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Maniphest T62621

object scale changes tangent node output in Eevee
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Description

System Information
Operating system: Linux-4.13.10-041310-generic-x86_64-with-debian-stretch-sid 64 Bits
Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.67

Blender Version
Broken: version: 2.80 (sub 48), branch: blender2.7, commit date: 2019-03-14 22:54, hash: rB35b78d9807c4
Worked: rBbf9904ec8018

Short description of error
Depending on the object scale, the tangent node will output different vectors in Eevee. In Cycles scale has no effect on it.
In rBbf9904ec8018, this was not an issue either.

Exact steps for others to reproduce the error

  • open attached blend
  • scale one of the planes down and notice how the color changes (slightly)
  • apply the scale and it matches the other, unscaled plane's color again
  • optionally pipe in the transform node to check on different colors
  • also compare in cycles and in rBbf9904ec8018, to find no such change in output/color
  • see https://www.youtube.com/watch?v=_qlhz7R02rQ for a video demo

object_scale_changes_tangent_node_output_in_eevee.blend103 KBDownload

Revisions and Commits

rB Blender
rBcc1b193ddf38 Revert "Fix T62621 object scale changes tangent node output in Eevee"
rB27109fd209ca Eevee: Normalize Tangents after transform to world space
rB86646dab7c45 Fix T62621 object scale changes tangent node output in Eevee

Related Objects

Event Timeline

MACHIN3 (MACHIN3) created this task.Mar 15 2019, 7:27 PM
MACHIN3 (MACHIN3) added a comment.Mar 15 2019, 7:50 PM

I suspect rB7fb7d20c19e2 is causing this.

Brecht Van Lommel (brecht) assigned this task to Clément Foucault (fclem).EditedMar 15 2019, 8:01 PM
Brecht Van Lommel (brecht) added subscribers: Clément Foucault (fclem), Brecht Van Lommel (brecht).

@Clément Foucault (fclem), for the mikktspace tangent that Blender (and other apps) use, the tangents are intended to be interpolated without normalization.
https://archive.blender.org/wiki/index.php/Dev:Shading/Tangent_Space_Normal_Maps/#Pixel_Shader_Transformation

Brecht Van Lommel (brecht) lowered the priority of this task from 90 to 50.Mar 15 2019, 8:01 PM
Clément Foucault (fclem) added a comment.Mar 15 2019, 10:24 PM

@Brecht Van Lommel (brecht) while I'm all in fixing the normalize issue, this report is completely unrelated. The NormalMatrix is not normalize and thus does not produce normalized vector after the rotation. I'm fixing both issue...

Clément Foucault (fclem) changed the task status from Unknown Status to Resolved by committing rB86646dab7c45: Fix T62621 object scale changes tangent node output in Eevee.Mar 15 2019, 10:33 PM
Clément Foucault (fclem) added a commit: rB86646dab7c45: Fix T62621 object scale changes tangent node output in Eevee.
Clément Foucault (fclem) added a commit: rBcc1b193ddf38: Revert "Fix T62621 object scale changes tangent node output in Eevee".Mar 22 2019, 12:13 AM
Clément Foucault (fclem) added a commit: rB27109fd209ca: Eevee: Normalize Tangents after transform to world space.