Problem summary When the 'rate channel' option within the ParticleEmitter node is set to 'alpha' (to isolate a particle emission area), if the source is a projected image using a Project3D node, the results will not take into consideration the alpha of the projected image and will be generated on the geometry incorrectly.
Customer reported version nuke.11.2v2
Customer reported platform centos7
Steps to reproduce
Open the attached script and enable/disable the Project3D node, while looking through the Scene node.
or
1) Open a new NukeX session
2) Create a Colorwheel node
3) Create a Project3D node downstream from the ColorWheel node, selecting 'project on' value to front
4) Create a Camera node (for the projection) and set the 'Z translate' value to 3, connecting the cam input to the Project3D node.
5) Create a Sphere node, connecting the img source to the Project3D node
6) Create a ParticleEmitter node, connecting the 'emit' input to the Sphere node
7) Within the ParticleEmitter node: a) Set the 'emit rate' value to 1000 b) Turn on the 'rate channel' checkbox and set the value to rgba.alpha c) Set the 'velocity' value to 0.00005
8) Create a Scene node, connecting one input to the Sphere and the other to the ParticleEmitter (for 3D comparison)
9) View the results of the Scene node Result: Projection is mapping to the incorrect part of the Sphere
10) Disable the Project3D node Result: When the projection is not applied the alpha is applied to the Sphere when the particles are cached.
Expected behaviour The particles should be being created only in the alpha specified area projected by the camera.
Actual behaviour The particles are being created based upon the alpha of the image source, not what is being passed through the Project3D node
Workaround Using a UVProject node can help resolve the issue, although the results will need to be refined on a per use basis.
Reproduced by support This bug has been reproduced in: Nuke 11.3v4 - Windows 7 - MacOS 10.14.5 - CentOS 7 Nuke 11.3v1 - Windows 7 Nuke 11.2v1 - Windows 7 Nuke 11.1v1 - Windows 7 Nuke 11.0v1 - Windows 7 Nuke 10.5v1 - Windows 7 Nuke 10.0v1 - Windows 7 Nuke 9.0v1 - Windows 7 Nuke 8.0v1 - Windows 7 - MacOS 10.14.5 - CentOS 7
Earliest version tested Nuke 8.0v1 - This issue appears to be in all versions of the product
