Houdini Stupid Questions - Revision history

Bernie: /* How do I slide a curve along a curve ? */

2025-11-13T13:39:36Z

How do I slide a curve along a curve ?

← Older revision		Revision as of 15:39, 13 November 2025
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	Jeez I need to sort these		Jeez I need to sort these

			==== How do I transfer attributes without attribtransfer ? ====
			Sometimes attributes transfer just... Doesn't work right. I use good'ole xyzdistprimuv:
			<pre>
			//transfers UVs from source 1 to source 0 using closest surface UV
			i@prim;
			v@uv;
			xyzdist(1, @P, @prim,@uv);
			@uv = primuv(1,"uv",i@prim,@uv);
			</pre>
	==== How do I slide a curve along a curve ? ====		==== How do I slide a curve along a curve ? ====

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	@P = primuv(1,"P",i@prim,@uv);		@P = primuv(1,"P",i@prim,@uv);
	</pre>		</pre>


	==== How can I carve curves with an attribute ? ====		==== How can I carve curves with an attribute ? ====

2025-10-15T16:31:19Z

How do I transform instance points ?

← Older revision		Revision as of 18:31, 15 October 2025
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	===== How do I transform instance points ? =====		===== How do I transform instance points ? =====

			hindsight edit: this feels super cumbersome. If you have packed objects you should simply be able to move,rotate, scale with 'edit'.

	More than once have I had to copy and move around objects manually but felt that simply merging them was a waste of ressources as it could be a simple instance that is moved around.		More than once have I had to copy and move around objects manually but felt that simply merging them was a waste of ressources as it could be a simple instance that is moved around.

2024-08-01T16:09:23Z

How can I carve curves with an attribute ?

← Older revision		Revision as of 18:09, 1 August 2024
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	<pre>		<pre>
	#include <groom.h>		#include <groom.h>
	float newperim = @perimeter*sin(@Time+@primnum/3.0)+1; #notice the 3.0 cause' i'm lazy to cast floats		float newperim = @perimeter*sin(@Time+@primnum/3.0)+1; //notice the 3.0 cause' i'm lazy to cast floats
	adjustPrimLength(0, @primnum, @perimeter, newperim);		adjustPrimLength(0, @primnum, @perimeter, newperim);
	</pre>		</pre>

2024-07-29T12:46:46Z

How can I carve curves with an attribute ?

← Older revision		Revision as of 14:46, 29 July 2024
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	Jeez I need to sort these		Jeez I need to sort these

			==== How do I slide a curve along a curve ? ====

			https://i.imgur.com/t9sm2Uj.gif https://i.imgur.com/ZXdtLOy.jpeg

			Working on snakes ? If you use carve, you'll notice you end up with weird bits where the tips 'pop', what you would like is to slide the curve along another curve, but smoothly. In comes xyzdist and primuv (check out [https://www.toadstorm.com/blog/?p=465 Toadstorm's page]). The advantage is that you will get a real, smooth sliding.

			<pre>
			//input 0 is the carved/small curve
			//input 1 is the full, longer curve

			i@prim;
			v@uv;
			//figure out where i am on the original curve
			xyzdist(1, @P, @prim,@uv);

			//animate the uv.x position, blissfully ignore what happens when we arrive at the end of curve
			@uv.x += (@Time*.1)%1;

			//move along
			@P = primuv(1,"P",i@prim,@uv);
			</pre>


	==== How can I carve curves with an attribute ? ====		==== How can I carve curves with an attribute ? ====

2024-06-03T15:51:54Z

Get the end/start points of primitive curves

@@ Line 4: / Line 4: @@
 Jeez I need to sort these
 ==== Get the end/start points of primitive curves====
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 i@group_end = vertexprimindex(0,@vtxnum) == primvertexcount(0,vertexprim(0,@vtxnum))-1;
 </pre>
 ==== How do I snap objects to objects ====

2024-05-21T15:49:37Z

How do I snap objects to objects

← Older revision		Revision as of 17:49, 21 May 2024
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	Jeez I need to sort these		Jeez I need to sort these

			==== Get the end/start points of primitive curves====
			You can use curveu and fetch 0.0 or 1.0 or use this one-liner
			<pre>
			#in a point wrangle
			i@group_tip = vertexprimindex(0,@vtxnum) == 0;
			i@group_end = vertexprimindex(0,@vtxnum) == primvertexcount(0,vertexprim(0,@vtxnum))-1;
			</pre>
	==== How do I snap objects to objects ====		==== How do I snap objects to objects ====

2024-04-30T16:13:22Z

= How do I snap objects to objects

← Older revision		Revision as of 18:13, 30 April 2024
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	==== How do I snap objects to objects ===		==== How do I snap objects to objects ====

	Works in obj mode, not sop mode, use ';' (Orientatio Picking)		Works in obj mode, not sop mode, use ';' (Orientatio Picking)

2024-04-30T16:13:13Z

Shifting Keyframes in Animation Editor like in Maya

← Older revision		Revision as of 18:13, 30 April 2024
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	=== Shifting Keyframes in Animation Editor like in Maya ===		==== How do I snap objects to objects ===

			Works in obj mode, not sop mode, use ';' (Orientatio Picking)

			Great tutorial here (hipflask) https://www.youtube.com/watch?v=Zh6Q6r9LQlA

			==== Shifting Keyframes in Animation Editor like in Maya ====
	It's a small frustration but to shift frames to later you can write '''+10''' frames		It's a small frustration but to shift frames to later you can write '''+10''' frames
	But if you want to shift frames to an earlier time you have to use '''+-10''' not -10		But if you want to shift frames to an earlier time you have to use '''+-10''' not -10

2024-04-18T10:41:59Z

How do I scale a packed primitive without unpacking it ?

← Older revision		Revision as of 12:41, 18 April 2024
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	Jeez I need to sort these		Jeez I need to sort these

			=== Shifting Keyframes in Animation Editor like in Maya ===
			It's a small frustration but to shift frames to later you can write '''+10''' frames
			But if you want to shift frames to an earlier time you have to use '''+-10''' not -10

			https://i.imgur.com/Dm05N8o.png

	==== How do I scale a packed primitive without unpacking it ? ====		==== How do I scale a packed primitive without unpacking it ? ====

2024-04-15T22:02:02Z

Adding a keyframe to a parameter with python

← Older revision		Revision as of 00:02, 16 April 2024
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	==== Adding a keyframe to a parameter with python ====		==== Adding a keyframe to a parameter with python ====
	You need to create the keyframe, then set it (bind it) to your parm. The doc is kind of mysterious about it but the easiest way to understand how it works it to call the <code>asCode()</code> on your parm.		You need to create the keyframe, then set it (bind it) to your parm. The doc is kind of mysterious about it but the easiest way to understand how it works it to call the <code>asCode()</code> on your parm. I wrote a little snippet to extract code [https://berniebernie.fr/wiki/Houdini_Python#Selected_node_as_python_code here]

	Do that by simply dragging and dropping you parm into a python shell and adding asCode after it like so:		Do that by simply dragging and dropping you parm into a python shell and adding asCode after it like so: