JayT Posted May 11, 2008 Share Posted May 11, 2008 Hi! Im new to the forum and am currently learning Houdini. I have created an effect in VEX where a piece of geometry gets distorted by particles colliding into it. My VOP has two inputs, the first for the geometry (say a grid) and the second for the particles. Inside the VOP I have managed to create expressions to distort the geometry where the particle has hit the surface. Now I want to use the life/age of the particles to control how long the distortion lasts for. The problem comes in when I try to grab the particles life attribute. I create an 'import attribute' node, then in the parameters I set Signature to 'float attribute', type 'life' into Attribute and set OP Input Index to 1 (the second input of the VOP which should be the particles). Theoretically this should give me the life of the particle which I can then use to reduce the distortion over time and eventually stop when the particle dies. However this doesn't seem to be the case and the imported attribute gives me random values. I have tried changing the attribute to 'age', copying the attribute and pasting the reference and even tried lower/upper case letters. But it doesn't give me anything useful I can use. Can anyone help me with what I am doing wrong or give me other ideas on how to fade away my effect dependant on the particles? Thanks Quote Link to comment Share on other sites More sharing options...
sibarrick Posted May 11, 2008 Share Posted May 11, 2008 How do you decide which point number to import the attribute from on the second input? That might be the source of your trouble. You can't just pass it the point being process in the first input. Quote Link to comment Share on other sites More sharing options...
stevenong Posted May 11, 2008 Share Posted May 11, 2008 Hi, I'm not providing any answer but an alternative to implementing what you want. Here's the pointcloud presentation on the SESI Exchange which has an example of what you want to do. Cheers! steven Quote Link to comment Share on other sites More sharing options...
tjeeds Posted November 28, 2008 Share Posted November 28, 2008 Just saw this question, I'm sure you've figured this out by now but for others searching on this I believe the answer lies in that fact that $LIFE is not the same as the attribute "life". When you pull up Details view on your particles you'll see life(0) and life(1) listed. life(0) is how many seconds the particle has been alive, life(1) is how many seconds the particle will live. $AGE is the variable that references life(0), but $LIFE actually references life(0)/life(1) giving you a 0 to 1 value. I've not been able to import life(0) or life(1) into a vop but before the VOP POP you can lay down an Attribute POP and use $LIFE as the value. This attribute can then be imported into your VOP. Quote Link to comment Share on other sites More sharing options...
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