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About markmulli

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  1. Another Expression question :)

    hmm. ok thanks i'll keep trying with it.
  2. Another Expression question :)

    Thanks for taking a look at my problem dante. i changed the "units" in the common tab from secconds to frames and also tried samples but this did not improve the situation. maybe there is something i left out. could you please send me your file? thanks, Mark
  3. Another Expression question :)

    Oops. Made a slight mistake in my last post. The expression was
  4. Hey Guys, I chopl_Expr_wth_lineSop_PntCount.zip
  5. Vops sprites

    I'll have a go at doing it via the sops/pops rout to see if i can get any ideas about bringing it into shaders as i still really want to do this. In regards to the best way to import external values i was trying to import the xyz position of an object in object space not it's points. although for a particle you would be right about using the global variables vop. cheers! Mark
  6. Vops sprites

    haha. i can't believe i didn't see this before! ofcourse i can get the xyz position of any object i desire in vops. just use the parameter sop.. it didn't click at first because i was trying to do all my work from within vops eg looking for some thing that would directly access the object level and get my the parameters i wanted. but all it required was slightly different thinking.. apend a parameter sop to the xyz position of your texture and give the parameter a name. now it apears at the shop level and you can simply channel ref it to any values in houdini :-) however I'd still like to know how to do the particles thing. I'd like to make a pond that ripples whenever particles collide with it's surface. the ripples would need to start from exactly where the particle hit and radiate outward. again. i want to keep the deformation/shading stricktly in shaders. however if you have chops/sops soutions i'm all ears aswell :-) any ideas?
  7. Vops sprites

    hehe no worries.. hey, would you by any chance know how to import the following information into vops? - the XYZ postion of an object in object space. - the XYZ position of all the particles in a particle system. thx Mark
  8. Vops sprites

    hehe, Hey sirogi. I admire you for your persistence with the copy sop! I have tried stamping before but I have to admit I have not tried shader parameter stamping. Sounds awesome.. i will have to check it out when I get back from work tonight. ok now i have to make a few things clear that i should have made clear at the start of this topic.. both those examples are not real projects i am working on. they were simply hypothetical situations and since i want to do this in VOPs i prefer the graffiti example a bit more. To be honest. I am not really looking for the most efficient way to do this in all of Houdini. if i was to do this under a strict budget and timeframe for someone else. than yes, I most defiantly would be looking for the most efficient method in all of Houdini. But right now I am learning VOPs (VOPs addict) and i thought this would be a cool challenge to test the power of VOPs. what i do end up making in the end is undecided. but I
  9. Vops sprites

    hey sirogi " I really don't see why you split VOPS and VEX....they're really the same thing... when you compile a VOPS operator, Houdini is writing the code for you in the background, and compiling it....so there are no places thet VEX can reach that VOPs can't, they're one same thing...." ah. sorry i was not being very clear was i.. i do agree with you. i'm not trying to seperate them. i know that vops is simply a visual interface for vex. however i was thinking that the standard set of vops that come with houdini may not cover the full range of vex functions and to get this full functionality you would need to do some hand coding. (hand coding is what i meant by vex) But who knows.. maybe the visual operators do have ALL the functionality of vex.. i have a lot to learn. I think i will try and track down some of these renderman books you are talking about. as for the copy sop solution. yes i agree the end resault would look fine.. however since it is in geometry and not in my vop network i would loose a lot of control over cetain things. i don't think i could do things easilly like adding a turbulant noise over all the graffiti textures (i know you probably have an answer for that too!) LOL. but seriously. As i have said. i need to do all this with pixels. not polys :-) even if it's just for the challenge of it all.. ps. Anyone had any luck with the loop vops yet? while, for etc? I have read the manual but still can't work out how to use them for something usefull. thanks for all the advice Mark
  10. Vops sprites

    my example of shrubs trees and houses may not have been the best, At first glance I could understand why you might recommend SOPS for this task but I have many other ideas for this that would do well not to use geometry. Ie. I really need to do this within a shading context. picture a long wall with hundreds of different graffiti signatures on it. I would like to create a few decal signatures and scatter them all over the wall within vops, with control over placement, scale, blurriness etc. Of course I can already do this in vops manually with hundreds of texture and mix vops but I am looking for a much simpler more procedural way to solve this. perhaps this is currently too complicated for vex/vops and would require the HDK? sorry if I am sounding a bit confusing but I think something like this could be extremely powerful if it worked. cheers, Mark Ps. I
  11. Vops sprites

    thanks for the tips on the hair. i'll have a play with those ideas tonight. "and the bushes, houses etc... are typically a job for either the copy SOP or one of the instance methods...VOPS are used to build operators (SOPS, SHOPS, COPS...), no to process data...that's the operators' job.." hmm. I'm not sure that this applies to shader vops. unlike geometry VOPs there really is no network for shaders that is higher up than shader vops. the next highest thing is shops but they are not really designed to interact with each other and be wirded up. that's vops job. So i really do think this is a perfectly suitable task for vops shader networks. If it can't be done in vops perhaps i could do it in VEX? anyone? Mark
  12. Vops sprites

    Hey Guys I have a question about the wonderful new VOPs. I thought it would be awesome if there was a way to procedurally scatter a variety of different sprites over a surface? Here is an example of what I am talking about. Let's say you have to make a flight sim game that requires a very large map for the ground. The map needs to have trees, shrubs, huts, and various other objects. The houses would need to be in little community's and aligned to the roads. I know that traditionally this kind of thing would have been done with geometry but I have never seen this kind of thing done in shaders. Basically I need a way to scatter a large variety or pre made sprites over a surface with control over placement scale etc. I guess what I am after is a kind of copy sop in VOPs. I have a feeling that the loop Vops might be in the right direction? Also just a quickie regarding hair, I know there have been a few hair questions on this forum but from memory I think most of them were to do with shading. I'm curious about how the actual hair strands could be made? Could the strands geometry be made with vex? Any suggestions? Thanks Mark