Topology POP

Summary

The Topology POP gives finer control on how to combine existing points and topology (vertices and primitives), as well as their memory allocation.

Any unsigned int attribute from the input POP or another POP, interpreted as a list of point indices, can be used to describe the topology of the POP, alongside a manual description of the number of primitives (Topology Info), either using the parameters when the number of primitives of each type are known on the CPU, or using values coming from attributes, when the number of primitives of each type are only known on the GPU. This allows to combine multiple buffers created with GLSL and GLSL Advanced POP to describe geometry for example.

Alternatively the Topology and Topology info can be provided from another POP. Primitives and Vertices attributes can also be merged in from other POPs.

Last but not least, for POPs whose numbers of points and primitives are known on the GPU, the maximum numbers can be updated here, if the user knows them to be smaller, to reduce the memory allocation of downstream POPs. Alternatively if the exact counts are known they can also be entered manually and the POP updated to know that its point count info and topology info are now known on the CPU, without incurring the cost and stall of a download. (Refer to Learning about POPs, Information known on CPU/GPU)

topologyPOP_Class

Parameters - Points Page

Max Points maxpointsmode - ⊞ - Specifies how to set the maximum number of points.

• Max Points maxpointsmode -

• Max Points maxpoints - Sets the max number of points. If the POP point count info is on the CPU, that's the actual number of points.

Point Count Info pointcountinfo - ⊞ - Input point count source.

• From Input input -

• From Max Points Parameter fromparams -

• From Attribute fromattrs -

Point Count POP pointcountpop - POP that holds the point counts.

Point Count Attribute pointcountclass - ⊞ - Attribute class of the attribute that holds the point count.

• Point Count Attribute pointcountclass -

• Point Count Attribute pointcountattr - Attribute that holds the point count.

Parameters - Topology Page

Render render - Enables rendering in the viewer. Disable when output data is in an intermediate or non-renderable state

Primitive Source Mode primsourcemode - ⊞ - Whether the input POP is the primitive source or a different POP is used as the primitive source. Other parameters refer to the primitive source.

• Input input -

• Specify POP specpop -

Primitive Mode primmode - ⊞ - Whether the primitive source input is used for the topology and topology info, or an attribute is used to specify the topology (the point indices), and the topology info is specified manually.

• Source Topology and Topology Info topo -

• Source Attribute and Manual Topology Info attr -

Primitives POP primspop - Specifies the POP to use for the primitive source.

Point Index Attrib Class pointindexattrclass - ⊞ - Attribute class of the attribute that holds the point index values.

• Point Index Attrib Class pointindexattrclass -

• Point Index Attrib Name pointindexattrname - Attribute that holds the Point Index values.

Vertex Attribute Mode vertattrmode - ⊞ - Specifies whether the vertex attributes come from the vertex source (input or separate POP) or from a separate POP

• None none -

• Primitive Source primsource -

• Specify POP specpop -

Vertex Attribute POP vertattrpop - The POP from which the vertex attributes come from.

Vertex Attribute Class vertattrclass - ⊞ - The attribute class from the vertex attributes when they come from the specified POP.

• Point point -

• Vertex vertex -

• Primitive primitive -

Prim Attribute Mode primattrmode - ⊞ - Specifies whether the primitive attributes come from the primitive source (input or separate POP) or from a separate POP.

• None none -

• Primitive Source primsource -

• Specify POP specpop -

Prim Attribute POP primattrpop - The POP from which the primitive attributes come from.

Prim Attribute Class primattrclass - ⊞ - The attribute class from the primitive attributes when they come from the specified POP.

• Point point -

• Vertex vertex -

• Primitive primitive -

Topology topology - ⊞ - Determines the topology mode.

• Source Topology Reference ref -

• Source Topology Copy copy -

Max Triangles maxtrianglesmode - ⊞ - Specifies how to set the maximum number of triangle primitives.

• Max Triangles maxtrianglesmode -

• Max Triangles maxtriangles - Sets the max number of triangle primitives. If the POP topology info is on the CPU, that's the actual number of triangle primitives.

Max Quads maxquadsmode - ⊞ - Specifies how to set the maximum number of quad primitives.

• Max Quads maxquadsmode -

• Max Quads maxquads - Sets the max number of quad primitives. If the POP topology info is on the CPU, that's the actual number of quad primitives.

Max Line Strips maxlinestripsmode - ⊞ - Specifies how to set the maximum number of line strip primitives.

• Max Line Strips maxlinestripsmode -

• Max Line Strips maxlinestrips - Sets the max number of line strip primitives. If the POP topology info is on the CPU, that's the actual number of line strip primitives.

Max Line Strip Verts maxlsvertsmode - ⊞ - Specifies how to set the maximum number of vertices per line strip.

• Max Line Strip Verts maxlsvertsmode -

• Max Line Strip Verts maxlsverts - Sets the max number of line strip vertices. If the POP topology is on the CPU, that's the actual number of line strip vertices.

Max Lines maxlinesmode - ⊞ - Specifies how to set the maximum number of line primitives.

• Max Lines maxlinesmode -

• Max Lines maxlines - Sets the max number of line primitives. If the POP topology info is on the CPU, that's the actual number of line primitives.

Max Point Prims maxpointprimsmode - ⊞ - Specifies how to set the maximum number of point primitives.

• Max Point Prims maxpointprimsmode -

• Max Point Prims maxpointprims - Sets the max number of point primitives. If the POP topology info is on the CPU, that's the actual number of point primitives.

Line Strip Info from Prim Source lsinfofromprimsource - When set, uses the primitive source (Input or Specified POP) for the Line Strip Info buffer.

Line Strip Info Update lsinfoupdate - ⊞ - Allows you to choose how the Line Strip Info buffers get updated.

• Auto auto -

• Manual manual -

Line Strip Info POP lsinfopop - POP with the attribute to use for the Line Strip Info buffer.

Line Strip Info Attribute lsinfoclass - ⊞ - Attribute class of the attribute to use foor the Line Strip Info buffer.

• Line Strip Info Attribute lsinfoclass -

• Line Strip Info Attribute lsinfoattr - Attribute to use for the Line Strip Info buffer.

Line Strip Index per Vert POP lsindexpop - POP with the attribute to use for the Line Strip Index per Vert buffer.

Line Strip Index per Vert Attribute lsindexclass - ⊞ - Attribute class of the attribute to use for the Line Strip Index per Vert buffer.

• Line Strip Index per Vert Attribute lsindexclass -

• Line Strip Index per Vert Attribute lsindexattr - Attribute to use for the Line Strip Index per Vert buffer.

Max Verts per Line Strip lsmaxvertsoverride - ⊞ - Specifies you wan to set the max number of verts per line strip.

• Max Verts per Line Strip lsmaxvertsoverride -

• Max Verts per Line Strip lsmaxverts - Sets the max number of verts per line strip. Used by some downstream POPs for GPU memory allocation.

Topology Info topoinfo - ⊞ - Sets the topology information source.

• From Primitive Source primsource -

• From Max Prims Parameter fromparams -

• From Attributes fromattrs -

Topology Info POP topoinfopop - Sets reference to a POP where the info attribute can be found.

Topology Info Attributes Class topoinfoclass - ⊞ - Sets the attribute class where the info attribute can be found.

• Point point -

• Vertex vertex -

• Primitive primitive -

Triangle Count trianglecountmode - ⊞ - Whether to get the count of triangle primitives from the source, set it to 0, or set its value manually.

• Triangle Count trianglecountmode -

• Triangle Count Attribute trianglecountattr - Specifies the attribute to use to set the triangles count.

Quad Count quadcountmode - ⊞ - Whether to get the count of quad primitives from the source, set it to 0, or set its value manually.

• Quad Count quadcountmode -

• Quad Count Attribute quadcountattr - Specifies the attribute to use to set the quadrilaterals count.

Line Strip Count linestripcountmode - ⊞ - Whether to get the count of line strip primitives from the source, set it to 0, or set its value manually.

• Line Strip Count linestripcountmode -

• Line Strip Count Attribute linestripcountattr - Specifies the attribute to use to set the line count.

Line Strip Vert Count lsvertcountmode - ⊞ - Specifies how to set the line strip vertex count.

• Line Strip Vert Count lsvertcountmode -

• Line Strip Vert Count Attribute lsvertcountattr - Specifies how to set the line strip vertex count.

Line Count linecountmode - ⊞ - Whether to get the count of line primitives from the source, set it to 0, or set its value manually.

• Line Count linecountmode -

• Line Count Attribute linecountattr - Specifies the attribute to use to set the line count.

Point Prim Count pointprimcountmode - ⊞ - Whether to get the count of point primitives from the source, set it to 0, or set its value manually.

• Point Prim Count pointprimcountmode -

• Point Prim Count Attrib pointprimcountattr - Specifies the attribute to use for the point primitive count.

Parameters - Common Page

Bypass bypass - Pass through the first input to the output unchanged.

Free Extra GPU Memory freeextragpumem - Free memory that has accumulated when output memory has grown and shrunk.

Delete Input Attributes delinputattrs - Only output which attributes you specify in this POP - helps isolate attributes into a separate branch.

Operator Inputs

• Input 0: -

Info CHOP Channels

Extra Information for the Topology POP can be accessed via an Info CHOP.

Common Operator Info Channels

• total_cooks - Number of times the operator has cooked since the process started.

• cook_time - Duration of the last cook in milliseconds.

• cook_frame - Frame number when this operator was last cooked relative to the component timeline.

• cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.

• cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.

• cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.

• cooked_this_frame - 1 if operator was cooked this frame.

• warnings - Number of warnings in this operator if any.

• errors - Number of errors in this operator if any.

TouchDesigner Build: Latest\nwikieditor2025.30000

POPs (Point Operators) is a new Operator Family of TouchDesigner that runs on the GPU accelerated graphics card or chips, and creates/modifies 3D data which is rendered by the Render TOP or passed to devices like DMX lighting, LED arrays, lasers or other external systems.

The Graphics Processing Unit. This is the high-speed, many-core processor of the graphics card/chip that takes geometry, images and data from the CPU and creates images and processed data.

A sequence of vertices form a Polygon in a SOP. Each vertex is an integer index into the Point List, and each Point holds an XYZ position and attributes like Normals and Texture Coordinates.

Every operator in TouchDesigner has a set of control Parameters that can be integer or floating point numbers, menus, binary toggles, text strings or operator paths, which determine the output of the operator.

A surface type in SOPs that includes polygon, curve (NURBS and Bezier), patch (NURBS and Bezier) and other basic shapes like sphere, tube and metaball. Points and Primitives are part of the Geometry Detail, which is a part of a SOP.

A sequence of vertices form a Polygon in a SOP. Each vertex is an integer index into the Point List, and each Point holds an XYZ position and attributes like Normals and Texture Coordinates.

Each SOP has a list of Points. Each point has an XYZ 3D position value plus other optional attributes. Each polygon Primitive is defined by a vertex list, which is list of point numbers.

A Link. The grey dashed lines between nodes is a Reference or Link that indicates one operator is getting data from another operator from any Operator Family.

The grey dashed lines between nodes is a Reference (or Link). A Reference is (1) a Parameter Reference, a parameter in an OP that is a name or path to another operator, (2) a Node Reference, an expression in a parameter or DAT script that contains the name or path of another operator, (3) a DAT Cell Reference or (4) a CHOP Channel Reference.

A Link or Reference is a dashed line between nodes that represent other data flowing between nodes. Examples are CHOP Exports, node Paths in parameters, and expressions in parameters referencing CHOP channels, DAT tables and other nodes. In contrast is a Wire that connects nodes in the same Operator Family.

Attributes are data associated with POP geometry. Points, Vertex (Vertices) and Primitives (polygons, lines, etc) can have any number of attributes.

An operator whose Bypass flag is set does nothing: All data going into its first input appears at its output unaffected.

An Operator Family which operate on Channels (a sequence of numbers (Samples)) which are used for animation, audio, mathematics, simulation, logic, UI construction, and data streamed from/to devices and protocols.