Optional triangle vertex array normals generation

[dolphineye]

Hi,

In our project, we don't need normals for raycasting and we don't use rigid body simulations. The computation of normals incur performance and memory usage overhead.

At first, we tried to copy all the stuff related to concave meshes, but we ended up in copying a lot of code for a tiny change.

I'm submitting this pull request to make the computation of normals option. Not sure it's the best way, but at least it raises the idea in the event you come up with something more suitable.

[codecov-io]

Codecov Report

Merging #107 into master will increase coverage by 0.06%.
The diff coverage is 58.33%.

@@            Coverage Diff             @@
##           master     #107      +/-   ##
==========================================
+ Coverage   63.29%   63.36%   +0.06%     
==========================================
  Files         120      120              
  Lines        5882     5882              
==========================================
+ Hits         3723     3727       +4     
+ Misses       2159     2155       -4

Impacted Files	Coverage Δ
src/collision/TriangleVertexArray.cpp	75.37% <58.33%> (-0.79%)	⬇️
src/collision/MiddlePhaseTriangleCallback.h	0% <0%> (-100%)	⬇️
src/collision/CollisionDetection.h	85.71% <0%> (-14.29%)	⬇️
src/collision/HalfEdgeStructure.h	95.23% <0%> (-4.77%)	⬇️
src/collision/narrowphase/GJK/VoronoiSimplex.h	100% <0%> (ø)	⬆️
src/collision/ProxyShape.h	100% <0%> (ø)	⬆️
src/mathematics/Transform.h	100% <0%> (ø)	⬆️
src/collision/RaycastInfo.h	100% <0%> (ø)	⬆️
src/mathematics/Quaternion.h	95.71% <0%> (+0.06%)	⬆️
src/mathematics/Vector3.h	95.38% <0%> (+3.32%)	⬆️
... and 4 more

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Codecov Report

Attention: Patch coverage is 58.33333% with 5 lines in your changes missing coverage. Please review.

Project coverage is 63.36%. Comparing base (f9fa2a2) to head (a0b70fc).
Report is 777 commits behind head on master.

Files with missing lines	Patch %	Lines
src/collision/TriangleVertexArray.cpp	58.33%	5 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #107      +/-   ##
==========================================
+ Coverage   63.29%   63.36%   +0.06%     
==========================================
  Files         120      120              
  Lines        5882     5882              
==========================================
+ Hits         3723     3727       +4     
+ Misses       2159     2155       -4     

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