To reduce complexity and repetitive copy-pasted spaghetti code,
the design approach here was to implement triangle fan conversion on
MVKCmdDrawIndexedIndirect, as the most general of the draw commands,
and then populate and invoke a synthetic MVKCmdDrawIndexedIndirect
command from the other draw commands.
- Rename pipeline factory shader cmdDrawIndexedIndirectMultiviewConvertBuffers()
to cmdDrawIndexedIndirectConvertBuffers, and in addition to original support
for modifying indirect content to support multiview, add support for
converting triangle fan indirect content and indexes to triangle list.
- Modify MVKCmdDrawIndexedIndirect to track need to convert triangle fans
to triangle list, and invoke kernel function when needed.
- Modify MVKCmdDraw, MVKCmdDrawIndexed, and MVKCmdDrawIndirect to populate
and invoke a synthetic MVKCmdDrawIndexedIndirect command to convert triangle
fans to triangle lists.
- Add pipeline factory shader cmdDrawIndirectPopulateIndexes() to convert
non-indexed indirect content to indexed indirect content.
- MVKCmdDrawIndexedIndirect add support for zero divisor vertex buffers
potentially coming from MVKCmdDraw and MVKCmdDrawIndexed.
- Rename pipeline factory shader cmdDrawIndexedIndirectConvertBuffers()
to cmdDrawIndexedIndirectTessConvertBuffers() so it will be invoked from
MVKCommandEncodingPool::getCmdDrawIndirectTessConvertBuffersMTLComputePipelineState()
(unrelated).