Blender Discussions

[gelert]

In v2.0.85 of RPR for Blender the RGB Curves Node has no effect on the output.

A secondary bug is also present in the Checker Texture Node where the resulting checkers are a very different size / scale to the Checker Node when used with Cycles or EEVEE. It would be good if RPR for Blender could apply a factor to the checker texture node automatically so that it's output better matched the Blender default.

A simple sample file is attached and screenshots are shown below for each engine.

Result in EEVEE:

Result in Cycles:

Result in RPRv2085:

[arozghon]

looks like Eevee and Cycles use other algorithm for generators uv's calculation and RPR use mesh UVs 

[inputhone]

I had the same issue, also texture coordinate and mapping seem to result in a different mapping when switching between cycles and rpr. this to me also also happened though the object is unwraped and image coordinate is set to UV.

[bsavery]

Are there UV's applied to the object?  If not Cycles does some weird "generated" uv scheme.

[gelert]

Sample file does indeed have UV's applied. Screenshot attached.

I believe Blender 2.80 adds a default UV to all newly created meshes unlike 2.79. It might not be the best UV but at least it avoids the issue where textures don't appear to do anything when you forgot that.

I know internally RPR is using a different scale (percentage?) for it's various textures but when using the host 3D's app nodes the plug-in should attempt to apply a factor so that it better matches the host app's scaling where possible for compatibility. This issue applies to image texture scaling too where RPR's output is very different to EEVEE / Cycles for the exact same node tree and image files.

[bsavery]

So this is interesting. If you add the UV map node and hook up to the checker "vector" input.  Their is the same as ours.

This leads me to the conclusion:

1.  If RPR has nothing hooked up to a texture "vector" input, we use the uv map.  (basically we make a virtual UV lookup node

2. If cycles/eevee does not, then they do... something different.  Needs some investigation into what exactly!

[bsavery]

Also I fixed the RGB curve issue.  Blender was applying the C curve differently than we were.

[gelert · Accepted solution]

I can confirm that in v2.0.94 of RPR for Blender 2.80 that this bug is indeed fixed.

So long as a Texture Coordinate set to UV and a Mapping node set to Vector is used all of the texture Scaling is absolutely 100% the same as Cycles and EEVEE when using RPR. This is fantastic. Thank you.