Experimental: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

Parameters - Common Page

Operator Inputs

• Input 0: -

Info CHOP Channels

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

Common POP Info Channels

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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