Reading ANY glb with morph targets will crash on iOS platform with backend::Metal

[fishelegs]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. use master branch or v1.3.1 release branch
   2.open hello-gltf iOS demo with Metal
   3.change DamagedHelmet.glb to ANY glb with morph targets.
   4.It'll crash after running.

Expected behavior
No crash.

Screenshots
crash in id PipelineStateCreator::operator()(id device,
const PipelineState& state) noexcept ;
error:
Error Domain=AGXMetalA10 Code=3 "Cannot convert attribute from MTLAttributeFormatChar4 to an unsigned integer type" UserInfo={NSLocalizedDescription=Cannot convert attribute from MTLAttributeFormatChar4 to an unsigned integer type}

Callstack:
2019-08-15 20:51:34.426728+0800 hello-gltf[12459:583455] Compiler failed to build request
Cannot convert attribute from MTLAttributeFormatChar4 to an unsigned integer type
utils::PostconditionPanic
in id filament::backend::metal::PipelineStateCreator::operator()(id, const filament::backend::metal::PipelineState &):85
in file filament/backend/src/metal/MetalState.mm
reason: Could not create Metal pipeline state.
#0 0 hello-gltf 0x0000000104adb710 _ZN5utils9CallStack6updateEm + 32
#1 0 hello-gltf 0x0000000104af59bc _ZN5utils6TPanicINS_18PostconditionPanicEEC2EPKcS4_iNSt3__112basic_stringIcNS5_11char_traitsIcEENS5_9allocatorIcEEEE + 192
#2 0 hello-gltf 0x0000000104af695c _ZN5utils18PostconditionPanicCI2NS_6TPanicIS0_EEEPKcS3_iNSt3__112basic_stringIcNS4_11char_traitsIcEENS4_9allocatorIcEEEE + 68
#3 0 hello-gltf 0x0000000104af5590 _ZN5utils18PostconditionPanicCI1NS_6TPanicIS0_EEEPKcS3_iNSt3__112basic_stringIcNS4_11char_traitsIcEENS4_9allocatorIcEEEE + 52
#4 0 hello-gltf 0x0000000104af5490 _ZN5utils6TPanicINS_18PostconditionPanicEE5panicEPKcS4_iS4_z + 240
#5 0 hello-gltf 0x0000000104ab7aa0 _ZN8filament7backend5metal20PipelineStateCreatorclEPU19objcproto9MTLDevice11objc_objectRKNS1_13PipelineStateE + 2000
#6 0 hello-gltf 0x0000000104a8c1a0 ZN8filament7backend5metal10StateCacheINS1_13PipelineStateEPU33objcproto22MTLRenderPipelineState11objc_objectNS1_20PipelineStateCreatorEE16getOrCreateStateERKS3 + 184
#7 0 hello-gltf 0x0000000104a766c4 _ZN8filament7backend5metal11MetalDriver4drawENS0_13PipelineStateENS0_6HandleINS0_17HwRenderPrimitiveEEE + 616
#8 0 hello-gltf 0x0000000104aa1454 _ZN8filament7backend10trampolineIMNS0_5metal11MetalDriverEFvNS0_13PipelineStateENS0_6HandleINS0_17HwRenderPrimitiveEEEERS3_RNSt3__15tupleIJS4_S7_EEEJLm0ELm1EEEEvOT_OT0_OT1_NSB_16integer_sequenceImJXspT2_EEEE + 236
#9 0 hello-gltf 0x0000000104aa1348 ZN8filament7backend5applyIMNS0_5metal11MetalDriverEFvNS0_13PipelineStateENS0_6HandleINS0_17HwRenderPrimitiveEEEERS3_RNSt3__15tupleIJS4_S7_EEEEEvOT_OT0_OT1 + 88
#10 0 hello-gltf 0x0000000104a76444 _ZN8filament7backend11CommandTypeIJMNS0_6DriverEFvNS0_13PipelineStateENS0_6HandleINS0_17HwRenderPrimitiveEEEEEE7CommandIXadL_ZNS2_4drawES3_S6_EEE7executeIMNS0_5metal11MetalDriverEFvS3_S6_ERSE_EEvOT_OT0_PNS0_11CommandBaseEPl + 120
#11 0 hello-gltf 0x0000000104a72614 _ZN8filament7backend18ConcreteDispatcherINS0_5metal11MetalDriverEE4drawERNS0_6DriverEPNS0_11CommandBaseEPl + 72
#12 0 hello-gltf 0x0000000104a16870 _ZN8filament7backend11CommandBase7executeERNS0_6DriverE + 64
#13 0 hello-gltf 0x0000000104a16788 _ZN8filament7backend13CommandStream7executeEPv + 164
#14 0 hello-gltf 0x0000000104951c48 _ZN8filament7details7FEngine7executeEv + 188
#15 0 hello-gltf 0x000000010494d3f4 _ZN8filament7details7FEngine4loopEv + 516
#16 0 hello-gltf 0x0000000104966b60 ZNSt3__1L8__invokeIMN8filament7details7FEngineEFivEPS3_JEvEEDTcldsdeclsr3std3__1E7forwardIT0_Efp0_Efp_spclsr3std3__1E7forwardIT1_Efp1_EEEOT_OS7_DpOS8 + 128
#17 0 hello-gltf 0x0000000104966a58 _ZNSt3__1L16__thread_executeINS_10unique_ptrINS_15__thread_structENS_14default_deleteIS2_EEEEMN8filament7details7FEngineEFivEJPS8_EJLm2EEEEvRNS_5tupleIJT_T0_DpT1_EEENS_15__tuple_indicesIJXspT2_EEEE + 68
libc++abi.dylib: terminating with uncaught exception of type utils::PostconditionPanic
Printing description of error:
Error Domain=AGXMetalA10 Code=3 "Cannot convert attribute from MTLAttributeFormatChar4 to an unsigned integer type" UserInfo={NSLocalizedDescription=Cannot convert attribute from MTLAttributeFormatChar4 to an unsigned integer type}

Desktop (please complete the following information):

• OS:iOS
• GPU: PowerVR / Apple GPU
• Backend: Metal

Smartphone (please complete the following information):

• Device: all iPhone
• OS: iOS 12

Additional context
glb with morph targets.
DamagedHelmet.glb.zip

[bejado]

Thanks for the report, I'm able to reproduce. Note that on iOS, OpenGL crashes as well. On desktop, Metal crashes for the same reason, and OpenGL fails to render anything.

[prideout]

OpenGL looks ok to me on macOS

[bejado]

Ah yes, desktop OpenGL does work, I was seeing a separate issue related to IBLs / sunlight.

[bejado]

As a quick workaround, you could replace the MTLVertexFormatChar4 here with MTLVertexFormatUChar4.