save and restore uniform buffer bindings during batch renderer selection #291

mattyjams · 2020-02-19T02:53:20Z

This addresses an issue when running the testProxyShapeSelectionPerformance test where only the first image would be drawn correctly and all images drawn after the first selection operation would be completely black.

This workaround was already being used during rendering, but this change applies it during selection as well.

mattyjams · 2020-02-19T19:28:03Z

Actually, I just saw that this was turned into an RAII class in mayaToHydra:
https://github.com/Autodesk/maya-usd/blob/dev/lib/render/mayaToHydra/renderOverride.cpp#L110

Maybe it'd be better if I moved that to a public place (px_vp20/utils.h?) and used it from there instead? I'll try that and update the branch.

huidong-chen · 2020-02-19T20:02:22Z

lib/render/pxrUsdMayaGL/batchRenderer.cpp

@@ -1129,6 +1136,27 @@ UsdMayaGLBatchRenderer::_TestIntersection(
                 GL_TEXTURE_BIT |
                 GL_POLYGON_BIT);

+    // XXX: When Maya is using OpenGL Core Profile as the rendering engine (in


To help me understand better, when is _TestIntersection() called?

Is UsdMayaGLBatchRenderer being called from the draw override solution from Pixar?

Yeah, UsdMayaGLBatchRenderer is used to image pxrUsdProxyShape and mayaUsdProxyShape when VP2_RENDER_DELEGATE_PROXY is disabled.

The MPxDrawOverride::userSelect() override for proxy shapes is what ends up eventually calling _TestIntersection() to do viewport-based picking:

maya-usd/lib/render/pxrUsdMayaGL/proxyDrawOverride.cpp

Line 259 in c75e696

UsdMayaProxyDrawOverride::userSelect(

huidong-chen · 2020-02-19T20:17:08Z

lib/render/pxrUsdMayaGL/batchRenderer.cpp

+    // across Hydra calls. We try not to bog down performance by saving and
+    // restoring *all* GL_MAX_UNIFORM_BUFFER_BINDINGS possible bindings, so
+    // instead we only do just enough to avoid issues. Empirically, the
+    // problematic binding has been the material binding at index 4.


Looks like this would only affect selection performance? Any other workflow that would be impacted?

The one other workflow that might be affected is when live surface is used. We end up using Hydra to do the intersection testing for that as well:

maya-usd/lib/render/pxrUsdMayaGL/proxyShapeDelegate.cpp

Line 96 in c75e696

bool didIsect = renderer.TestIntersectionCustomPrimFilter(

mattyjams · 2020-02-19T23:13:31Z

I just pushed a re-worked version of this where the UBOBindingsSaver was moved to px_vp20/utils and both mayaToHydra and the Pixar batch renderer use it from there.

mattyjams · 2020-02-19T23:18:50Z

lib/render/pxrUsdMayaGL/batchRenderer.cpp

@@ -1196,6 +1198,8 @@ UsdMayaGLBatchRenderer::_ComputeSelection(

    _selectResults.clear();

+    UBOBindingsSaver bindingsSaver;


This version is slightly different from the previous version in that the instantiation of the UBOBindingsSaver happens outside of _TestIntersection(). In relatively infrequent cases, the loop below may go through more than one iteration, so this avoids repeatedly saving and restoring the bindings on each iteration.

This is also why a UBOBindingsSaver was needed in TestIntersectionCustomPrimFilter() above as well.

The original version of this PR is available for comparison in commit 37d2924fb875037539ac38a13034d052606d0ff1.

mattyjams · 2020-02-19T23:28:13Z

Here's the simple test scene I was using for this:
CubeModelProxy.zip

Extract that archive and launch Maya on the ma file with VP2_RENDER_DELEGATE_PROXY=0 (disabled).

Then I had this incantation in the script editor (distilled from the unit test script mentioned in the description):

import os

testDir = os.path.abspath('.')

cmds.workspace(testDir, o=True)


def _WriteViewportImage(outputImageName):
    cmds.setAttr('defaultRenderGlobals.currentRenderer', 'mayaHardware2', type='string')
    # Set the image format to PNG.
    cmds.setAttr('defaultRenderGlobals.imageFormat', 32)
    # Set the render mode to shaded and textured.
    cmds.setAttr('hardwareRenderingGlobals.renderMode', 4)
    # Specify the output image prefix. The path to it is built from the
    # workspace directory.
    cmds.setAttr('defaultRenderGlobals.imageFilePrefix', outputImageName, type='string')
    # Apply the viewer's color transform to the rendered image, otherwise
    # it comes out too dark.
    cmds.setAttr("defaultColorMgtGlobals.outputTransformEnabled", 1)
    # Do the render.
    cmds.ogsRender(camera='persp', currentFrame=True, width=960, height=540)

_WriteViewportImage('testImage1')

# Click on the cube in the viewport to select it here

_WriteViewportImage('testImage2')

Without these changes, I was seeing testImage2.png coming out completely black. With the changes, it shows the selected cube instead.

mattyjams · 2020-02-19T23:45:43Z

For what it's worth, it looks like the underlying issue is something that Animal Logic ended up tripping over as well:

maya-usd/plugin/al/lib/AL_USDMaya/AL/usdmaya/nodes/ProxyDrawOverride.cpp

Line 464 in c75e696

    
           // HACK: Maya doesn't restore this ONE buffer binding after our override is done so we have to do it for them.

huidong-chen · 2020-02-20T00:28:19Z

lib/render/px_vp20/utils.h

+/// possible bindings, so instead we only do just enough to avoid issues.
+/// Empirically, the problematic binding has been the material binding at
+/// index 4.
+class UBOBindingsSaver


Does it make sense to add a GL post fix to the class name? I think this makes it clearer that the class is GL-specific.

Yeah, makes sense. The name is a little opaque at a quick glance.

How does GLUniformBufferBindingsSaver sound?

huidong-chen · 2020-02-20T03:39:52Z

@mattyjams Thanks for making this into a utilities class that can be used elsewhere.

lib/render/px_vp20/utils.cpp

This workaround was originally extracted from the Pixar batch renderer and turned into a more convenient and reusable RAII-style class. Since the workaround it provides is needed in multiple places, it would be good to have it defined publicly to take advantage of that reuse.

With UBOBindingsSaver now available from px_vp20/utils, this change uses that class to wrap the Hydra Execute() call made during rendering.

Uniform buffer bindings need to be saved and restored across Hydra Execute() calls as a workaround to the issue described in the documentation for the UBOBindingsSaver class. There are two such calls in the Pixar batch renderer, one during drawing, and another in the private _TestIntersection() method which is used when computing selections and during live surface workflows. The former was already protected by the workaround, but the latter was not, so this change applies the workaround there as well.

kxl-adsk · 2020-02-20T18:02:16Z

Which commit fixed it?

mattyjams · 2020-02-20T18:26:40Z

I made the fix as part of an interactive rebase, so the export macros were added in commit 32def62.

lib/render/px_vp20/utils.h

kxl-adsk requested a review from huidong-chen February 19, 2020 18:58

huidong-chen reviewed Feb 19, 2020

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mattyjams force-pushed the pr/batch_renderer_selection_uniform_buffer_binding_workaround branch from 37d2924 to 0705c2c Compare February 19, 2020 23:11

mattyjams commented Feb 19, 2020

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huidong-chen reviewed Feb 20, 2020

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huidong-chen self-requested a review February 20, 2020 03:34

huidong-chen approved these changes Feb 20, 2020

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lib/render/px_vp20/utils.cpp Show resolved Hide resolved

mattyjams added 4 commits February 20, 2020 09:54

use UBOBindingsSaver when rendering in Pixar's batch renderer

35a6a0f

With UBOBindingsSaver now available from px_vp20/utils, this change uses that class to wrap the Hydra Execute() call made during rendering.

rename UBOBindingsSaver class to GLUniformBufferBindingsSaver

80bf6f8

mattyjams force-pushed the pr/batch_renderer_selection_uniform_buffer_binding_workaround branch from 982acd5 to 80bf6f8 Compare February 20, 2020 17:57

huidong-chen reviewed Feb 20, 2020

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lib/render/px_vp20/utils.h Outdated Show resolved Hide resolved

make UNIFORM_BINDINGS_TO_SAVE private to the class

5c448b5

kxl-adsk approved these changes Feb 20, 2020

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kxl-adsk merged commit 77c1585 into Autodesk:dev Feb 20, 2020

mattyjams deleted the pr/batch_renderer_selection_uniform_buffer_binding_workaround branch February 20, 2020 21:52

mattyjams mentioned this pull request Mar 4, 2020

[EMSUSD-53] hitTest command fails when using VP2.0 render delegate #257

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save and restore uniform buffer bindings during batch renderer selection #291

save and restore uniform buffer bindings during batch renderer selection #291

mattyjams commented Feb 19, 2020

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huidong-chen Feb 19, 2020

mattyjams Feb 19, 2020

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mattyjams Feb 19, 2020

mattyjams commented Feb 19, 2020

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mattyjams Feb 20, 2020

huidong-chen commented Feb 20, 2020

kxl-adsk commented Feb 20, 2020

mattyjams commented Feb 20, 2020

		@@ -1196,6 +1198,8 @@ UsdMayaGLBatchRenderer::_ComputeSelection(

		_selectResults.clear();

		UBOBindingsSaver bindingsSaver;

save and restore uniform buffer bindings during batch renderer selection #291

save and restore uniform buffer bindings during batch renderer selection #291

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