Perl_SDL: Hardware supports stencil buffers but it doesn't work in OpenGL

[ATC]

When using a 3D accelerator card which supports 32 bit Z/stencil buffers, OpenGL is only using 16 bits for Z (depth) buffering and stencils don't work at all.

glGet(GL_DEPTH_BITS) returns 16
glGet(GL_STENCIL_BITS) returns 0

Also, when trying to glEnable(GL_STENCIL_TEST), rendering becomes extremely slow.

[ATC]

Most OpenGL drivers require the depth of the Z and stencil buffers to be specified during initialization, otherwise the most common default values are  16 and 0 respectively.

In the case of Perl_SDL, use the options -depth and -stencil_size when calling SDL::App->new()