100 lines
4.0 KiB
ReStructuredText
100 lines
4.0 KiB
ReStructuredText
.. default-domain:: C
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Troubleshooting
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================================================================================
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It is possible that sometimes you may get crashes or wrong results.
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Follow these topics
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Memory Allocation:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Again, **cglm** doesn't alloc any memory on heap.
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cglm functions works like memcpy; it copies data from src,
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makes calculations then copy the result to dest.
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You are responsible for allocation of **src** and **dest** parameters.
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Alignment:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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**vec4** and **mat4** types requires 16 byte alignment.
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These types are marked with align attribute to let compiler know about this
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requirement.
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But since MSVC (Windows) throws the error:
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**"formal parameter with requested alignment of 16 won't be aligned"**
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The alignment attribute has been commented for MSVC
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.. code-block:: c
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#if defined(_MSC_VER)
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# define CGLM_ALIGN(X) /* __declspec(align(X)) */
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#else
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# define CGLM_ALIGN(X) __attribute((aligned(X)))
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#endif.
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So MSVC may not know about alignment requirements when creating variables.
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The interesting thing is that, if I remember correctly Visual Studio 2017
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doesn't throw the above error. So we may uncomment that line for Visual Studio 2017,
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you may do it yourself.
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**This MSVC issue is still in TODOs.**
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**UPDATE:** By starting v0.4.5 cglm provides an option to disable alignment requirement.
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Also alignment is disabled for older msvc verisons as default. Now alignment is only required in Visual Studio 2017 version 15.6+ if CGLM_ALL_UNALIGNED macro is not defined.
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Crashes, Invalid Memory Access:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Probably you are trying to write to invalid memory location.
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You may used wrong function for what you want to do.
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For instance you may called **glm_vec4_** functions for **vec3** data type.
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It will try to write 32 byte but since **vec3** is 24 byte it should throw
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memory access error or exit the app without saying anything.
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**UPDATE - IMPORTANT:**
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| On MSVC or some other compilers, if alignment is enabled (default) then double check alignment requirements if you got a crash.
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| If you send GLM_VEC4_ONE or similar macros directly to a function, it may be crashed.
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| Because compiler may not apply alignment as defined on **typedef** to that macro while passing it (on stack) to a function.
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Wrong Results:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Again, you may used wrong function.
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For instance if you use **glm_normalize()** or **glm_vec3_normalize()** for **vec4**,
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it will assume that passed param is **vec3** and will normalize it for **vec3**.
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Since you need to **vec4** to be normalized in your case, you will get wrong results.
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Accessing vec4 type with vec3 functions is valid, you will not get any error, exception or crash.
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You only get wrong results if you don't know what you are doing!
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So be carefull, when your IDE (Xcode, Visual Studio ...) tried to autocomplete function names, READ IT :)
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**Also implementation may be wrong please let us know by creating an issue on Github.**
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BAD_ACCESS : Thread 1: EXC_BAD_ACCESS (code=EXC_I386_GPFLT) or Similar Errors/Crashes
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This is similar issue with alignment. For instance if you compiled **cglm** with
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AVX (**-mavx**, intentionally or not) and if you use **cglm** in an environment that doesn't
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support AVX (or if AVX is disabled intentionally) e.g. environment that max support SSE2/3/4,
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then you probably get **BAD ACCESS** or similar...
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Because if you compile **cglm** with AVX it aligns **mat4** with 32 byte boundary,
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and your project aligns that as 16 byte boundary...
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Check alignment, supported vector extension or simd in **cglm** and linked projects...
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Other Issues?
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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**Please let us know by creating an issue on Github.**
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