multi layere alpha blending
https://software.intel.com/en-us/articles/multi-layer-alpha-blending
这里是intel的paper
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metal有代码实现
https://developer.apple.com/sample-code/metal/Order-Independent-Transparency-with-Imageblocks.zip
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https://www.cnblogs.com/minggoddess/p/10826895.html
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https://matthewwellings.com/blog/depth-peeling-order-independent-transparency-in-vulkan/
depth peeling
github
https://github.com/openforeveryone/VulkanDepthPeel
http://jcgt.org/published/0002/02/09/
abuffer
======================
http://on-demand.gputechconf.com/gtc/2014/presentations/S4385-order-independent-transparency-opengl.pdf