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  #1  
Old 03-30-2011, 06:18 PM
Zhi Zhi is offline
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Posts: 49
3D grass shader to mimic large grass field

Hi all,

I am new to Vizard. I used Virtools previously. There are some sample compositions in the Virtools forum, using shader to create mimic grass field effect. Some 3d model software, such as the 3ds max, also support online rendering of grass/fur effect. I am curious whether anyone has used shader in Vizard to mimic large field of grass land. Is there any link or script that we can share on this topic?

Thank you.
Zhi
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  #2  
Old 04-02-2011, 01:55 PM
Zhi Zhi is offline
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Never mind. I found a way to use 2D texture to create a wonderul large grass land effect.

Close the thread.
Zhi
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  #3  
Old 04-13-2011, 12:56 AM
JvdBosch JvdBosch is offline
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Quote:
Originally Posted by Zhi View Post
Never mind. I found a way to use 2D texture to create a wonderul large grass land effect.
Please share this with the rest of us. Did you use the shell technique?
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  #4  
Old 04-13-2011, 10:21 AM
Zhi Zhi is offline
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I do not use any shell technique. I simply found a very nice seamless grass texture (as attached) and applied it to the ground. To get rid of the regular pattern due to the repeated tiling of the grass patch (which gives a strong linear perspective cue). I 'blend' the detailed grass ground with a huge noise texture surface. The visual effect of such a grass field looks pretty good, even though it is still 2D textured. Here is the code:

grass = viz.addTexture('Grass.jpg') #Create the detailed grassland with about 100 m in diameter
for x in range(-51, 52, 2):
for z in range(-51, 52, 2):
if (x*x + z*z) < 52*52:
ground = viz.addTexQuad()
ground.setScale([2,2,1])
ground.setPosition([x, 0, z])
ground.setEuler([0, 90, 0])
ground.texture(grass) # Wrap texture on quad

BK = viz.addTexture('Noise.jpg') #Blend the detailed grassland with a low frequency noise map 100 m x 100 m
BKGrnd = viz.addTexQuad()
BKGrnd.setScale([100,100,1])
BKGrnd.setPosition([0, 0, 0])
BKGrnd.setEuler([0, 90, 0])
BKGrnd.texture(BK)
BKGrnd.zoffset(-1)
BKGrnd.alpha(0.2)
Attached Thumbnails
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Name:	Grass.jpg
Views:	25564
Size:	1.05 MB
ID:	416   Click image for larger version

Name:	Noise.JPG
Views:	1998
Size:	768.7 KB
ID:	417  
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  #5  
Old 04-14-2011, 05:05 AM
JvdBosch JvdBosch is offline
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Posts: 36
You can also put the same texture in another map channel and repeat it on a larger scale, possible even rotated.

Code:
                    tex = node.getTexture(unit=0)
                    node.texture(tex,unit=1)
                    node.texblend(0.2,unit=1)
                    trans = viz.Transform()
                    trans.setScale([0.2,0.2,0.2])
                    trans.setAxisAngle(vizmat.EulerToAxisAngle(0,0,45))
                    node.texmat(trans,unit=1)
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  #6  
Old 04-14-2011, 10:35 AM
Zhi Zhi is offline
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Posts: 49
Hi JvdBosch,

What does the trans.setScale([0.2,0.2,0.2]) do. Does it rescale the node or the texture map?

In my code, I have more than 2000 small ground patches (2m x 2m) with the same texture. I have another huge ground patch (100m x 100m) which has a different texture. My question is whether I can blend the two textures as if they were applied to the same node (i.e. the 100m x 100m patch), using the texblend function you suggest?
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