I am really getting into scripting now that I am using Linux on a daily basis. I am curious about Houdini's pre and post render scripts and I am wondering how far you can go with it and what can be done with them.
Can anybody provide some examples of what you can do with pre and post render scripts and how they improve the render workflow? Thanx!
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Technical Discussion » examples of pre and post render scripts
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- vrljc
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Houdini Lounge » Hoo-ray! fer fancy book learnin'
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- vrljc
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Yes, I did the FX on the cover. I am glad you liked the short film. The crew of us who worked on the cover are honored to be able to supply the image, as we are all GREATLY looking forward to getting our hands on a copy of the book.
Its kinda funny with Houdini that just when you think you know the package, you can always find a new area to dive deeper into. I hope I can do that some more using the material in the book.
Its kinda funny with Houdini that just when you think you know the package, you can always find a new area to dive deeper into. I hope I can do that some more using the material in the book.
Houdini Lounge » Hoo-ray! fer fancy book learnin'
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- vrljc
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Technical Discussion » customizing handles in a dig asset
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- vrljc
- 63 posts
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Sorry, I meant digital asset, such as a custom OTL. Basically my otl lets the user move vertices around (there are about 10), so I wanted to have the origin of the handle for each vertice to be snapped to the vertice, and not show up @ the center of the otl.
If this can be done by changing the pivot, how do you go about this?
If this can be done by changing the pivot, how do you go about this?
Technical Discussion » customizing handles in a dig asset
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- vrljc
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Just curious if it is possible to move the origin of a handle on a dig asset? So that it is not centered?
Any ideas?
Any ideas?
Technical Discussion » Call Back scripts with Menu Items in Otl
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- vrljc
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Technical Discussion » Call Back scripts with Menu Items in Otl
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- vrljc
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Ok I am def going in the right direction now, but I am having some syntax issues I think. So far my script looks like this:
if(“ch(”display“)” == “0”)
then
message `on`
else
message `off`
endif
So this says that if I have Item#1 selected from the pulldown menu, it should return a message saying “on” and it should say “off” if #2 is selected. Well what is happening is that no matter which item i have selected, it is only returning “off.”
As a test that it is indeed finding ch(“display”), I added to the bottom:
message `ch(“display”)`
And it returned the correct 0 or 1. I guess I am just not writing the if/then/else statement correctly?
if(“ch(”display“)” == “0”)
then
message `on`
else
message `off`
endif
So this says that if I have Item#1 selected from the pulldown menu, it should return a message saying “on” and it should say “off” if #2 is selected. Well what is happening is that no matter which item i have selected, it is only returning “off.”
As a test that it is indeed finding ch(“display”), I added to the bottom:
message `ch(“display”)`
And it returned the correct 0 or 1. I guess I am just not writing the if/then/else statement correctly?
Technical Discussion » Call Back scripts with Menu Items in Otl
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- vrljc
- 63 posts
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How can I trigger a specific callback script based upon which item is selected from a Menu Item? For example, if Item#1 in the Menu is selected, it will trigger this callback script:
viewdisplay -N all l on *; viewdisplay -N all n on *; viewdisplay -N all m on *;
Then when I select Item#2, it will trigger this callback script:
viewdisplay -N all l off *; viewdisplay -N all n off *; viewdisplay -N all m off *;
Any ideas?
viewdisplay -N all l on *; viewdisplay -N all n on *; viewdisplay -N all m on *;
Then when I select Item#2, it will trigger this callback script:
viewdisplay -N all l off *; viewdisplay -N all n off *; viewdisplay -N all m off *;
Any ideas?
Technical Discussion » trouble with Takes, rendering
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- vrljc
- 63 posts
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I got the take to work now. Turned out I really didnt know what I was doing in the first place 
But now I understand takes fully. I understand a take as a different variation of the same hip file, where you can turn things on and off, yet jump back and forth to another version of the hip.
Peter, can you explain a bit more about VOPs not working with takes? As a test I built a simple VOP surface shader and it worked fine with a take. Are you referring to a more complicated VOP such as a SOP or POP VOP?
-jon
But now I understand takes fully. I understand a take as a different variation of the same hip file, where you can turn things on and off, yet jump back and forth to another version of the hip.Peter, can you explain a bit more about VOPs not working with takes? As a test I built a simple VOP surface shader and it worked fine with a take. Are you referring to a more complicated VOP such as a SOP or POP VOP?
-jon
Technical Discussion » trouble with Takes, rendering
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- vrljc
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I am having some trouble getting a take to render. I created a take and called it “shadow” so that I can render a shadow pass. Everything in the take is all set to do just that (i.e. turned off objects/enabled shaders, etc).
In my mantra ROP in the pre-script i entered in the code
takeset shadow
Then in the post-script i entered in
takeset hip
to put everthing back in place.
But what is happening is that the ROP is rendering out a full render, and not occluding or including objects as I set them to do in the take panel. Is there a step that I missed in the process of setting up a take?
-jon
In my mantra ROP in the pre-script i entered in the code
takeset shadow
Then in the post-script i entered in
takeset hip
to put everthing back in place.
But what is happening is that the ROP is rendering out a full render, and not occluding or including objects as I set them to do in the take panel. Is there a step that I missed in the process of setting up a take?
-jon
Houdini Lounge » student short film with some houdini FX
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- vrljc
- 63 posts
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Hi Everyone-
A group of us just finished a short student animated film, “The Potter,” that we have been working on for about a year now.
I had the opportunity to use Houdini in my role as the FX guy on the team. This is the first time I have actually been able to use Houdini in a production and it definately paid off. Here is a link to the film:
http://studentpages.scad.edu/~jburto21/potter/The_Potter_480x270.mov [studentpages.scad.edu]
Everytime you see either a sparkly pixi dust effect, or volumetric breath effect, or bright glowy globs, that was Houdini at work.
Enjoy!
-jon campbell
A group of us just finished a short student animated film, “The Potter,” that we have been working on for about a year now.
I had the opportunity to use Houdini in my role as the FX guy on the team. This is the first time I have actually been able to use Houdini in a production and it definately paid off. Here is a link to the film:
http://studentpages.scad.edu/~jburto21/potter/The_Potter_480x270.mov [studentpages.scad.edu]
Everytime you see either a sparkly pixi dust effect, or volumetric breath effect, or bright glowy globs, that was Houdini at work.
Enjoy!
-jon campbell
Houdini Lounge » Gimbal Lock, what is it?
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- vrljc
- 63 posts
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Technical Discussion » pscale, ramping up and down
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- vrljc
- 63 posts
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Yes, that is where it can be entered. Depending on what you prefer, you can either enter it at the pop level, or you can append a point sop after your popmerge sop and enter it there, but you still need to add a property pop. So I just save a step and do it at the POP level.
It does create a smooth ramping effect when getting bigger. Based upon the expression, a particle's scale is the same value as its age, until it hits $AGE==1. Because of the clamp, it will stay at one and grow no larger or smaller, until later on in the expression when the second “if” statement appears. it tells the particle to start shrinking back down to 0: (5-$AGE). As for the 1 in the false return, I just did it to be safe. Regardless, it works.
Understand now?
-jon
It does create a smooth ramping effect when getting bigger. Based upon the expression, a particle's scale is the same value as its age, until it hits $AGE==1. Because of the clamp, it will stay at one and grow no larger or smaller, until later on in the expression when the second “if” statement appears. it tells the particle to start shrinking back down to 0: (5-$AGE). As for the 1 in the false return, I just did it to be safe. Regardless, it works.
Understand now?
-jon
Technical Discussion » zdepth shader using vops?
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- vrljc
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Is it possible to create a zdepth shader using VOPs that can be applied as a surface shader to a piece of geometry and then rendered as an image render in place of a zdepth deep raster render?
I did this before where I created a surface position shader and applied it and rendered it, and it came out the same as a surface position deep raster render.
Is this possible?
-jon
I did this before where I created a surface position shader and applied it and rendered it, and it came out the same as a surface position deep raster render.
Is this possible?
-jon
Technical Discussion » pscale, ramping up and down
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- vrljc
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I figured it out:
if($AGE>=0 && $AGE <=1,clamp($AGE,0,1), if($AGE>=4 && $AGE<=5,5-$AGE,1))
Once I remembered the difference between $AGE and $LIFE, it clicked.
-jon
if($AGE>=0 && $AGE <=1,clamp($AGE,0,1), if($AGE>=4 && $AGE<=5,5-$AGE,1))
Once I remembered the difference between $AGE and $LIFE, it clicked.
-jon
Technical Discussion » pscale, ramping up and down
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- vrljc
- 63 posts
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Whoops! I forgot that $LIFE is always a value between 0 and 1. What I meant in my question is $AGE. Here it is corrected:
I am shooting out some particles and they all have a lifespan of 5 seconds (24fps). I am trying to make the particles' pscale start at 0 at $AGE==0, then grow to 1 by the time $AGE==1. Then the pscale will remain at 1 until $AGE==4, where the pscale will then start to shrink back down to 0 by $AGE==5, or death.
-jon
I am shooting out some particles and they all have a lifespan of 5 seconds (24fps). I am trying to make the particles' pscale start at 0 at $AGE==0, then grow to 1 by the time $AGE==1. Then the pscale will remain at 1 until $AGE==4, where the pscale will then start to shrink back down to 0 by $AGE==5, or death.
-jon
Technical Discussion » pscale, ramping up and down
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- vrljc
- 63 posts
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I have a pscale problem I am trying to figure out. Here is my situation and what I want to do.
I am shooting out some particles and they all have a lifespan of 5 seconds (24fps). I am trying to make the particles' pscale start at 0 at $LIFE==0, then grow to 1 by the time $LIFE==1. Then the pscale will remain at 1 until $LIFE==4, where the pscale will then start to shrink back down to 0 by $LIFE==5, or death.
Can anyone help me figure out this pscale expression?
-jon
I am shooting out some particles and they all have a lifespan of 5 seconds (24fps). I am trying to make the particles' pscale start at 0 at $LIFE==0, then grow to 1 by the time $LIFE==1. Then the pscale will remain at 1 until $LIFE==4, where the pscale will then start to shrink back down to 0 by $LIFE==5, or death.
Can anyone help me figure out this pscale expression?
-jon
Technical Discussion » deep raster: surface position render problem
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- vrljc
- 63 posts
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Simon, thanx for the tip. I will try that out next time.
J.C., I actually got it to render out as a 32 bit tiff; I just made sure i hit the little down arrow next to the Tiff box and selected 32 bit floating….thanx though!
-jon
J.C., I actually got it to render out as a 32 bit tiff; I just made sure i hit the little down arrow next to the Tiff box and selected 32 bit floating….thanx though!
-jon
Technical Discussion » deep raster: surface position render problem
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- vrljc
- 63 posts
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J.C.-
Thanks for the reply. I think I have been going about this all wrong. Can you tell me if this approach will work, even though it is a one pass render?
In VOPS, i created a vex surface shader. Inside, I just added a global variable vop, then piped its surface position into the output vop's Cf. Then I applied this new vex shader to the object that is being rendered.
Then I nixed the deep raster render, and rendered out the new surface position pass as a basic mantra render. The results looks very similar (if not the same) to the old (unsuccessful) deep raster render.
Did I just render out a correct surface position pass?
-jon
Thanks for the reply. I think I have been going about this all wrong. Can you tell me if this approach will work, even though it is a one pass render?
In VOPS, i created a vex surface shader. Inside, I just added a global variable vop, then piped its surface position into the output vop's Cf. Then I applied this new vex shader to the object that is being rendered.
Then I nixed the deep raster render, and rendered out the new surface position pass as a basic mantra render. The results looks very similar (if not the same) to the old (unsuccessful) deep raster render.
Did I just render out a correct surface position pass?
-jon
Technical Discussion » deep raster: surface position render problem
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- vrljc
- 63 posts
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Hello-
I am doing a surface position deep raster render. I am having a problem. The problem is that all of a sudden the deep raster render will just stop, giving me a red flag error on the mantra. The error message states:
“Could not write out to the script or pipe. Failed to complete render”
But if I reset the frame range to start after the bad render, the render will continue again, until about 20 frames later it stops again, giving me the same error. And this will repeat.
Any help would be appreciated.
-jon
I am doing a surface position deep raster render. I am having a problem. The problem is that all of a sudden the deep raster render will just stop, giving me a red flag error on the mantra. The error message states:
“Could not write out to the script or pipe. Failed to complete render”
But if I reset the frame range to start after the bad render, the render will continue again, until about 20 frames later it stops again, giving me the same error. And this will repeat.
Any help would be appreciated.
-jon
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