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About sjowol

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    Joel Einhorn
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  1. I was looking at the ripple sop and wanted to add some extra noise, I found that you can't just dive inside but it is compiled vex code so I figured it can't be too hard to recreate. Well I got pretty close but for some reason I am missing the high frequency displacement the original ripple has. Attached is an example of the ripple Sop vs my pointvop I guess I'll post the whole code first and then point out where my struggle lies: #include <math.h> #pragma oplabel "Ripple" #pragma opname "ripple" #pragma opicon SOP_ripple #pragma opmininputs 1 #pragma opmaxinputs 1 #define random0(xxx) (random(xxx)*2.0 - 1.0) #pragma label usecenter "Use Center" #pragma label t "Center" #pragma label freq "Frequency" #pragma label height "Height" #pragma label decay "Wave Decay" #pragma label scale "Scale" #pragma label speed "Wave Speed" #pragma label nripples "Num. Ripples" #pragma label seed "Random Seed" #pragma label up "Up Direction" #pragma export freq all #pragma export height all #pragma export nripples all #pragma export decay dialog #pragma export scale dialog #pragma export speed dialog #pragma hint usecenter toggle #pragma hint t vector #pragma hint up vector // Direction vector #pragma disablewhen t { usecenter off } #pragma range nripples 1 10 #pragma range decay 0.01 10 #pragma bindhandle tx xform "Center" tx #pragma bindhandle ty xform "Center" ty #pragma bindhandle tz xform "Center" tz #pragma bindhandle usecenter xform "Center" onoff #pragma bindhandle height ladder "Height" parm0 #pragma bindhandle scale xform "Scale" sx #pragma bindhandle up1 vector "Up" vx invisible(1) #pragma bindhandle up2 vector "Up" vy invisible(1) #pragma bindhandle up3 vector "Up" vz invisible(1) #pragma bindselectorreserved vex_group points "Ripple Points" \ "Select the points for Ripple and press Enter to complete" \ all 0 "" 0 0 1 sop ripple(int usecenter = 0; vector t = {0, 0, 0}; float freq = 1; float height = 0.15; float decay = 0.75; float scale = 1; float speed = 3; int nripples = 3; int seed=0; vector up = {0, 1, 0}; ) { float xc, yc, phase; float dist, len; vector pos; vector origin; vector offset; int i; if (usecenter) { origin = set(scale*random0(seed), scale*random0(seed+1000), 0); offset = t - origin; } else { offset = { 0, 0, 0 }; } for (i = 0; i < nripples; i++) { xc = scale * random0(i+seed); yc = scale * random0(i+(seed+1000)); phase = M_PI * random(i - (seed+1000)); pos = set(xc, yc, 0); pos -= P; pos += offset; len = length(pos); dist = height * exp(-decay*len) * sin(len*(freq*M_PI*2) - Time*speed + phase); P += up * dist; } } I am thinking the high freq noise is coming from the phase and there seems to be a distinction between random0 and random xc and yc are being generated with random0 and phase with random. Also if you look at the code in houdini the random is colored blue (whatever that means.. I always wonder what all the colors mean but I guess that's for another post) This part of the code: xc = scale * random0(i+seed); yc = scale * random0(i+(seed+1000)); phase = M_PI * random(i - (seed+1000)); How do I translate this into VOPs is the big question for me. Thanks in advance!
  2. paticles, shading and transparency

    yeah, that's what i am looking for! thanks for the file my only problem now is that i haven't really done anything in vex yet so don't really get that part (yet). i'll go and ask a tutor maybe they know how to work it (in uni here) could you give me a basic outline of what you've done? thanks a lot! Joel
  3. hi there, at the moment i am working on an effect for my group project in uni, basically it's going to be a sort of hologrammy swirling particle system using filmed footage for the texture. my problem now though... i set up a particle system, thought using sprites would be the best way to go, but you can only shade them seperately, what i want iss to shade my whole particlegroup, so my texture gets projected on the particles (or seems to be projected, i tried doiing it with a simple projection froma light, sort of worked but it should be possible to texture the whole system shouldn't it?) so that's the first main problem, how do i get an orthografic projection that just shades the particle group? then it would be nice if the particles that are farther from the camera would be more transparent then the ones closer to the cam (so getting z-depth and putting that to the transparency) but i can't even seem to find a transparency setting in any of the vex shaders... argh let alone think of a way to get this integrated in my particle system... so if anyone has any idea of how to do this it would be greatly appreciated! cheers, Joel