The Viewer API's Camera Gate Layer (which provides the camera gate visible in the Hydra Viewer) applies camera scale incorrectly for perspective cameras. This is clearly evident when a perspective camera is uniformly scaled, an operation that should never affect the screen space position of any point in world space, which currently does scale the camera gate by the x and y scale of the camera transform. The underlying cause of this bug is the ignoring of z scale.
Steps to reproduce:
Open the attached reproduction project ('CameraScale.katana'), or create a project with the following two nodes connected in order:
A CameraCreate with non-unit uniform scale (equal x, y and z, e.g. all 1.5).
A Transform3D node to move the camera off the grid (x-z) plane and tilt it towards the grid such that the grid is visible for perspective and orthographic cameras (e.g. translate.y=1, rotate.x=-30).
Open both a Hydra Viewer tab and an OSG Viewer tab and in both, look through the scene camera. Both Viewers display the correct camera field of view (extended in the long axis, where appropriate), but the camera gate (screen window) displayed in the Hydra Viewer is incorrectly scaled up by the camera's scaling factor (e.g. 1.5).
Workaround:
Avoid scaling cameras
Tested versions/platforms:
3.0v1 - Affected
4.0v5 - Affected
Versions prior to 3.0v1 had different behaviour for displaying scaling in the Hydra Viewer, but did not exhibit this specific bug.