Noise texture poor precision in Green and Blue color channels #118832

New Issue

Lance Phan · 2024-02-28T06:54:27+01:00

Lance Phan commented

2024-02-28 06:54:27 +01:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.13

Blender Version
Broken: version: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: 9be62e85b727
Worked:
The Red channel works as expected

Short description of error
In large scale (0.01), the green and blue became noticeably jagged

Exact steps for others to reproduce the error
Add a noise texture in the shader editor, use Object texture coordinate
Set the scale of the noise to 0.01
Separate the color output to Red Green and Blue
Use a Greater Than node on the Green or Blue channel, set a threshold to show a clear black and white border
Zoom in to see the jagged edge

The same problem also exists in Blender 3.6

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.13 **Blender Version** Broken: version: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: `9be62e85b727` Worked: The Red channel works as expected **Short description of error** In large scale (0.01), the green and blue became noticeably jagged **Exact steps for others to reproduce the error** Add a noise texture in the shader editor, use Object texture coordinate Set the scale of the noise to 0.01 Separate the color output to Red Green and Blue Use a Greater Than node on the Green or Blue channel, set a threshold to show a clear black and white border Zoom in to see the jagged edge The same problem also exists in Blender 3.6

jagged noise texture.png

126 KiB

Lance Phan added the

labels 2024-02-28 06:54:28 +01:00

Germano Cavalcante commented

2024-02-28 14:29:32 +01:00

Thank you for the report.

I can confirm the issue with the noise texture's poor precision in the green and blue color channels.
Attached is the .blend file I used to test.

This could potentially be a technical limitation of float precision, which can lead to jagged edges in certain color channels. However, it is worth noting that the red channel does not exhibit the same problem.

The issue is seems in both EEVEE and Cycles.

Thank you for the report. I can confirm the issue with the noise texture's poor precision in the green and blue color channels. Attached is the .blend file I used to test. This could potentially be a technical limitation of float precision, which can lead to jagged edges in certain color channels. However, it is worth noting that the red channel does not exhibit the same problem. The issue is seems in both EEVEE and Cycles.

noise_texture_XY_jagged__bug.blend

912 KiB

Germano Cavalcante added

and removed

labels 2024-02-28 14:30:19 +01:00

XDzZyq commented

2024-03-01 05:33:18 +01:00

 #define NOISE_FRACTAL_DISTORTED_3D(NOISE_TYPE) \
 ...
  value = NOISE_TYPE(p, detail, roughness, lacunarity, offset, gain, normalize != 0.0); \
  color = vec4(value, \
               NOISE_TYPE(p + random_vec3_offset(3.0), \
                          detail, \
                          roughness, \
                          lacunarity, \
                          offset, \
                          gain, \
                          normalize != 0.0), \
               NOISE_TYPE(p + random_vec3_offset(4.0), \
                          detail, \
                          roughness, \
                          lacunarity, \
                          offset, \
                          gain, \
                          normalize != 0.0), \
               1.0);

e1023b22f1/source/blender/gpu/shaders/material/gpu_shader_material_tex_noise.glsl (L64-L88)

I noticed only the red channel does not have a random offset. After manually adding up a large float number (e.g. 100.111111f), similar to the range of random_vec3_offset, to the rad channel, the precision problem appears. I believe it is caused by missing precision during float addition.

``` #define NOISE_FRACTAL_DISTORTED_3D(NOISE_TYPE) \ ... value = NOISE_TYPE(p, detail, roughness, lacunarity, offset, gain, normalize != 0.0); \ color = vec4(value, \ NOISE_TYPE(p + random_vec3_offset(3.0), \ detail, \ roughness, \ lacunarity, \ offset, \ gain, \ normalize != 0.0), \ NOISE_TYPE(p + random_vec3_offset(4.0), \ detail, \ roughness, \ lacunarity, \ offset, \ gain, \ normalize != 0.0), \ 1.0); ``` https://projects.blender.org/blender/blender/src/commit/e1023b22f15733c8abe9341aace6eb1b57bbf588/source/blender/gpu/shaders/material/gpu_shader_material_tex_noise.glsl#L64-L88 I noticed only the red channel does not have a random offset. After manually adding up a large float number (e.g. ```100.111111f```), similar to the range of ```random_vec3_offset```, to the rad channel, the precision problem appears. I believe it is caused by missing precision during float addition.

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Noise texture poor precision in Green and Blue color channels #118832