[Bf-cycles] Strange behaviour with pictures

[Thomas Dinges]

Hi,
Image Loading in Cycles goes via the OpenImageIO library, Image Loading 
in Blender goes via our own Blender code.
It looks like Blender caches the image somehow, so Material & Texture 
view still work.

OpenImageIO on the other hand reloads the image every time. There are 
some ToDos for Image loading via OpenImageIO, but this is not considered 
a bug atm.

Regards,
Thomas

Am 14.08.2012 16:36, schrieb Christian Monfort:
> Hi,
>
> I've discovered something using Cycles that I'll consider a bug unless
> someone here tells me it's not (in which case I'll find it a bit
> annoying):
> it seems that Cycles needs to have access all the time to pictures
> used in materials
> if not - because the file has been removed/rename, or is not accesible
> - the material is rendered all black:
>
> How to reproduce:
>
> 0) Start from default scene
> 1) Switch to Cycles Render
> 2) Open image in UV/Image Editor (let's say /tmp/pic1.png)
> 3) Quick UV/Unwrap the cube
> 4) In node editor, add a new material to cube (you should have
> "Diffuse BSDF" & "Material Output" default nodes)
> 5) Add an "Image texture" node, selected previously loaded image, and
> connect Color pins from "Image texture" && "Diffuse BSDF" nodes:
>     [ Image.Texture/Color ] <--> [ Color/Diffuse.BSDF/BSDF ] <--> [
> Surface/Material.Ouput ]
> 5) Set Viewport shading to "Rendered" in 3D view = > All is ok,
> picture on all cube faces
>
> 6) Rename picture file on disk (/tmp/pic1.png => /tmp/pic2.png)
> 7) All is still ok in 3D view,
> 8) Set view port shading to something else than "Rendered" ("Solid"
> for example),
> 9) then back to "Rendered" => cube is all black... (But "Material" and
> "Texture" shading modes are OK)
>
> Ok, maybe that's normal as we removed the picture file...
> (but isn't the picture loaded in Blender somewhere? why Material &
> Texture mode ok then?)
>
> 10) Rename back picture file to /tmp/pic1.png" and repeat 8) 9)
> 11) => Picture on all cube faces
>
> Let's try something else...
>
> 12) In UV/Image editor Select "Pack Image" from "Image" menu, so that
> all image data is embeded in .blend
> 13) Check all is ok in "Rendered" mode, then repeat 6) 7) 8) 9)
> 14) => Cube is all black...
>
> I may understand the 1st case (up to point 9) - but here I thought
> that packing image made that Blender needed the original file no
> more... and still Cycles do?
>
> Thanks for your time
> (I don't want to open a bug report until I'm 100% sure this is not a
> correct behaviour...)
>
> Christian.
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> Bf-cycles at blender.org
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-- 
Thomas Dinges
Blender Developer, Artist and Musician

www.dingto.org