ID 430284 - The alpha can become inverted when splines cross over one another in a Roto/Paint node.

Problem summary

The alpha can become inverted when splines cross over one another in a Roto/Paint node.

Customer reported version
nuke.n/a

Customer reported platform

Steps to reproduce

1) In Nuke, create a Roto node.

2) Make a spline cross over itself.

3) View the Alpha by pressing A in the Viewer.

4) Select a point and add a keyframe to transform the Roto spline.

5) Observe the alpha.

Example Roto:

set cut_paste_input [stack 0]

version 9.0 v1

push $cut_paste_input

Roto {

 output alpha

 curves {{{v x3f99999a}

  {f 0}

  {n

  {layer Root

    {f 0}

    {t x44f00000 x44870000}

    {a pt1x 0 pt1y 0 pt2x 0 pt2y 0 pt3x 0 pt3y 0 pt4x 0 pt4y 0 ptex00 0 ptex01 0 ptex02 0 ptex03 0 ptex10 0 ptex11 0 ptex12 0 ptex13 0 ptex20 0 ptex21 0 ptex22 0 ptex23 0 ptex30 0 ptex31 0 ptex32 0 ptex33 0 ptof1x 0 ptof1y 0 ptof2x 0 ptof2y 0 ptof3x 0 ptof3y 0 ptof4x 0 ptof4y 0 pterr 0 ptrefset 0 ptmot x40800000 ptref 0}

    {curvegroup Bezier1 512 bezier

    {{cc

      {f 8192}

      {px

        {x40800000 x41200000}

        {{0}

  {0}}

        {{x44bc5ffd}

  {x448de000}}

        {{0}

  {0}}

        {{xc356a3e8 xc35cb148}

      {x42902938 x424a6b80}}

        {{{x44ae2003 0 1 x40d55555 1}

      {x44bc2005 x40d55555 1 0 1}}

      {{x4468c002 0 1 xc0800015 1}

      {x4462c001 xc0800015 1 0 1}}}

        {{x43060000 x431cffe8}

      {xc233fff0 xc2100020}}

        {{xc3520000}

  {xc37f0000}}

        {{x44e06000}

  {x44988000}}

        {{x43520000}

  {x437f0000}}

        {{x43390000}

  {x42f00000}}

        {{x44e78000}

  {x44bc0000}}

        {{xc3390000}

  {xc2f00000}}

        {{x41f00000}

  {0}}

        {{x4517bffe}

  {x443a8002}}

        {{xc1f00000}

  {0}}}}    idem}

    {tx x43868000 x44c9e000 x44a60000}

    {a osw x41200000 osf 0 str 1 spx x44f00000 spy x44870000 sb 1 ltn x43868000 ltm x43868000 tt x40800000}}}}}}

 toolbox {selectAll {

  { selectAll str 1 ssx 1 ssy 1 sf 1 }

  { createBezier str 1 ssx 1 ssy 1 sf 1 sb 1 tt 4 }

  { createBezierCusped str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { createBSpline str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { createEllipse str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { createRectangle str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { createRectangleCusped str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { brush str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { eraser src 2 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { clone src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { reveal src 3 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { dodge src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { burn src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { blur src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { sharpen src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

  { smear src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }

} }

 toolbar_brush_hardness 0.200000003

 toolbar_source_transform_scale {1 1}

 toolbar_source_transform_center {1920 1080}

 colorOverlay {0 0 0 0}

 lifetime_type "all frames"

 lifetime_start 269

 lifetime_end 269

 motionblur_shutter_offset_type centred

 source_black_outside true

 name Roto1

 selected true

 xpos 18

 ypos -78

}

Expected behavior
The alpha should remain the same throughout the Roto.

Actual behavior
The alpha becomes inverted on the Roto spline.

Workaround
There is no available workaround at this time.

Reproduced by Support in
Nuke 12.1v1 - Windows 10

Nuke 12.0v1 - Windows 10

Nuke 11.0v1 - Windows 10

Nuke 10.0v1 - Windows 10

Nuke 9.0v1 - Windows 10

Earliest version tested
Nuke 9.0v1 - This issue appears to be in all versions of the product