Post B9p7QKkbPMG2948seO by uncanny_static@chaos.social
 (DIR) More posts by uncanny_static@chaos.social
 (DIR) Post #B9nTEt1Vxy5Vdn4zyq by mntmn@mastodon.social
       1 likes, 1 repeats
       
       very curious mesa problem that's been haunting me for a while, and becomes very visible here: when i look at this file (reform next laptop assembly) in blender 5 on my qcs8550 mnt reform next (freedreno), using native OpenGL, most of the components have mangled coordinates/rotations (screenshots 1+2). but when i use Zink (vulkan emulated OpenGL), all is fine.GL experts, what's your take on how this could be caused? is blender using shaders for transforms somehow, and those can be broken?
       
 (DIR) Post #B9no67jS0amlgqIFEm by mntmn@mastodon.social
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       @lritter any hunches perhaps?
       
 (DIR) Post #B9noG1P8ODMWxdVgoa by Perrin42@mastodon.social
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       @mntmn @lritter Notre Dame?
       
 (DIR) Post #B9noep1ZYUMrnwJacK by lritter@mastodon.gamedev.place
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       @mntmn i bet i have followers who understand this better than i do
       
 (DIR) Post #B9p7QKkbPMG2948seO by uncanny_static@chaos.social
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       @mntmn I mean, the driver has to transfer the transformation matrix to the right location in the GPU memory before the vertex shader runs. There might be a race condition or the location is wrong. OpenGL is a state machine, meaning that the driver has to decide which parts in the GPU memory have to be updated and when. Something might go wrong there.If it only happens in Blender, it could also be a bug that is caused by using undefined behavior.
       
 (DIR) Post #B9pOAus92UtGlIu8G0 by mntmn@mastodon.social
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       @uncanny_static this is a very interesting thought, thanks. could also be that something is scribbling over the data, or data alignment issues. but that gives me ideas of where to look
       
 (DIR) Post #B9phOMxxnRo2mrkq3M by karolherbst@chaos.social
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       @mntmn probably filing a bug would be the right course of action, but identifying a bug inside blender can be... rough.Though yeah, looks like vertex coordinates are somehow messed up and I guess it's either synchronization (though than it would have some randomness to it, sometimes) or some weird obscure driver bug, which is possible.
       
 (DIR) Post #B9pkLiWjTegseORbsm by mntmn@mastodon.social
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       @karolherbst hey, thanks for your comment! i think it might be a freedreno opengl bug because this doesn't happen on previous gen (adreno 643) vs adreno 740, and perhaps turnip works a bit differently (which would be used in the zink case)?
       
 (DIR) Post #B9pkUAq06PSGltUOfI by karolherbst@chaos.social
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       @mntmn yeah.. in Mesa most of the GL and VK drivers do not share state management or command buffer creation code, so there to be a difference between the drivers can easily happen.They share a lot of other things, just not that part.