87 lines
No EOL
3.4 KiB
Markdown
87 lines
No EOL
3.4 KiB
Markdown
# Morph Stress Test
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## Tags
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[core](../../Models-core.md), [testing](../../Models-testing.md)
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## Summary
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Tests up to 8 morph targets.
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## Operations
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* [Display](https://github.khronos.org/glTF-Sample-Viewer-Release/?model=https://raw.GithubUserContent.com/KhronosGroup/glTF-Sample-Assets/main/./Models/MorphStressTest/glTF-Binary/MorphStressTest.glb) in SampleViewer
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* [Download GLB](https://raw.GithubUserContent.com/KhronosGroup/glTF-Sample-Assets/main/./Models/MorphStressTest/glTF-Binary/MorphStressTest.glb)
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* [Model Directory](./)
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## Screenshot
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## Description
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This model has a base mesh, plus eight morph targets. The base and each of the morph targets has
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both a POSITION and a NORMAL accessor, resulting in no less than 18 vertex attributes being requested
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by a typical implementation. This number can be too high for many realtime graphics systems, and
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the client runtime may take steps to limit the overall number of morph targets and/or limit the
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number of active morph targets.
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As such, this model is not expected to render correctly everywhere. Instead, it pushes the limits
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to see how many morph targets can move at once before problems become apparent.
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## Animations
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Three animations are included:
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---
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### "Individuals"
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Each morph target is exercised one at a time, and returns to zero strength before the next one
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starts to move. This offers runtimes the best chance of success, as vertex attributes need only
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be allocated for one morph target at a time. Even so, systems that pre-allocate morph target
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attributes may place an upper limit here, allowing only some of the test blocks to move.
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---
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### "TheWave"
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This animation tests a wave of morph targets being activated simultaneously. This does require
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a high number of vertex attributes to be available. If glitches in movement are observed,
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continue on to the "Pulse" animation for closer inspection.
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### "Pulse"
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This is the most stressful test, with all 8 morph targets reaching full strength before any
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begin to subside. Some runtimes may place limits on how many morph targets can be active at
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once, resulting in a distinctive visual pattern here: Only the first N test blocks will
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appear to move, where N is the number of simultaneous active morph targets allowed. Test
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blocks on the right will remain frozen in the starting position until the first few blocks
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on the left have returned to rest. After the blocks on the left have returned to rest, they
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could relinquish their vertex attributes to blocks on the right, allowing those blocks to
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"catch up" to their assigned positions in the animation.
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It is also possible that there could be a hard limit on the number of morph targets, regardless
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of whether they are active or not. In this case, only the first N blocks will move at all,
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and the remainder will be frozen the entire time.
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---
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## Implementation Notes
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BabylonJS has shared some technical details of their "Infinite Morph Targets" implementation
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in [this YouTube video](https://www.youtube.com/watch?v=LBPRmGgU0PE).
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## Legal
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© 2021, Analytical Graphics, Inc.. [CC BY 4.0 International](https://creativecommons.org/licenses/by/4.0/legalcode)
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- Ed Mackey for Everything
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#### Assembled by modelmetadata |