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gamedesign1
03-31-2016, 10:04 AM
Hi All

This may sound really strange, but I had an idea today which may be stupid or it may have already been done before. I will try to explain.
Cubic projection is really great for boxy shaped objects when there are no gradual curves in the model. But when used on organic shapes you obviously get a seam where the image switches from being projection from one direction to another direction as it goes over a certain angle. I hope that makes sense. What I was thinking is it would be great if we could use the information from where the seam is to create a alpha mask so we could then project another version of the image at say 45 degrees to cover the seam. I know this probably doesn't make sense and I am probably not explaining it very well.

Here are some screenshots to help me explain.

So here is an organic shape with cubic projection. You can see where the seams are when you look at the checkered version.
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Imagine if you had a way to calculate where the path along those seams was and then use that to create a thicker blurred line for a alpha mask.
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You would then be able to project another version of the image that is slightly offset on the projection's rotation to fill in the gap in the alpha mask.


I really hope this makes sense. Please let me know your thoughts, whether it has already been done or if you think its a good idea, or of course if you think its a pointless idea haha.

Would really appreciate your comments :)

ernpchan
03-31-2016, 10:17 AM
You could try making a weight map based on your selected seams. Then use the weight map to blend your different projection modes.

gamedesign1
03-31-2016, 10:20 AM
You could try making a weight map based on your selected seams. Then use the weight map to blend your different projection modes.

Thanks for your reply. The thing is they are not actual seams in geometry they are only seams created by the projected image. Its where a projection switches from a front projection to a top projection for example. Does that make sense?

Snosrap
03-31-2016, 10:28 AM
Yep - this makes sense and it's the reason UV mapping exists. :)

gamedesign1
03-31-2016, 10:30 AM
Yep - this makes sense and it's the reason UV mapping exists. :)

Yeah I know :)
But imagine how quick it would be if you had a node that could calculate that :)

jwiede
03-31-2016, 12:35 PM
Have you tried a spherical projection? In any case, I'm still not quite sure what the node in queston would output? Some definition of the "best" seams? By what projection itself?

gamedesign1
03-31-2016, 01:18 PM
Have you tried a spherical projection? In any case, I'm still not quite sure what the node in queston would output? Some definition of the "best" seams? By what projection itself?

Thanks for your reply :)

No, my idea was for the node to create a mask/gradient based on where the converging projected images meet. So you can use it as a mask. Its so hard to explain haha

Thomas Leitner
04-01-2016, 01:52 AM
....No, my idea was for the node to create a mask/gradient based on where the converging projected images meet. So you can use it as a mask...

Maybe this helps you: you can use the Smoothed Normal of your object to drive a gradient. This gives you a mask of the seam. However, the seam can become very wide, depending on the topology.
Here is a quick and dirty Compound node that does this. Connect the smoothed normal of your object with the Smoothed Normal input of the node.

ciao
Thomas

gamedesign1
04-04-2016, 09:23 PM
Maybe this helps you: you can use the Smoothed Normal of your object to drive a gradient. This gives you a mask of the seam. However, the seam can become very wide, depending on the topology.
Here is a quick and dirty Compound node that does this. Connect the smoothed normal of your object with the Smoothed Normal input of the node.

ciao
Thomas

Thanks I will take a look :)