[doranteseduardo]

Summary

A crash on iOS when the world mesh's debug drawing is on: VROPolyline::buildElement built its index list as a variable-length array on the stack.

Cause

• VROPencil::render (the world mesh's debugDrawEnabled) turns every mesh edge into one polyline each frame. buildElement then declared int indices[numCorners] on the stack.
• With 3.1.0's accumulated world mesh, a room reaches hundreds of thousands of corners, so the array overflowed the iOS main thread's stack.
• The crash: EXC_BAD_ACCESS, "Thread stack size exceeded", in ___chkstk_darwin ← VROPolyline::buildElement ← VROPencil::render, on an iPhone 16 Pro running the showcase world mesh scene.

Fix

• VROPolyline::buildElement and VROPolygon::buildElement, which has the same unbounded stack array, build their indices in a std::vector.
• VROData copies the bytes by default, so the vector can go once the element is built.

Notes

• Debug drawing a large accumulated mesh is still expensive, since every edge is redrawn each frame. It is a debugging aid; the showcase scene now starts with it off.
• CHANGELOG (3.1.0) updated.

Testing

• Built with scripts/build.sh (Android AAR, iOS device and simulator). The rebuilt binaries ship in viro's companion PR.