When you say “create a channel on my string parameter”, do you mean create a keyframe on the existing text parameter or something else?
I wasn't using back ticks with python. I just returned to back tick expressions when my python code made things go haywire as per my original post.
Thanks for your idea.
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Houdini Indie and Apprentice » Formatting Time in Font COP
- Len
- 132 posts
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Houdini Indie and Apprentice » Formatting Time in Font COP
- Len
- 132 posts
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I found a solution that will work for me:
Avoiding python entirely, I can use:
`round($T*100)/100`
I still wonder why the python route caused such trouble?
Is it something about using python in a string expression?
Hmm…
Avoiding python entirely, I can use:
`round($T*100)/100`
I still wonder why the python route caused such trouble?
Is it something about using python in a string expression?
Hmm…
Houdini Indie and Apprentice » Formatting Time in Font COP
- Len
- 132 posts
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Hello all.
I've had a heck of a time getting something (apparently) simple to work and would appreciate any pointers:
I'm trying to display the elapsed seconds on my animation using a COP Network.
Using $T in the Text field produces too many significant digits so I was trying to find a way to get, say %3.2f (in sprintf talk). That is, tenth and hundredth places.
My great idea was to use hou.time() in the following:
“%3.2f”%hou.time()
I had a bit of an issue getting this to work at first since I seemed to need a keyframe that didn't exist at first.
But, after adding a keyframe at 1 and using this (along with switching the interpreter to python from hscript) it did work in the viewer.
But..the renders hung on the first frame.
Moving to version 10 seemed to fix this but then certain frames were getting garbled.
I also found that the file would hang upon loading “some” of the time.
In conclusion: Lots of weird issues springing up after adding this font node with that expression. Switched to XP and same issues, more or less.
Any thoughts?
I'm going to just leave it as frames or look for a formatting solution in HScript for now but I really am dismayed to bump into such trouble on such a simple part of my project and not have much of an idea of how to fix it or why it's happening.
The OSX console showed “No Drawable” during the file load hanging.
System: Macbook Pro, Houdini 9.5.379 and 10.0.249.5, Windows XP (32) and OSX (both versions, both OSes).
Thanks!
I've had a heck of a time getting something (apparently) simple to work and would appreciate any pointers:
I'm trying to display the elapsed seconds on my animation using a COP Network.
Using $T in the Text field produces too many significant digits so I was trying to find a way to get, say %3.2f (in sprintf talk). That is, tenth and hundredth places.
My great idea was to use hou.time() in the following:
“%3.2f”%hou.time()
I had a bit of an issue getting this to work at first since I seemed to need a keyframe that didn't exist at first.
But, after adding a keyframe at 1 and using this (along with switching the interpreter to python from hscript) it did work in the viewer.
But..the renders hung on the first frame.
Moving to version 10 seemed to fix this but then certain frames were getting garbled.
I also found that the file would hang upon loading “some” of the time.
In conclusion: Lots of weird issues springing up after adding this font node with that expression. Switched to XP and same issues, more or less.
Any thoughts?
I'm going to just leave it as frames or look for a formatting solution in HScript for now but I really am dismayed to bump into such trouble on such a simple part of my project and not have much of an idea of how to fix it or why it's happening.
The OSX console showed “No Drawable” during the file load hanging.
System: Macbook Pro, Houdini 9.5.379 and 10.0.249.5, Windows XP (32) and OSX (both versions, both OSes).
Thanks!
Technical Discussion » DOPs constraints workflow
- Len
- 132 posts
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Thanks for the idea Axx.
I think I did find a solution that was acceptable that is similar to yours.
Does require a bunch of channel references on a bunch of parameters but in the end seems to work.
Still seems like exploiting parenting somehow would be nice. But I can't see a way.
I think I did find a solution that was acceptable that is similar to yours.
Does require a bunch of channel references on a bunch of parameters but in the end seems to work.
Still seems like exploiting parenting somehow would be nice. But I can't see a way.
Technical Discussion » DOPs constraints workflow
- Len
- 132 posts
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Is there a good way to reposition constraints in DOPs?
I'm trying, in particular, to build a simple car out of a box body and 4 wheels.
I bring each item in as a separate RBD Object to get the best collision surface.
Then I have to create hinge constraints for each wheel.
But now I'd like to go back to the object level and move my top level car to some new starting position.
However, the constraints are set up in world space so they go completely bad at this point. I would need to recalc their location every time I move the car? Is there an easier way? Can I just channel reference the obj transformation from within DOPs?
I'm trying, in particular, to build a simple car out of a box body and 4 wheels.
I bring each item in as a separate RBD Object to get the best collision surface.
Then I have to create hinge constraints for each wheel.
But now I'd like to go back to the object level and move my top level car to some new starting position.
However, the constraints are set up in world space so they go completely bad at this point. I would need to recalc their location every time I move the car? Is there an easier way? Can I just channel reference the obj transformation from within DOPs?
Technical Discussion » Steered Wheel Problem
- Len
- 132 posts
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Hi Kurt.
Yeah, I tried something kind of like that.
I tried creating a goal for the rotate-constrained wheel (using two pin constraints) to another object that would be constrained to only rotate around y and then goaled to the main body.
When I tried that the whole body of the ‘machine’ stopped obeying the groundplane and just sunk into it. Something off about the constraints.
Unfortunately, I think there are subtler things going on with constraints and how they operate in Houdini than I understand right now.
Yeah, I tried something kind of like that.
I tried creating a goal for the rotate-constrained wheel (using two pin constraints) to another object that would be constrained to only rotate around y and then goaled to the main body.
When I tried that the whole body of the ‘machine’ stopped obeying the groundplane and just sunk into it. Something off about the constraints.
Unfortunately, I think there are subtler things going on with constraints and how they operate in Houdini than I understand right now.
Technical Discussion » Steered Wheel Problem
- Len
- 132 posts
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Wow, no takers?
Okay, I'll simplify the problem: How do I make a caster in DOPs? That is, it can rotate like a wheel but then also around that vertical axis that shoves into the chair.
Seems so do-able….in theory…
Okay, I'll simplify the problem: How do I make a caster in DOPs? That is, it can rotate like a wheel but then also around that vertical axis that shoves into the chair.
Seems so do-able….in theory…
Technical Discussion » dopoption and dopfield in Python expressions
- Len
- 132 posts
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Technical Discussion » dopoption and dopfield in Python expressions
- Len
- 132 posts
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Just figured out the last part of my question:
You can embed hscript expressions in python scripts with:
hou.hscriptExpression
Cool!
You can embed hscript expressions in python scripts with:
hou.hscriptExpression
Cool!
Technical Discussion » dopoption and dopfield in Python expressions
- Len
- 132 posts
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Does anyone know how to reproduce the functionality of the dopoption and dopfield functions in Python scripting?
Looking through the help I find hou.dopField.value and hou.dopData.optionRecord as potential replacements but they are listed as ‘unimplemented’ and the rest of the docs don't really clear up the situation for me.
If these are unimplemented, is there a way to invoke dopoption from within a python script?
Thanks!
Looking through the help I find hou.dopField.value and hou.dopData.optionRecord as potential replacements but they are listed as ‘unimplemented’ and the rest of the docs don't really clear up the situation for me.
If these are unimplemented, is there a way to invoke dopoption from within a python script?
Thanks!
Technical Discussion » Steered Wheel Problem
- Len
- 132 posts
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I'm trying to create a dynamic simulation of a simplified vehicle with wheels.
I'm using Hinged constraints to connect spinning wheels to the body, and that works fine, but now can't quite figure out how to actually implement steering on the front wheel.
That is, I'm using a hinge contraint along x for the primary rotation of the wheel but then need to be able to swivel that same wheel about a constant up (y) axis for the steering right and left.
I've played around with various goal configurations but I'm stumped.
It seems like it's got to be a pretty simple system to set up…right?
I've attached a simple Houdini file with my ‘motorcycle’.
Ideally there's one spare channel for steering direction and the solver takes care of the rest.
Any help is appreciated!
File is H9 Apprentice.
I'm using Hinged constraints to connect spinning wheels to the body, and that works fine, but now can't quite figure out how to actually implement steering on the front wheel.
That is, I'm using a hinge contraint along x for the primary rotation of the wheel but then need to be able to swivel that same wheel about a constant up (y) axis for the steering right and left.
I've played around with various goal configurations but I'm stumped.
It seems like it's got to be a pretty simple system to set up…right?
I've attached a simple Houdini file with my ‘motorcycle’.
Ideally there's one spare channel for steering direction and the solver takes care of the rest.
Any help is appreciated!
File is H9 Apprentice.
Technical Discussion » transferring CHOPs data to COPs image
- Len
- 132 posts
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Is there a way to move data from CHOPs back into COPs, if, say, you've processed it there?
In particular, I've got image data converted into channel data via the Image CHOP. I mess with it, now want to save out an image of that data (or at least see what the pixels might look like).
I've seen some discussion of doing a CHOPs-based blur effect but haven't been able to piece it all together.
Thanks for any ideas.
In particular, I've got image data converted into channel data via the Image CHOP. I mess with it, now want to save out an image of that data (or at least see what the pixels might look like).
I've seen some discussion of doing a CHOPs-based blur effect but haven't been able to piece it all together.
Thanks for any ideas.
Technical Discussion » Render COP in Apprentice
- Len
- 132 posts
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Technical Discussion » Render COP in Apprentice
- Len
- 132 posts
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Not a lot of takers, eh? To make it real easy to help me I've attached a super-simple .hipnc test file. It has a torus being rendered, a single Render COP reading from a mantra ROP.
For me, the Render COP will show nothing but the error “File cannot be read”.
I don't get it. What am I doing wrong?
For me, the Render COP will show nothing but the error “File cannot be read”.
I don't get it. What am I doing wrong?
Technical Discussion » Render COP in Apprentice
- Len
- 132 posts
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Thanks for the idea but I specifically want to feedback my renders into COPs, then into CHOPs, then alter some geometry params based on the results.
So I need to use the Render COP as far as I understand it (or the VEX equivalent).
Seems like the Render COP works for someone…?
So I need to use the Render COP as far as I understand it (or the VEX equivalent).
Seems like the Render COP works for someone…?
Technical Discussion » Render COP in Apprentice
- Len
- 132 posts
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Has anyone experienced the same issue as me:
I can't get the Render COP to work in Apprentice.
I point it at an apparently valid Mantra output with .pic format but the Render COP node errors out and it says it can't read the output file.
Does this have something to do with Apprentice only writing out .picnc files and not .pic files?
Or is it me? Or a setting in the Mantra driver I haven't discovered (I've tried a lot)?
If anyone is running Apprentice and can check for me that would be very helpful.
I've searched these forums and can't find a similar issue.
If someone gets this working in Apprentice can you zip and upload a simple file showing it in operation? If you do this you are my idol!
Running: Houdini Master 9.0.794 (Apprentice).
I can't get the Render COP to work in Apprentice.
I point it at an apparently valid Mantra output with .pic format but the Render COP node errors out and it says it can't read the output file.
Does this have something to do with Apprentice only writing out .picnc files and not .pic files?
Or is it me? Or a setting in the Mantra driver I haven't discovered (I've tried a lot)?
If anyone is running Apprentice and can check for me that would be very helpful.
I've searched these forums and can't find a similar issue.
If someone gets this working in Apprentice can you zip and upload a simple file showing it in operation? If you do this you are my idol!
Running: Houdini Master 9.0.794 (Apprentice).
Technical Discussion » Houdini and Machine Vision
- Len
- 132 posts
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Yes! That player/stage stuff is really cool.
Makes me want a robot of my very own!
Simulating one in Houdini will be a start!
Makes me want a robot of my very own!
Simulating one in Houdini will be a start!
Technical Discussion » Houdini and Machine Vision
- Len
- 132 posts
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Thanks for the ideas!
If I had the virtual world to work with I think there are a huge number of interesting games one could play with rays, etc.
Though to truly simulate the robot I'm imagining (with one or more mounted cameras) I think I'd have to force myself to work with a render ROP feeding back in.
I read that section that Caleb wrote (I do have that book) and totally missed that bit where he said he did something like this inside his procedural ‘habitat’.
Very cool.
I should give him a call and hire him!
The whole idea brings up some interesting possibilities with actually simulating robots accurately. Technically, for an accurate test of the robot's ability to survey the environment and make the right maneuver you would need a scene that's as detailed and complex as the real world as possible. Then comes the challenge of actually rendering each frame (full on with texture, complex geometry, lighting etc) to get something as photo-realistic as possible. Then sending this into the robot ‘brain’ to have it analyze and choose its next move. If your images are good enough, it seems like you'd start to approach a valid test scenario. Could be very useful if your actual testing environment was too difficult or expensive to work in (like the deck of an aircraft carrier, say). I wonder if anyone has been doing that sort of robotic simulation?…Interesting.
If I had the virtual world to work with I think there are a huge number of interesting games one could play with rays, etc.
Though to truly simulate the robot I'm imagining (with one or more mounted cameras) I think I'd have to force myself to work with a render ROP feeding back in.
I read that section that Caleb wrote (I do have that book) and totally missed that bit where he said he did something like this inside his procedural ‘habitat’.
Very cool.
I should give him a call and hire him!
The whole idea brings up some interesting possibilities with actually simulating robots accurately. Technically, for an accurate test of the robot's ability to survey the environment and make the right maneuver you would need a scene that's as detailed and complex as the real world as possible. Then comes the challenge of actually rendering each frame (full on with texture, complex geometry, lighting etc) to get something as photo-realistic as possible. Then sending this into the robot ‘brain’ to have it analyze and choose its next move. If your images are good enough, it seems like you'd start to approach a valid test scenario. Could be very useful if your actual testing environment was too difficult or expensive to work in (like the deck of an aircraft carrier, say). I wonder if anyone has been doing that sort of robotic simulation?…Interesting.
Technical Discussion » Houdini and Machine Vision
- Len
- 132 posts
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Technical Discussion » Houdini and Machine Vision
- Len
- 132 posts
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Aha! You're quite right. Going all the way to render and dealing with a 2d image may not be the way to go.
However, say you are trying to prototype robot algorithms in Houdini.
That is, you are ultimately going to build the actual robot that you've built out of a few cones and cylinders in Houdini.
So that “actual” robot will only have a ‘rendered’ view, if you will, of the scene in front of it through its on-board camera ‘eye’.
I think that's the key distinction of what I'm attempting here. I don't want to just create certain behavior (like flocking or your very cool YouTube video).
I need to simulate an actual robot interacting with an actual world by using virtual stand-ins.
Make sense?
So, if that's the case…how best to start? Is it even possible?
If not in Houdini, custom code the way to go?
However, say you are trying to prototype robot algorithms in Houdini.
That is, you are ultimately going to build the actual robot that you've built out of a few cones and cylinders in Houdini.
So that “actual” robot will only have a ‘rendered’ view, if you will, of the scene in front of it through its on-board camera ‘eye’.
I think that's the key distinction of what I'm attempting here. I don't want to just create certain behavior (like flocking or your very cool YouTube video).
I need to simulate an actual robot interacting with an actual world by using virtual stand-ins.
Make sense?
So, if that's the case…how best to start? Is it even possible?
If not in Houdini, custom code the way to go?
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