Using Min Max of the Mapping node and texture extrapolation #45557

New Issue

Emmanuel LORANT · 2015-07-25T12:07:20+02:00

Emmanuel LORANT commented

2015-07-25 12:07:20 +02:00

System Information
Operating system and graphics card

Windows 7 Ultimate x64

Blender Version
Broken: 2.75
Worked: (optional)

Short description of error

When using the Min Max of the mapping node, if the texture has not alpha on boundaries, the extrapolation of the color is weird.

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps

There are 2 blend files, one with a texture where the top is alpha but not the bottom : http:*www.pasteall.org/blend/37266 and the 2nd blend has the same texture but with a row of one pixel of alpha at the bottom and then, it works as expected : http:*www.pasteall.org/blend/37267

Just go in Rendered mode to see differences.

**System Information** Operating system and graphics card Windows 7 Ultimate x64 **Blender Version** Broken: 2.75 Worked: (optional) **Short description of error** When using the Min Max of the mapping node, if the texture has not alpha on boundaries, the extrapolation of the color is weird. **Exact steps for others to reproduce the error** Based on a (as simple as possible) attached .blend file with minimum amount of steps There are 2 blend files, one with a texture where the top is alpha but not the bottom : http:*www.pasteall.org/blend/37266 and the 2nd blend has the same texture but with a row of one pixel of alpha at the bottom and then, it works as expected : http:*www.pasteall.org/blend/37267 Just go in Rendered mode to see differences.

Emmanuel LORANT commented

2015-07-25 12:07:20 +02:00

Changed status to: 'Open'

Emmanuel LORANT commented

2015-07-25 12:07:20 +02:00

Added subscriber: @EmmanuelLORANT

Sergey Sharybin commented

2015-07-28 14:52:45 +02:00

Added subscriber: @Sergey

Sergey Sharybin commented

2015-07-28 14:52:45 +02:00

Changed status from 'Open' to: 'Resolved'

Sergey Sharybin closed this issue

2015-07-28 14:52:45 +02:00

Sergey Sharybin self-assigned this 2015-07-28 14:52:45 +02:00

Sergey Sharybin commented

2015-07-28 14:52:45 +02:00

This isn't a bug in the mapping node, it does exactly what you're asking to do -- it clamps coordinates to 0..1 range, making it behave like Extend texture mapping when texture is being extended across it's edge when texture coordinate is outside of 0..1 range. Only issue with that is that due to linear intepolation setting and texture being used as Repeat extension type it blends edge with the warped coordinate.

What you might do instead is to use Clip extension type of the image texture which was just added to Cycles (see f296259) and disable min/max setting in the mapping node.

So thanks for the report, it is now possible to achieve effect you want with the next upcoming nightly build.

This isn't a bug in the mapping node, it does exactly what you're asking to do -- it clamps coordinates to 0..1 range, making it behave like Extend texture mapping when texture is being extended across it's edge when texture coordinate is outside of 0..1 range. Only issue with that is that due to linear intepolation setting and texture being used as Repeat extension type it blends edge with the warped coordinate. What you might do instead is to use Clip extension type of the image texture which was just added to Cycles (see f296259) and disable min/max setting in the mapping node. So thanks for the report, it is now possible to achieve effect you want with the next upcoming nightly build.

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Using Min Max of the Mapping node and texture extrapolation #45557