Assets hot reloading

[voxelias]

• Add dirty flag to assets
• Add timestamp of last file modification
• Add a new thread to control last file modification timestamp and reschedule the import
• Set dirty flag, if the asset was updated
• Make sure buffers being updated and dirty flag is unset

[QuantumEntangledAndy]

I am thinking of maybe something like this. Separate the gpu and cpu representations. Assets represents the data on the cpu buffers that on gpu.

Both assets and buffers have a revision number. When an asset is changed the number is incremented.

Gpu objects have a function that is something like which is called as part of the render system.

fn load(&mut self, cpu: & CpuRepresentation) {
  // check if buffer revision == asset revision if not copy data from cpu to gpu
}

Function should return something like.

enum Update {
  Structure,
  Data,
  None
}

A Structure update indicated that the underlaying data structure like buffer size or texture dimensions was changed and that the render system should rebind.

A Data update indicates that new data was put into the buffer but that the structure was not changed. It can just re-queue the same gpu pipeline.

A None update means no change. Depending on the system it may not even want to re-queue the gpu pipeline.

By using revision rather than dirty we are more resistant to the case where there are multiple buffer that need updating off the same cpu data.