Fix T85312: Volumes have an offset in Workbench, Eevee and Cycles.
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Authored by Jacques Lucke (JacquesLucke) on Feb 3 2021, 7:38 PM.

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Reviewers

Brecht Van Lommel (brecht)
Clément Foucault (fclem)

Maniphest Tasks

T85312: Volumes have an offset in viewport, Eevee and Cycles.

Summary

I had to change a few more places than I've thought at first, unfortunately.

This seems to fix the behavior for Workbench, Eevee and Cycles.

The patch can be tested with this file. It uses a temporary change in the Mesh to Volume modifier that makes it output a single voxel every time.

volume_offset.blend760 KBDownload

The voxel should be centered at the world origin:

Diff Detail

Repository

rB Blender

Branch

volume-offset (branched from master)

Build Status

Buildable 12723
Build 12723: arc lint + arc unit

Event Timeline

Jacques Lucke (JacquesLucke) requested review of this revision.Feb 3 2021, 7:38 PM

Jacques Lucke (JacquesLucke) created this revision.

Harbormaster completed remote builds in B12584: Diff 33501.Feb 3 2021, 7:38 PM

Jacques Lucke (JacquesLucke) added a task: T85312: Volumes have an offset in viewport, Eevee and Cycles..Feb 3 2021, 7:38 PM

Jacques Lucke (JacquesLucke) edited the summary of this revision. (Show Details)Feb 3 2021, 7:45 PM

Jacques Lucke (JacquesLucke) mentioned this in T85312: Volumes have an offset in viewport, Eevee and Cycles..Feb 3 2021, 7:50 PM

cleanup

Harbormaster completed remote builds in B12723: Diff 33723.Feb 8 2021, 6:34 PM

Jacques Lucke (JacquesLucke) retitled this revision from Fix T85312: Volumes have an offset in viewport, Eevee and Cycles (WIP). to Fix T85312: Volumes have an offset in viewport, Eevee and Cycles..Feb 8 2021, 6:48 PM

Jacques Lucke (JacquesLucke) edited the summary of this revision. (Show Details)

Jacques Lucke (JacquesLucke) retitled this revision from Fix T85312: Volumes have an offset in viewport, Eevee and Cycles. to Fix T85312: Volumes have an offset in Workbench, Eevee and Cycles..Feb 8 2021, 6:51 PM

Jacques Lucke (JacquesLucke) added reviewers: Brecht Van Lommel (brecht), Clément Foucault (fclem).Feb 8 2021, 6:53 PM

Jacques Lucke (JacquesLucke) added inline comments.

source/blender/modifiers/intern/MOD_mesh_to_volume.cc
258	I won't commit this part, but it is very useful to see if the patch is actually working.

Clément Foucault (fclem) added inline comments.Feb 8 2021, 9:37 PM

source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
18	Can't you use a `GPU_SAMPLER_CLAMP_BORDER` (using `GPU_texture_wrap_mode(false, false)`)? Border color is vec4(0,0,0,1) by default.

Jacques Lucke (JacquesLucke) added inline comments.Feb 9 2021, 12:15 PM

source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
18	Unfortunately, this does not seem to work (although I also don't know what these clamping modes do exactly). Using P1950 on top of this patch results in It seems to clamp on different values than 0 and 1. I should note that this is related to the fact that `BKE_volume_grid_bounds` does not return the best possible bounding , because it uses `evalLeafBoundingBox` instead of `evalActiveVoxelBoundingBox` (the latter of which results in a more accurate bounding box but is more costly). An alternative fix would be to change `BKE_volume_grid_bounds`, but I found that the drawing code should be correct even if this function returns a non-optimal bounding box.

Clément Foucault (fclem) accepted this revision.Feb 13 2021, 1:42 PM

Clément Foucault (fclem) added inline comments.

source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
18	You are right the texture might interpolate until -0.5/textureSize. Then forget about the sampler trick. However you can check out of bounds like this to aviod the double check: any(greaterThan(abs(coord - 0.5), vec3(0.5)))

This revision is now accepted and ready to land.Feb 13 2021, 1:42 PM

cleanup check

Harbormaster completed remote builds in B12892: Diff 33989.Feb 15 2021, 11:08 AM

Jacques Lucke (JacquesLucke) added inline comments.Feb 15 2021, 11:08 AM

source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
18	That makes sense. There is similar check in `volume_frag.glsl` with can be simplified as well, that should be done in a separate patch though.

Clément Foucault (fclem) accepted this revision.Feb 15 2021, 12:08 PM

Brecht Van Lommel (brecht) requested changes to this revision.Feb 15 2021, 2:56 PM

Brecht Van Lommel (brecht) added inline comments.

intern/cycles/render/image_vdb.cpp
150–152	It seems the NanoVDB code path was not fixed, we use that by default for releases.

This revision now requires changes to proceed.Feb 15 2021, 2:56 PM

Jacques Lucke (JacquesLucke) added inline comments.Feb 15 2021, 3:51 PM

intern/cycles/render/image_vdb.cpp
150–152	Ah right, didn't test the NanoVDB path yet. I just noticed that both code paths result in different renders without this patch! NanoVDB seems to draw voxels a bit larger (in the image it looks like it is even larger than the computed bounding mesh). With NanoVDB: Without NanoVDB: Will need to look at this in more detail.