A collection of useful snippets for Houdini.
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createAGrouppointsInAGroupToTestAPointGroupMembershipToTestAPrimitiveGroupMembershipToTestAVertexGroupMembershipPointsInGroupCounterPrimitivesInGroupCounterVerticesInGroupCounterPointsListInGroupPrimitivesListInGroupVerticesListInGroupPointGroupsListPrimitiveGroupsListVertexGroupsListEdgeGroupsListGroupExpand
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Mask creation from metaball.
// Mask from metaball [Point Wrangle]
f@mask = clamp(metaweight(@OpInput2,@P),0,1);
@Cd = f@mask;Example
Remapping random from 0:1 to -1:1.
// Remaping random from 0:1 to -1:1 [Point Wrangle]
float random = rand(@ptnum)*2-1;Sets normals in direction from center of circle (start of coordinate system (0,0,0)).
// Sets normals in direction from center of circle [Point Wrangle]
vector k = set(0,0,0);
v@N = normalize(k+@P);Example
Sets a geometry to always appear without lighting in scene.
// Set true (1) for ON and false (0) for OFF. Need Detail in Run Over [Attribute Wrangle]
@gl_lit = 1;Example
Showing a geometry as wireframes.
// Set true (1) for ON and false (0) for OFF. Need Detail in Run Over [Attribute Wrangle]
@gl_wireframe = 1;Example
Uniformly expanding group by a specified distance.
// Need a group filter ('group1') [Point Wrangle]
int pc = pcopen(0, 'P', @P, ch('radius'), chi('maxpts'));
while (pciterate(pc) > 0)
{
int currentpt;
pcimport(pc, 'point.number', currentpt);
setpointgroup(0, 'group1', currentpt, 1);
}Example
Create a group.
// Creation of group called 'mask' (@group_ is a virtual attribute)
i@group_mask = 1;// Creation of group 'mygroup' for each point [Point Wrangle]
setpointgroup(0, "mygroup", @ptnum, 1);// Creation of group 'mygroup' for each primitive [Primitive Wrangle]
setprimgroup(0, "mygroup", @primnum, 1);// Creation of group 'mygroup' for each vertex [Vertex Wrangle]
setvertexgroup(0, "mygroup", @primnum, 1);// Creation of group 'mygroup' for each edge between
// @primnum and @primnum+1 [Attribute Wrangle with Edges Group Type]
setedgegroup(0, "mygroup", @primnum, @primnum+1, 1);Example
Shows how many elements in a group.
// Points in a group ('mygroup') counter [Point Wrangle]
i@count = npointsgroup(0, 'mygroup');Shows how many elements in a group.
// Points in a group ('mygroup') counter [Point Wrangle]
i@count = nprimitivesgroup(0, 'mygroup');Shows how many elements in a group.
// Points in a group ('mygroup') counter [Point Wrangle]
i@count = nverticesgroup(0, 'mygroup');Returns a string array of existing point groups.
// Array of existing point groups
s[]@list = detailintrinsic(0, 'pointgroups');Returns a string array of existing primitive groups.
// Array of existing primitive groups
s[]@list = detailintrinsic(0, 'primitivegroups');Returns a string array of existing vertex groups.
// Array of existing vertex groups
s[]@list = detailintrinsic(0, 'vertexgroups');Returns a string array of existing edge groups.
// Array of existing edge groups
s[]@list = detailintrinsic(0, 'edgegroups');Creation of list of points numbers in a group.
// List of points in a group [Point Wrangle]
i[]@list = expandpointgroup(0, 'mygroup');Creation of list of primitives numbers in a group.
// List of primitives in a group [Primitive Wrangle]
i[]@list = expandprimgroup(0, 'mygroup');Creation of list of vertices numbers in a group.
// List of primitives in a group [Vertex Wrangle]
i[]@list = expandvertexgroup(0, 'mygroup');Create an array.
// Local integer array of size 5
int array[] = {0,1,2,3,4};// Global string array of size 2
s[]@array = {'example_0.rat', 'example_1.rat'};// Local string array of size 2
string array[] = {'example_0.rat', 'example_1.rat'};Generate an array.
// Procedurally generated array of size 10
i[]@myarray;
for(int i=0; i<10; i++){
append(@myarray, i);
}
// Output: [ 0,1,2,3,4,5,6,7,8,9 ]// Procedurally generated vector array of size '@numpt'
v[]@myarray;
for(int i=0; i<@numpt; i++){
vector item = point(0, 'P', i);
insert(@myarray, 0, item);
}
// Output: [ (4.24242, 0.0, 5.0), (3.53535, 0.0, 5.0), etc. ]Iterating over array elements (every second).
// Need listing input primitive numbers on detail
int importarray[] = detail(0, 'prims');
foreach(int i; importarray){
if(i%2 == 0){
setprimattrib(0, 'Cd', i, {0,1,0.2});
}
}Example
Visualize of n-gons on geometry.
// Visualize of n-gons on geometry [Primitive Wrangle]
if (primvertexcount(0, @primnum) < 4){
@Cd = set(0, 1, 0.2);
}Example
Creation of helix from curve.
// Creation of helix from curve [Point Wrangle]
float freq, amp;
vector pos = @P;
freq = chf("freq");
amp = chf("amp");
pos.x += sin(pos.y * freq) * amp;
pos.z += cos(pos.y * freq) * amp;
@P = pos;Example
Sorting circle points.
//Sorting points in a circle (z and y axis) [Point Wrangle]
vector center = getbbox_center(0);
@P -= center;
@grad = atan2(@P.z,@P.y);
@P += center;
// After that needing sort by attribute 'grad'Example
Replacing primitives with points and adding points at each of their centers.
// Points in center [Primitive Wrangle]
addpoint(0,@P);
removeprim(0,@primnum,0);Example
Assigning a point to a group. If points’ position on X axis is more than 0, assign the point to the “mygroup”.
// Points in a group [Point Wrangle]
if(@P.x>0) @group_mygroup = 1;Example
Returns a boolean value whether a point is a member of specified group.
// Points in a group [Point Wrangle]
i@ismember = inpointgroup(0, "group1", @ptnum);Example
Returns a boolean value whether a primitive is a member of specified group.
// Primitive in a group [Primitive Wrangle]
i@ismember = inprimgroup(0, "group1", @primnum);Example
Returns a boolean value whether a vertex is a member of specified group.
// Vertex in a group [Vertex Wrangle]
i@ismember = invertexgroup(0, "group1", @vtxnum);Example
Cut geometry from selected camera with the ability to crop.
// Camera Frustrum [Point Wrangle]
vector pos = toNDC("/obj/cam1", @P);
if (pos.x < 0+ch('overLeft')) removepoint(0, @ptnum);
if (pos.x > 1-ch('overRight')) removepoint(0, @ptnum);
if (pos.y < 0+ch('overDown')) removepoint(0, @ptnum);
if (pos.y > 1-ch('overUp')) removepoint(0, @ptnum);Example
Preserves the silhouette of the geometry in the selected camera, regardless of its distance.
// Silhouette Retain [Point Wrangle]
vector pos = toNDC("/obj/cam1", @P);
pos.z += ch("offset");
@P = fromNDC("/obj/cam1", pos);Example
