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Differential D5437

Show Background Image Beneath Transparent Objects (Cycles only)
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Authored by Jeroen Bakker (jbakker) on Aug 8 2019, 12:53 PM.

Details

Reviewers
Clément Foucault (fclem)
Maniphest Tasks
T65988: When rendering in viewport mode the draw engines do not pass correct Alpha values.
Commits
rB0bdf4e2f2d1c: Show Background Image Beneath Transparent Objects (Cycles only)
Summary

Camera background images were not shown beneath transparent objects.
This patch performs an alpha under for background images for cycles.

In order to see the difference the Film transparency needs to be turned on.

Note that workbench and EEVEE still needs to be adapted as they don't
write the alpha value in the viewport.

This image shows the old behavior (left) vs the new behavior (right)

Side note. This implementation is already an improvement of the current behavior, what users are requesting. (Show background images underneath cycles viewport rendering.) It is clear that this patch still needs to be extended to workbench and eevee. For now that should be marked as a known limitation.

Diff Detail

Repository
rB Blender
Branch
T65988 (branched from master)
Build Status
Buildable 4334
Build 4334: arc lint + arc unit

Event Timeline

Jeroen Bakker (jbakker) created this revision.Aug 8 2019, 12:53 PM
Harbormaster completed remote builds in B4334: Diff 16942.Aug 8 2019, 12:53 PM
Jeroen Bakker (jbakker) edited the summary of this revision. (Show Details)Aug 8 2019, 12:58 PM
Jeroen Bakker (jbakker) planned changes to this revision.Aug 8 2019, 1:38 PM
  • alpha channel of source image is ignored. Add a shader that does premultiply the colors with the alpha
Jeroen Bakker (jbakker) updated this revision to Diff 16943.Aug 8 2019, 1:57 PM

Use Alpha premul for camera images

Harbormaster completed remote builds in B4335: Diff 16943.Aug 8 2019, 1:57 PM
Jeroen Bakker (jbakker) retitled this revision from Show Background Image Beneath Transparent Objects to [WIP] Show Background Image Beneath Transparent Objects.Aug 8 2019, 2:05 PM
Jeroen Bakker (jbakker) planned changes to this revision.Aug 9 2019, 10:22 AM

Move the drawing of the checkerboard to object_mode.

Jeroen Bakker (jbakker) updated this revision to Diff 16979.Aug 9 2019, 11:30 AM

Postpone rendering of checkerboard for better compositing

Harbormaster completed remote builds in B4350: Diff 16979.Aug 9 2019, 11:30 AM
Jeroen Bakker (jbakker) edited the summary of this revision. (Show Details)Aug 9 2019, 11:32 AM
Jeroen Bakker (jbakker) updated this revision to Diff 16980.Aug 9 2019, 11:37 AM

Removed unused code

Harbormaster completed remote builds in B4351: Diff 16980.Aug 9 2019, 11:37 AM
Jeroen Bakker (jbakker) updated this revision to Diff 16981.Aug 9 2019, 11:39 AM

Added f back

Harbormaster completed remote builds in B4352: Diff 16981.Aug 9 2019, 11:39 AM
Dalai Felinto (dfelinto) added a subscriber: Dalai Felinto (dfelinto).Sep 5 2019, 8:56 PM

@Jeroen Bakker (jbakker) what is the current status of this patch? Trying to see if it may fit in 2.81 (it seems a bit late for that though to be honest).

Jeroen Bakker (jbakker) added a comment.Sep 6 2019, 8:51 AM

Part of the issues has been resolved inside as in it works better than it currently does. It works with cycles, but only with a single background image. EEVEE and Workbench still needs to be adapted as they do not support alpha film in the viewport. Supporting multiple background is a OIT question. The non transparent part needs to be rendered front to back. and the transparent part needs to be rendered back to front for better result. The draw engines are a bit in between and can intervene.

IMO it is solvable to 95% of what we want.

Jeroen Bakker (jbakker) updated this revision to Diff 18099.Sep 11 2019, 2:57 PM

Draw order for alpha under pass

Harbormaster completed remote builds in B4907: Diff 18099.Sep 11 2019, 2:57 PM
Jeroen Bakker (jbakker) updated this revision to Diff 18366.Sep 19 2019, 1:59 PM

Finalized for cycles

Harbormaster completed remote builds in B5032: Diff 18366.Sep 19 2019, 1:59 PM
Jeroen Bakker (jbakker) retitled this revision from [WIP] Show Background Image Beneath Transparent Objects to Show Background Image Beneath Transparent Objects.Sep 19 2019, 2:07 PM
Jeroen Bakker (jbakker) edited the summary of this revision. (Show Details)
Jeroen Bakker (jbakker) added a reviewer: Clément Foucault (fclem).
Jeroen Bakker (jbakker) added a project: GPU / Viewport.
Jeroen Bakker (jbakker) retitled this revision from Show Background Image Beneath Transparent Objects to Show Background Image Beneath Transparent Objects (Cycles only).
Sebastian Koenig (sebastian_k) added a subscriber: Sebastian Koenig (sebastian_k).Sep 19 2019, 2:14 PM
Dalai Felinto (dfelinto) added inline comments.Sep 19 2019, 3:03 PM
source/blender/draw/modes/object_mode.c
1341

Nitpicking, but this is float promotion, and some compilers will throw annoying warnings at us ;)

- depth = 0.000001;
+ depth = 0.000001f;
1347
- depth = 0.999999;
+ depth = 0.999999f;

Personally I would initialize float depth = 0.000001f, and here do depth = 1.0f - depth.

Jeroen Bakker (jbakker) mentioned this in T57739: WireFrame Mode excludes the backGround Image.Sep 20 2019, 3:16 PM
Jeroen Bakker (jbakker) updated this revision to Diff 18490.Sep 25 2019, 4:05 PM

Float conversions

Harbormaster completed remote builds in B5094: Diff 18490.Sep 25 2019, 4:05 PM
Jeroen Bakker (jbakker) marked 2 inline comments as done.Sep 25 2019, 4:05 PM
Clément Foucault (fclem) requested changes to this revision.Oct 2 2019, 6:14 PM

That said, I don't think the 2 pass approach is necessary. Is there any reason behind it? if any, it should at least be mentioned somewhere in a comment.

source/blender/draw/modes/object_mode.c
1353

I'm really not a big fan of this. Another approach would be to cycle through the CameraBGImage backwards in another loop.

It won't cost anything and it makes things more clean IMO. One loop for foreground and one for background images.

1554

Why not use :

DRWState state = DRW_STATE_WRITE_COLOR;
psl->camera_images_back = DRW_pass_create("Camera Images Back",
                                          state | DRW_STATE_BLEND_ALPHA_UNDER_PREMUL);
psl->camera_images_front = DRW_pass_create("Camera Images Front",
                                           state | DRW_STATE_BLEND_ALPHA_PREMUL);

This simplify a lot of thing. No need for double pass drawing, no need for depth biasing.

This revision now requires changes to proceed.Oct 2 2019, 6:14 PM
Jeroen Bakker (jbakker) updated this revision to Diff 18781.Oct 4 2019, 1:01 PM

Removed the reverse add in draw manager

Harbormaster completed remote builds in B5236: Diff 18781.Oct 4 2019, 1:01 PM
Jeroen Bakker (jbakker) marked an inline comment as done.Oct 4 2019, 1:01 PM
Clément Foucault (fclem) accepted this revision.Oct 4 2019, 4:35 PM
This revision is now accepted and ready to land.Oct 4 2019, 4:35 PM
Closed by commit rB0bdf4e2f2d1c: Show Background Image Beneath Transparent Objects (Cycles only) (authored by Jeroen Bakker (jbakker)). · Explain WhyOct 5 2019, 5:20 PM
This revision was automatically updated to reflect the committed changes.
Jeroen Bakker (jbakker) added a commit: rB0bdf4e2f2d1c: Show Background Image Beneath Transparent Objects (Cycles only).

Revision Contents
Changeset List

PathSize
source/
blender/
draw/
intern/
1 line
9 lines
2 lines
modes/
45 lines
gpu/
1 line
intern/
9 lines

Diff 16942

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source/blender/draw/intern/DRW_render.h

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source/blender/draw/intern/draw_manager_exec.c

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source/blender/draw/intern/draw_view.c

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source/blender/draw/modes/object_mode.c

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source/blender/gpu/GPU_immediate_util.h

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source/blender/gpu/intern/gpu_immediate_util.c

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