tree dc959250f5bcb9e13c541b693d5eec8fa5682925
parent e53e58263914ed641c03af2379dce3acb2cde308
author Bill Hollings <bill.hollings@brenwill.com> 1579616298 -0500
committer Bill Hollings <bill.hollings@brenwill.com> 1579616298 -0500

Support preallocated descriptor pooling via VkDescriptorPoolSize.

Add MVK_CONFIG_PREALLOCATE_DESCRIPTORS env var to enable descriptor preallocation
in pool. Add MVKDescriptor subclasses for all used VkDescriptorType values.
Support allocating MVKDescriptor subclasses via direct instantiation,
or referencing preallocated instances held in a fixed collection.
MVKDescriptor subclasses support resetting and reuse from preallocated collection.
MVKDescriptorPool optionally holds collections of preallocated descriptors,
one collection per VkDescriptorType value.
Support VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT to mark preallocated
descriptors as available when freed.