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  #1  
Old 02-25-2011, 09:47 AM
new_horizon new_horizon is offline
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Join Date: Apr 2010
Posts: 43
Headlight Question

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 viztask
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.
viz.MainView.getHeadLight().disable()

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

ball = viz.add('ball.wrl')
ball.appearance(viz.TEXMODULATE)

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

# Create Road
ground = viz.addTexture('tarmac.jpg')
road = viz.addTexQuad(viz.WORLD,viz.MainScene,10) # 100m sq quad
road.texture(ground)
road.setPosition(0,-0.6,0) #
road.rotate(90,90,0)
road.appearance(viz.TEXGEN)
road.appearance(viz.TEXMODULATE)
road2=road.copy()
road2.rotate(90,90,0)
road2.setPosition(0,-0.6,10)

#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)
Radius = 0.1
NUM_DOTS = 10000.0
for i in range(0, NUM_DOTS):
angle= 360.0*(i/NUM_DOTS)
x = Radius*math.sin(angle)
y = Radius*math.cos(angle)
# Put a vertex at each of these, but jump back to zero in between
viz.vertex(0,0)
viz.vertex(x,y)
headlight1 = viz.endlayer()
headlight1.color(1,1,1)
headlight1.setPosition( [ 0 , 0 , -20 ])
#Add a light for the torch.
flash_light = viz.addLight()
#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.spread(80)
#flash_light.spotexponent( 10 )
flash_light.constantattenuation(0)
flash_light.linearattenuation(1)

#flash_light.quadraticattenuation(0)


torch = viz.add('art/flashlight.IVE')
#Link the light source to the torch.
viz.link( headlight1, flash_light)
viz.link( headlight1, torch)

headlight1.setEuler(0,0,0)
headlight1.goto(0,0,15,8, viz.TIME)

#headlight1.addAction( vizact.spin( 10,1,0,90, viz.FOREVER ) )


Can anyone shed any light on what is happening here?

Best wishes!
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  #2  
Old 02-25-2011, 04:25 PM
Jeff Jeff is offline
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Join Date: Aug 2008
Posts: 2,458
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.
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  #3  
Old 03-01-2011, 10:34 AM
new_horizon new_horizon is offline
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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 = viz.add('tarmac.jpg')
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!
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  #4  
Old 03-02-2011, 01:47 PM
Gladsomebeast Gladsomebeast is offline
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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()

model = viz.add('tankmaze.wrl')

import projector

left = projector.add(viz.add('spotlight.bmp'))
left.border(0.3,0.3,0.3)
left.translate(-1,1.8,0)
left.affect(model)

right = projector.add(viz.add('spotlight.bmp'))
right.border(0.3,0.3,0.3)
right.translate(1,1.8,0)
right.affect(model,2)

viz.link(viz.MainView, left)
viz.link(viz.MainView, right)
Attached Images
File Type: bmp spotlight.bmp (48.1 KB, 415 views)
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  #5  
Old 03-04-2011, 04:43 AM
new_horizon new_horizon is offline
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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
Click image for larger version

Name:	NIght Screen Shot 1.JPG
Views:	444
Size:	67.4 KB
ID:	411   Click image for larger version

Name:	NIght Screen Shot 2.JPG
Views:	446
Size:	66.4 KB
ID:	412   Click image for larger version

Name:	Night Screen Shot MC.JPG
Views:	436
Size:	63.1 KB
ID:	413  
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  #6  
Old 03-04-2011, 10:45 AM
Gladsomebeast Gladsomebeast is offline
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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])
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