Projection POP

Summary

The Projection POP takes a float3 3D spatial attribute, like P, and outputs to a float3 attribute, transforming the attribute between cartesian (orthographic), polar, cylindrical, and perspective coordinate systems. For example, all the the points in cartesian X, Y and Z format can be converted into a polar longitude/latitude/radius format.

The menu From Coordinate System lets you choose how to interpret the 3 numbers of the input attribute:

• Cartesian treats the 3 numbers of the float3 attribute as X, Y and Z in the usual 3D "orthogonal" coordinate space. (In TouchDesigner X is horizontal left-to-right, Y is vertical bottom to top. Z is along line of sight distant to near.)
• Spherical treats the three numbers of the attribute as longitude, latitude and radius, assuming the axis is the vertical Y axis.
• Cylindrical treats the 3 numbers of the attribute as latitude (angle around Y), Y value and a radius.
• Screen Space is a perspective form along the Z axis - you need to specify additional camera/perspective info. 0,0 is the bottom left corner, 1, 1 is top right.
• Normalized Device Coordinates (NDC) - For points within the field of view, the first and second components are between -1 and 1 where 0,0 is at the center. The third component is between 0 and 1 (as re-ranged to the Near and Far distances).

The menu To Coordinate System lets you choose what form you want the 3 numbers of the output attribute to be in.

The angles can be expressed in

• Degrees in the usual graphics standard (360 is a full rotation), or
• Radians (Pi 3.14157 is one full rotation)
• Cycles (value of 1 means one full 360 degrees rotation)
• Normalized - a 0-1 normalized form which, like Spherical longitude is like a wraparound: looking along the -Z axis, the value is 0 at the back, .25 the left, .5 is face-on, .75 at the right, and 1 at the back. For latitude the value goes from 0 at the south pole and 1 at the north pole. This is used for mapping a texture on a sphere sometimes.

See also tbe Sphere POP, Tube POP, Normalize POP and the Texture Map POP.

projectionPOP_Class

Parameters - Projection Page

Attribute Class attrclass - ⊞ - Makes the POP operate on point attributes, vertex attributes or primitive attributes where applicable.

• Point point -

• Vertex vertex -

• Primitive primitive -

Group group - If there are input groups, specifying a group name in this field will cause this POP to act only upon the group specified.

Input Attribute Scope inputattrscope - Input's attributes you want to affect within the chosen attribute class, or attribute components.

From Coordinate System fromcoordsys - ⊞ - The coordinate system to convert from.

• Cartesian cartesian -

• Spherical spherical -

• Cylindrical cylindrical -

• Screen Space screenspace -

• Normalized Device Coordinates ndc -

To Coordinate System tocoordsys - ⊞ - Specifies the target coordinate system for the operation.

• Cartesian cartesian -

• Spherical spherical -

• Cylindrical cylindrical -

• Screen Space screenspace -

• Normalized Device Coordinates ndc -

Angle Units angunit - ⊞ - The unit for the angles, when some of the coordinates are angles in the source or destination coordinate system.

• Degrees deg -

• Radians rad -

• Cycles cycle -

• Normalized norm -

Camera camera - Specify the camera component.

Aspect Correct UVs aspectcorrectuv - Whether respect the aspec ratio for the projection.

Aspect Ratio aspect - ⊞ - The aspect ratio of the camera projection.

• Aspect Ratio aspectx -

• Aspect Ratio aspecty -

Horizontal FOV fov - Horizontal field of view when source or destination coordinate system is screen space or normalized device coordinates.

Near Depth depthnear - Depth of the near clipping plane.

Far Depth depthfar - Depth of the far clipping plane.

Output Attribute Scope outputattrscope - ⊞ - Name of attribute to output (can choose components of attribute), can choose from menu.

• P P -

• N N -

• Color Color -

• Color.rgb Color.rgb -

• Tex Tex -

• PointScale PointScale -

• LineWidth LineWidth -

Override Automatic Attribute overrideautoattr - Whether to override the kind of attribute automatically created based on the POP input and parameters. Allows to specify manually the type and number of components of the new attribute.

Attribute Type attrtype - ⊞ - The output attribute's data type, default float.

• float float -

• double double -

• int int -

• uint uint -

• Color color -

• Color (double) dcolor -

• Direction dir -

• Direction (double) ddir -

Components attrnumcomps - ⊞ - The number of components in the new custom attribute.

• 1 1 -

• 2 2 -

• 3 3 -

• 4 4 -

Default Value attrdefaultval - ⊞ - Default values of the output attribute components if they cannot be computed.

• Default Value attrdefaultval0 - Default value(s) of the attribute.

• Default Value attrdefaultval1 - Default value(s) of the attribute.

• Default Value attrdefaultval2 - Default value(s) of the attribute.

• Default Value attrdefaultval3 - Default value(s) of the attribute.

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 Projection 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.

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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.

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 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.

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 Group in POPs and SOPs is a named subset of points or primitives. It is created with the Group POP or Group SOP. Numerous operations in POPs and SOPs (using a Group parameter) can be restricted to affect the points or primitives in selected groups, and not affect others.

A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator. TOPs have Channel Mask, a similar feature.

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

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.

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

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.