrap(viz.WRAP_S,viz.REPEAT)
grass.wrap(viz.WRAP_T,viz.REPEAT)

#Add the terrain using the infinte terrain plug-in.
terrain = viz.add('InfiniteTerrain.dlc',1,'456',8,1000,400,1 0000)

#Texture the terrain.
terrain.texture(grass)
terrain.command(1,'',0,0)
terrain.appearance(viz.TEXMODULATE)

However, I am still getting this jagged light effect - almost as if it is passing the light onto one object and then another - just at a faster pace. Is there anyway of smoothing this? Any increase in tesselation value (over 8) for the terrain results in my PC crashing - if an increase is likely to improve this effect, I can find another PC.

Thanks - I appreciate your help!
#4
03-02-2011, 01:47 PM
 Gladsomebeast Member Join Date: Mar 2005 Location: Isla Vizta, CA Posts: 397
For headlights, using the projector plugin will give the best effect. Check out this code and the attached .jpg

Code:
```import viz
viz.go()

import projector

left.border(0.3,0.3,0.3)
left.translate(-1,1.8,0)
left.affect(model)

right.border(0.3,0.3,0.3)
right.translate(1,1.8,0)
right.affect(model,2)

Attached Images
 spotlight.bmp (48.1 KB, 426 views)
__________________
Paul Elliott
WorldViz LLC
#5
03-04-2011, 04:43 AM
 new_horizon Member Join Date: Apr 2010 Posts: 43
Thanks for the reply, I really do appreciate it - that effect is really quite cool, but sadly, it isn't the viewpoint I was looking for.

The basic paradigm here is that I want individuals to make judgements based on the speed at which vehicles are travelling in night-time conditions.

In the attachments, you will see that in Screen Shot 1 - the car appears in full light (although the scene should actually be dark) and in Screen Shot 2, the car appears to be dark (which is correct) - but that is a different issue.

Basically (as Screen Shot 3 demonstrates) as the vehicles are approaching the observation point (they are only visible for 0.75s) the light eminating from the headlights onto the group seems to flicker - as if it is lighting up a particular square and then not the next and then coming back on again.

Is there a way that I can use this plug in here?

Once again, thanks for your time.
Attached Thumbnails

#6
03-04-2011, 10:45 AM
 Gladsomebeast Member Join Date: Mar 2005 Location: Isla Vizta, CA Posts: 397
Instead of linking the projector to the mainview, position it high and point it down.

Code:
```light.setPosition([0, 3, 0])
light.setEuler([0, 90, 0])```
__________________
Paul Elliott
WorldViz LLC

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