Liuzkai/Houdini
https://github.com/Liuzkai/Houdini/blob/master/VEXpressions.txt
- # Lines starting with # are comments and ignored
- #
- # Each entry starts with no indentation and gives the key used
- # by the menu callback. By convention, this is nodename/parmname.
- # Multiply keys can be given for the same entry.
- #
- # The next line gives the name of the expression. Its indentation
- # level is then used for the remainder of the text. All the
- # code until the next parameter are appended together to make
- # the snippet. All preceeding indentation is removed.
- # Note that tabs == 8 is assumed.
- #
- # POPs
- #
- popfan/localexpression
- Pass Through
- // Center:
- t = t;
- // Cone angle:
- cone = cone;
- dir = dir;
- windspeed = windspeed;
- airresist = airresist;
- popfan/localexpression
- Randomize Airresist by Id
- airresist *= rand(@id);
- popfilamentforce/localexpression
- Pass Through
- velscale = velscale;
- airresist = airresist;
- forcescale = forcescale;
- velblend = velblend;
- popfilamentforce/localexpression
- Randomize by Id
- airresist *= rand(@id);
- forcescale *= rand(@id);
- popforce/localforceexpression
- Randomize Magnitude
- // Assign to a float to force rand to scalar.
- // 0.5 and 1.0 are the min and max scales
- float amt = rand(@id);
- force *= fit01(amt, 0.5, 1.0);
- popforce/localforceexpression
- Orbit the Origin
- // length(force) ensures the parameter
- // still has an effect on the scale of
- // the orbit
- vector axis = { 0, 1, 0 };
- vector center = { 0, 0, 0 };
- force = length(force) * cross(@P-center, axis);
- popforce/localforceexpression
- Force Until Velocity Reached
- float threshold = 2.0; // Cut off
- float speed = length(@v);
-
- if (speed > threshold)
- {
- force = 0;
- }
- popforce/localforceexpression
- Scale Force According to Proximity to Point
- vector pos = { 0, 2, 0 }; // Point Position
- float radius = 1.0; // Radius of effect
- float dist = length(@P - pos);
- dist /= radius; // Normalize distance
- //force *= 1 - clamp(dist, 0, 1); // simple linear force
- force *= smooth(0, 1, 1-dist); // reversed ease in-out force
- popforce/localnoiseexpression
- popwind/localnoiseexpression
- Amplitude by Age
- // Ease in using age in seconds
- amp *= smooth(0, 1.5, @age);
- popforce/localnoiseexpression
- popwind/localnoiseexpression
- Amplitude by Normalized Age
- // Ease in based on percentage life
- amp *= smooth(0, 0.2, @nage);
- popforce/localnoiseexpression
- popwind/localnoiseexpression
- Amplitude by Speed
- // speed determines amplitude of effect
- float min = 0.5; // minimum speed threshold
- float max = 1.0; // maximum speed threshold
- float width = 0.1; // ease in and out feather width
- float vmag = clamp(length(@v), min, max);
- amp *= smooth(min, min + width, vmag) - smooth(max - width, max, vmag);
- popforce/localnoiseexpression
- popwind/localnoiseexpression
- Scale by Velocity
- // boost noise for lower velocity values
- amp *= fit(length(@v), 0, 0.5, 2, 1);
- popdrag/localdragexpression
- Drag by Proximity to Point
- vector target = {0, 1, 0}; // Target position
- float dist = length(@P - target); // distance to target
- float radius = 2.0; // Effect radius
- dist = fit(dist, 0, radius, 0, 1); // fit to range
- airresist *= dist;
- popdragspin/localdragexpression
- Drag by Proximity to Point
- vector target = {0, 1, 0}; // Target position
- float dist = length(@P - target); // distance to target
- float radius = 2.0; // Effect radius
- dist = fit(dist, 0, radius, 0, 1); // fit to range
- spinresist *= dist;
- popattract/goalcode
- Spread Goal
- float spread = 0.1;
- float seed = 0.1245;
- goal += spread * (vector(rand(@id+seed)) - 0.5);
- popattract/forcecode
- Randomize Force Scale
- float fmin = 0.1;
- float fmax = 1.0;
- forcescale *= fit01( rand(@id), fmin, fmax );
- popcolor/localconstant
- Color by Velocity Magnitude
- // Color red by velocity magnitude
- float vmax = 1.0;
- color = set(fit(length(@v), 0, vmax, 0, 1), 0, 0);
- popcolor/localconstant
- Color by Condition
- // Condition is Position Y greater than 1.
- // Use any attribute test you wish.
- if (@P.y > 1.0)
- {
- color = color; // Set to parameter value
- }
- else
- {
- color = @Cd; // Restore
- }
- popcolor/localconstant
- Color by Proximity
- vector center = {0,1,0};
- float radius = 2.0;
- color = fit(length(@P - center), 0, radius, 1, 0); // reverse fit index
- popinstance/localexpression
- Random Scale
- // Note you have to turn on the pscale option for this
- // to work!
- pscale *= rand(@id);
- popkill/rulecode
- Kill by Condition
- dead = (@P.y > 1) ? 1 : 0;
- poplocalforce/localforce
- Randomize Thrust, Lift and Side Slip
- float seed = 0.12345;
- thrust *= fit01(rand(@id+seed), 0.5, 1);
- lift *= fit01(rand(@id+seed+0.1), 0.5, 1);
- sideslip *= fit01(rand(@id+seed+0.2), 0.5, 1);
- poplookat/code
- Orient to Velocity
- // Force mode to target is direction:
- mode = 1;
- target = @v;
- popproperty/localexpression
- Randomize Mass
- float seed = 0.12345;
- mass *= fit01(rand(@id+seed), 0.7, 1);
- popproperty/localexpression
- Randomize Particle Scale
- float seed = 0.12345;
- pscale *= fit01(rand(@id+seed), 0.5, 1.5);
- popspeedlimit/localexpression
- Randomize Speed and Spin
- float seed = 0.12345;
- speedmin *= fit01(rand(@id+seed), 0.5, 1);
- speedmax *= fit01(rand(@id+seed+.1), 0.5, 1);
- spinmin *= fit01(rand(@id+seed+.2), 0.5, 1);
- spinmax *= fit01(rand(@id+seed+.3), 0.5, 1);
- popvelocity/localexpression
- Pass Through
- scale = scale;
- v = v;
- popvelocity/localexpression
- Scale Velocity
- v = @v * scale;
- popvelocity/localexpression
- Project onto Vector
- vector nv = normalize(v);
- v = dot(nv, @v) * nv;
- popvelocity/localexpression
- Project onto Plane
- vector nv = normalize(v);
- v = @v - dot(nv, @v) * nv;
- popvelocity/localexpression
- Set Speed
- // The implicit multiplication by scale will
- // then set the speed.
- v = normalize(@v);
- popspin/localexpression
- Pass Through
- // oldspinspeed also exists giving the
- // previous spin in degrees per second
- spinspeed = spinspeed;
- axis = axis;
- popspin/localexpression
- Scale Spin Speed
- // We treat the spinspeed as a scale here
- // and ignore the axis.
- axis = @w;
- spinspeed = oldspinspeed * spinspeed;
- popspin/localexpression
- Project onto Vector
- vector naxis = normalize(axis);
- axis = dot(naxis, @w) * naxis;
- // Construct the required spinspeed
- spinspeed = degrees( length(axis) );
- popspin/localexpression
- Rotate onto Vector
- vector naxis = normalize(axis);
- axis = dot(naxis, @w) * naxis;
- spinspeed = oldspinspeed;
- popspin/localexpression
- Project onto Plane
- vector naxis = normalize(axis);
- axis = @w - dot(naxis, @w) * naxis;
- // Construct the required spinspeed
- spinspeed = degrees( length(axis) );
- popspin/localexpression
- Rotate onto Plane
- vector naxis = normalize(axis);
- axis = @w - dot(naxis, @w) * naxis;
- spinspeed = oldspinspeed;
- popspin/localexpression
- Set Spin Speed
- // The implicit multiplication by spinspeed will
- // then set the speed.
- axis = @w;
- #
- # Point Wrangle
- #
- attribwrangle/snippet
- Add Value to Y Position
- @P += {0,1,0};
- attribwrangle/snippet
- Flatten Points in Y
- @P = set(@P.x, 0, @P.z);
- attribwrangle/snippet
- Add Random to Y Position:
- @P += set(@P.x, rand(@ptnum), @P.z);
- attribwrangle/snippet
- Velocity from Surface Normals
- @v = @N; // v from surface normals
- attribwrangle/snippet
- Color from Bounding Box
- @Cd = relbbox(0, @P);
- attribwrangle/snippet
- Flared Y Velocity Attributes
- float vely = 1.0; // Velocity in Y
- vector offset = {0, 0, 0}; // Offset flare center
- float seed = 0.12345; // seed for rand
- float randamt = 0.1; // amount of randomness to add
- vector bbox = relbbox(0, P); // bounding box of point
- bbox += offset; // transform bbox by offset
- @v = set(bbox.x, vely, bbox.z); // set v
- @v += rand(seed+@ptnum)*randamt; // add noise to v
- attribwrangle/snippet
- Percent pscale Along Curve:
- @pscale = @ptnum/(@Npt-1.0); // initialize pscale
- //@pscale = spline("catmull-rom", index, 0,0,0.25,0.3,1,1);
- attribwrangle/snippet
- Normalize Surface Normals
- @N = normalize(@N); // normalize surface normals
- attribwrangle/snippet
- Random Point Color:
- float seed = 0.12345; // seed for rand
- @Cd = rand(seed + @ptnum);
- attribwrangle/snippet
- Random Y Velocity
- float seed = 0.12345; // initialize seed
- @v = set(0, rand(@ptnum+seed), 0); // random velocity in Y
- attribwrangle/snippet
- Simple Noise to Y Position
- @P = set(@P.x, @P.y + fit01(noise(@P),-1, 1)*0.5, @P.z);
- attribwrangle/snippet
- Add Noise to Position
- float amp = 1; // amplitude of noise
- float time = Time * 0.5; // speed time used in offset
- int seed = 1; // seed of noise
- int octaves = 1; // octaves for turbulence noise
- vector freq = {1,1,1}; // noise frequency
- vector offset = set(0, time, 0); // animate offset with time in Y
- vector pos = ptransform("space:current", "space:world", @P);
- // uncomment the noise function below you want to use
- @P += noise(pos * freq + offset + seed) * amp;
- //@P += onoise(pos * freq + offset + seed) * amp;
- //@P += hscript_noise(pos * freq + offset + seed) * amp;
- //@P += hscript_rand(pos * freq + offset + seed) * amp;
- //@P += hscript_turb(pos * freq + offset + seed, octaves) * amp;
- //@P += hscript_sturb(pos * freq + offset + seed, octaves) * amp;
- attribwrangle/snippet
- Swap Point Position with Rest
- vector tmp = @P;
- @P = @rest;
- @rest = tmp;
- attribwrangle/snippet
- Swap Point Position with UV
- vector tmp = @P;
- @P = @uv;
- @uv = tmp;
- attribwrangle/snippet
- Color Based on Threshold
- int condition = (@P.x > 0) ? 1 : 0; // short form if() test
- @Cd = set(condition, 0, 0); // write condition into red color
- attribwrangle/snippet
- Point Group on Threshold
- string group = "mygroup"; // group name to add points to
- int condition = (@P.x > 0) ? 1: 0; // short form if() test
- if (condition)
- addgroup(group, @ptnum); // if true add point to group
- @Cd = set( condition, 0, 0); // color if in group
- attribwrangle/snippet
- Fetch Second Input Position
- // Second input used as reference geometry
- @P = point(1, "P", @ptnum); // set second input position to first
- attribwrangle/snippet
- Fetch Second Input Cd Attribute
- // Second input used as reference geometry
- @Cd = point(1, "Cd", @ptnum);
- attribwrangle/snippet
- Fetch Second Input Attribute by id
- // grab attribute by id match from second input
- // id attribute present on both inputs for indexing
- int match_pt = findattribval(1, "point", "id", @id); // matching point
- @P = point(1, "P", match_pt); // use matching point to fetch attribute
- attribwrangle/snippet
- Nearest Point Distance
- // Second input used for reference geometry
- int closept = nearpoint(1, @P); // get point number of near point
- vector value = point(1, "P", closept);// get position of near point
- @dist = length(@P - value); // export distance from nearest point
- @Cd = set(@dist, 0, 0);
- #
- # Attribute Wrangle
- #
- attribwrangle/snippet
- Color from Bounding Box
- @Cd = relbbox(0, @P);
- attribwrangle/snippet
- Random Point Color:
- float seed = 0.12345; // seed for rand
- @Cd = rand(seed + @ptnum);
- attribwrangle/snippet
- Color Based on Threshold
- int condition = (@P.x > 0) ? 1 : 0; // short form if() test
- @Cd = set(condition, 0, 0); // write condition into red color
- attribwrangle/snippet
- Point Group on Threshold
- string group = "mygroup"; // group name to add points to
- int condition = (@P.x > 0) ? 1: 0; // short form if() test
- setpointgroup(geoself(), group, @ptnum, condition);
- @Cd = set( condition, 0, 0); // color if in group
- attribwrangle/snippet
- Fetch Second Input Cd Attribute
- // Second input used as reference geometry
- // Use prim and @primnum to get a matching primitive attribute.
- @Cd = point(1, "Cd", @ptnum);
- attribwrangle/snippet
- Fetch Second Input Attribute by id/name
- // grab attribute by id match from second input
- // id attribute present on both inputs for indexing
- int match_pt = findattribval(1, "point", "id", @id); // matching point
- @P = point(1, "P", match_pt); // use matching point to fetch attribute
- // grab attribute by name attribute
- // int match_prim = findattribval(1, "prim", "name", @name); // matching name
- // @Cd = prim(1, "Cd", match_prim);
- attribwrangle/snippet
- Nearest Point Distance
- // Second input used for reference geometry
- int closept = nearpoint(1, @P); // get point number of near point
- vector value = point(1, "P", closept);// get position of near point
- @dist = length(@P - value); // export distance from nearest point
- @Cd = set(@dist, 0, 0);
- attribwrangle/snippet
- Grow Hairs
- vector dir = { 0, 1, 0 };
- // dir = @N; // grow in normal direction
- float len = 1.0;
- int steps = 10;
- float jitter = 0.1;
- float seed = 0.12345;
- vector pos = @P;
- int pr = addprim(geoself(), "polyline");
- // Start the curve with our point
- addvertex(geoself(), pr, @ptnum);
- for (int i = 0; i < steps; i++)
- {
- pos += dir * len / steps;
- pos += (vector(rand( @ptnum + seed )) - 0.5) * jitter;
- // Clone our point to copy attributes
- int pt = addpoint(geoself(), @ptnum);
- // But write a new position
- setpointattrib(geoself(), "P", pt, pos);
- // Connect the new point to our curve.
- addvertex(geoself(), pr, pt);
- seed += $PI;
- }
- attribwrangle/snippet
- Get Neighbouring Points into Attribute
- i[]@neighbours = neighbours(0, @ptnum);
- attribwrangle/snippet
- Average Neighbouring Points
- int n[] = neighbours(0, @ptnum);
- vector avgP = @P;
- // Loops over all elements of n, setting pt
- // to be the value of each element
- foreach (int pt; n)
- {
- avgP += point(0, "P", pt);
- }
- // +1 because we included ourself.
- avgP /= len(n)+1;
- @P = avgP;
- #
- # VEX Deform
- #
- deformationwrangle/snippet
- Pass Through
- pos = pos;
- xform = xform;
- deformationwrangle/snippet
- Twist
- // Hit the Plug button to generate the UI
- // and change axis.
- vector axis = chv('axis');
- vector center = chv('origin');
- float rate = chf('rotations_per_distance');
- // Find where we are from the center along axis.
- axis = normalize(axis);
- float dist = dot(pos - center, axis);
- float amt = $PI * 2 * rate * dist;
- matrix3 rot = 1;
- rotate(rot, amt, axis);
- pos -= center;
- pos *= rot;
- pos += center;
- #
- # Volume Wrangle
- #
- volumewrangle/snippet
- Create Points where Positive
- // You may want to turn on Bind Each to Density to
- // apply to all volumes.
- if (@density > 0)
- {
- addpoint(geoself(), @P);
- }
- #
- # Popsteer POPs
- #
- popsteeralign/localforceexpression
- Randomize Force Scale per Particle
- forcescale = rand(@ptnum);
- popsteeralign/localforceexpression
- Randomize Fov per Particle
- usefov = 1;
- fov = rand(@ptnum)*120;
- popsteercohesion/localforceexpression
- Randomize Force Scale per Particle
- forcescale = rand(@ptnum)*10;
- popsteercohesion/localforceexpression
- Randomize Fov per Particle
- usefov = 1;
- fov = rand(@ptnum)*120;
- popsteerobstacle/localexpression
- Randomize Search Distance per Particle
- frontsearchdistance = rand(@ptnum)*10;
- sidesearchdistance = rand(@ptnum)*5;
- popsteerobstacle/localexpression
- Scale Avoidance Force by Pscale
- avoidanceforcescale = 10*1/@pscale;
- breakingforcescale = 10*1/@pscale;
- popsteerpath/localforceexpression
- Randomize Path Variance and Force per Particle
- forcescale = rand(@ptnum)*10;
- pathvariance = rand(@ptnum)*5;
- popsteerseek/localgoalexpression
- Randomize Goal Position per Particle
- // Random goal position in (-10,10) range
- goal.x = (2*rand(@ptnum)-0.5)*10;
- goal.z = (2*rand(@ptnum)+123)-0.5)*10;
- popsteerseek/localforceexpression
- Randomize Force Scale per Particle
- forcescale = rand(@ptnum)*10;
- popsteerseparate/localforceexpression
- Randomize Force Scale per Particle
- forcescale = rand(@ptnum)*10;
- popsteerseparate/localforceexpression
- Randomize Fov per Particle
- usefov = 1;
- fov = rand(@ptnum)*180;
- popsteerseparate/localforceexpression
- Randomize Fov per Particle
- usefov = 1;
- fov = rand(@ptnum)*180;
- popsteerwander/localforceexpression
- Randomize Force XZ direction per Particle
- force.x = (2*rand(@ptnum)-0.5)*10;
- force.z = (2*rand(@ptnum)+123)-0.5)*10;
- sprite/localexpression
- Pass Through
- // 0: Uses offset/size
- // 1: Uses textureindex/row/col
- cropmode = cropmode;
- textureoffset = textureoffset;
- texturesize = texturesize;
- textureindex = textureindex;
- texturerow = texturerow;
- texturecol = texturecol;
- spriterot = spriterot;
- spritescale = spritescale;
- #
- # Group Expression
- #
- groupexpression/snippet
- Within radius 1 sphere of origin
- length(@P) < 1.0
- groupexpression/snippet
- X coordinate less than 0
- @P.x < 0
- groupexpression/snippet
- 30% chance
- rand(@elemnum) < 0.3
- #
- # Attribute Expression
- #
- attribexpression/snippet
- Pass Through
- self
- attribexpression/snippet
- Constant Value
- value
- attribexpression/snippet
- Multiply by Constant Value
- self * value
- attribexpression/snippet
- Add Constant Value
- self + value
- attribexpression/snippet
- Random
- rand(@elemnum)
- attribexpression/snippet
- Random Scale of Value
- value * float(rand(@elemnum))
- attribexpression/snippet
- Random Offset of Value
- value + rand(@elemnum)
- attribexpression/snippet
- Second Input's Position
- @opinput1_P
- attribexpression/snippet
- Flatten Vector
- set(self.x, 0, self.z)
- attribexpression/snippet
- Uniform Parameter on Polyline
- vertexprimindex(0, @vtxnum) / (primvertexcount(0, @primnum) - 1.0)
- attribexpression/snippet
- Subtract Center of First Input
- self - getbbox_center(0)
- attribexpression/snippet
- Spherify P
- lerp(self,(normalize(self - getbbox_center(0)) * ch("radius")) + getbbox_center(0),ch("Amt"))
- attribexpression/snippet
- Spherify N
- @P - getbbox_center(0)
- attribexpression/snippet
- Morph to 2nd Input
- lerp(self, point(1,"P",@ptnum),ch("Amt"))
- # VEX Channel
- #
- channelwrangle/snippet
- Lookat
- matrix m1 = lookat(0, @t-chv("lookatvec"), chv("upvec") );
- // Rotate the lookat to point to a different axis.
- int mode = chi("rorder");
- if( mode>=0 && mode<=6 )
- m1 = maketransform( /*trs_order=*/0, /*rot_order=*/mode, /*t=*/0, /*r=*/chv("angle"), /*s=*/1 ) * m1;
- @r = cracktransform(0,0,1,0,m1); // Overwrite only the rotation
- channelwrangle/snippet
- Identity
- @t = 0;
- @r = 0;
- @s = 1;
- channelwrangle/snippet
- Distance
- chopTRS c0 = c->fetchInput(0);
- chopTRS c1 = c->fetchInput(1);
- // Compute the vector betweem first and second input.
- // and scale it with a radius parm
- vector dt = normalize(c1.t - c0.t)* chf('radius');
- @t = c0.t + dt; // Translation from first input + radius vector
- @r = c1.r; // Rotation from second input
- @s = c0.s; // Scale from first input
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