Eevee mipmaps not respecting border mode #73942

New Issue

Nathan Vasil · 2020-02-17T20:28:40+01:00

Nathan Vasil commented

2020-02-17 20:28:40 +01:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 432.00

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: 77d23b0bd7
Also broken 2.83 alpha hash f6d5a95513

Short description of error
Mipmaps used by Eevee appear to always be generated using tiling border mode, as if texture access mode is just set by modulo coordinates rather than setting the border sampling mode for the hardware.

This is true for both extend and clip modes of texture access.

I can't currently select Cycles rendering engine in 2.82 (presumably a different bug) but the problem doesn't exist in Cycles in 2.83 alpha or in previous versions where I've seen this bug (2.81 and 2.80 if I remember correctly), only in Eevee.

Exact steps for others to reproduce the error

Attached file demonstrates the bug. A plane with a magenta->black gradient texture is set to clip mode. You may need to zoom out to get a visible mipmap demonstrating the problem, as the mipmap chosen should depend on your own personal resolution.

mipclipbug.blend

Change to rendered view. At a suitable zoom, a magenta bar is visible on the rightmost margin of the plane.

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 432.00 **Blender Version** Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: `77d23b0bd7` Also broken 2.83 alpha hash f6d5a9551380 **Short description of error** Mipmaps used by Eevee appear to always be generated using tiling border mode, as if texture access mode is just set by modulo coordinates rather than setting the border sampling mode for the hardware. This is true for both extend and clip modes of texture access. I can't currently select Cycles rendering engine in 2.82 (presumably a different bug) but the problem doesn't exist in Cycles in 2.83 alpha or in previous versions where I've seen this bug (2.81 and 2.80 if I remember correctly), only in Eevee. **Exact steps for others to reproduce the error** Attached file demonstrates the bug. A plane with a magenta->black gradient texture is set to clip mode. You may need to zoom out to get a visible mipmap demonstrating the problem, as the mipmap chosen should depend on your own personal resolution. [mipclipbug.blend](https://archive.blender.org/developer/F8345606/mipclipbug.blend) Change to rendered view. At a suitable zoom, a magenta bar is visible on the rightmost margin of the plane.

Nathan Vasil commented

2020-02-17 20:28:40 +01:00

Added subscriber: @vasiln

Nathan Vasil commented

2020-02-17 20:37:47 +01:00

Since this could potentially be related to specific hardware, here's a screenshot:

Also shows up in renders:

Since this could potentially be related to specific hardware, here's a screenshot: ![image.png](https://archive.blender.org/developer/F8345616/image.png) Also shows up in renders: ![mipbug2.png](https://archive.blender.org/developer/F8345620/mipbug2.png)

Richard Antalik commented

2020-02-18 11:50:17 +01:00

Added subscriber: @iss

Richard Antalik commented

2020-02-18 11:50:17 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Richard Antalik commented

2020-02-18 11:50:17 +01:00

Seems to happen only with linear interpolation in texture node.

Jacques Lucke commented

2020-02-18 11:57:04 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-02-18 11:57:04 +01:00

I'm not sure why it behaves as it does, but it does look wrong. I can also confirm that it works as expected in Cycles.
2020-02-18 11-52-22.mp4

I'm not sure why it behaves as it does, but it does look wrong. I can also confirm that it works as expected in Cycles. [2020-02-18 11-52-22.mp4](https://archive.blender.org/developer/F8347272/2020-02-18_11-52-22.mp4)

Nathan Vasil commented

2020-02-18 21:01:50 +01:00

Extra info: problem exists regardless of linear, cubic, or smart filtering. No problem, of course, with closest (no mip) filtering.

Jacques Lucke commented

2020-05-20 16:47:08 +02:00

Added subscriber: @fclem

Jacques Lucke commented

2020-05-20 16:47:08 +02:00

The issue seems to be that point_texco_clamp assumes lod level 0 when querying the texture size. From what I've read, we can't simply clamp between 0 and 1, because textures are sampled at pixel centers. Unfortunately, I could not figure out how access the correct mip map level. Maybe @fclem knows that.

void point_texco_clamp(vec3 vin, sampler2D ima, out vec3 vout)
{
  vec2 half_texel_size = 0.5 / vec2(textureSize(ima, 0).xy);
  vout = clamp(vin, half_texel_size.xyy, 1.0 - half_texel_size.xyy);
}

The issue seems to be that `point_texco_clamp` assumes lod level 0 when querying the texture size. From what I've read, we can't simply clamp between 0 and 1, because textures are sampled at pixel centers. Unfortunately, I could not figure out how access the correct mip map level. Maybe @fclem knows that. ``` void point_texco_clamp(vec3 vin, sampler2D ima, out vec3 vout) { vec2 half_texel_size = 0.5 / vec2(textureSize(ima, 0).xy); vout = clamp(vin, half_texel_size.xyy, 1.0 - half_texel_size.xyy); } ```

Clément Foucault commented

2020-05-20 17:11:47 +02:00

This is tricky. We could use textureQueryLod for that matter but this is not supported on all target platform.

What I would prefer is to have different samplers objects for each textures and bind the correct one for each texture nodes.

That's too late for 2.83 so I would leave that open to be tackled for 2.90.

This is tricky. We could use textureQueryLod for that matter but this is not supported on all target platform. What I would prefer is to have different samplers objects for each textures and bind the correct one for each texture nodes. That's too late for 2.83 so I would leave that open to be tackled for 2.90.

Enzio Probst commented

2020-06-02 14:10:57 +02:00

Added subscriber: @EnzioProbst

Enzio Probst commented

2020-06-02 14:10:57 +02:00

Another problem with mipmapping happens when using non-continuous texture coordinates like white noise.
I guess the automatic mip level calculation fails as dfdx and dfdy calculation does not make sense for this usage.
This only happens for Linear Interpolation.

Such a setup using white noise can be quite handy for raycasting shaders, blur effects etc.
It would be great to have an option for disabling mipmapping while still doing linear filtering. Would this be supported on all platforms?
Or even better expose a node socket for manually controlling the miplevel. Manual miplevel can also be used for number of effects like cheap blur.
while textureQueryLod is not OpenGL 3.3 textureLod is. So manual control should be doable.

Another problem with mipmapping happens when using non-continuous texture coordinates like white noise. I guess the automatic mip level calculation fails as dfdx and dfdy calculation does not make sense for this usage. This only happens for Linear Interpolation. ![mipmap_non_continous.png](https://archive.blender.org/developer/F8571979/mipmap_non_continous.png) Such a setup using white noise can be quite handy for raycasting shaders, blur effects etc. It would be great to have an option for disabling mipmapping while still doing linear filtering. Would this be supported on all platforms? Or even better expose a node socket for manually controlling the miplevel. Manual miplevel can also be used for number of effects like cheap blur. while `textureQueryLod` is not OpenGL 3.3 `textureLod` is. So manual control should be doable.

blender-admin commented

2020-06-03 16:18:28 +02:00

This issue was referenced by b2dcff4c21

This issue was referenced by b2dcff4c21a645fa16ca39484d206a38944168d2

Clément Foucault commented

2020-06-03 16:24:41 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Clément Foucault closed this issue

2020-06-03 16:24:41 +02:00

Clément Foucault self-assigned this 2020-06-03 16:24:41 +02:00

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Eevee mipmaps not respecting border mode #73942