niagra notes.md

Setup (not per frame)

...

Load mesh Process for a mesh:

1- get verts/indices (duh) 2- You need buffer(s) Buffer needs VKBuffer and VkDeviceMemory 3- To set up a buffer, you need CreateInfo you need to call VkBuffer You need to figure out memory requirements You need to allocate memory You need to Bind memory If you're binding multiple buffers to one set of memory, you need to supply offset You need to Map Memory for a cpu visible pointer to the memory

Freeing requires VKFreeMemory
    Memory is "persistently mapped", dont have to unmap
    Need to VKDestroy Buffer

Arseny memcpys mesh data directly into that buffer. VK tutorials do something else right?

Adding mesh data to pipeline Arseny clals this the "old" ffp way WHILE CREATING PIPELIEN AFter stages, Before statecreateinfo Configure VkPipelineVertexInputStateCreateInfo Which requires VkPipelineVertexInputBindingDescription and VkPipelineVertexInputAttrributeDescription Binding description contains some info about the formatting of data, unclear to me

Modern way: Bindless?

    Arseny uses a NON-AMD extension called "VK_KHR_PUSH_DESCRIPTOR_EXTENSION_NAME" 
    "Use push descriptors to just send data to the shader without managing descriptor sets ourselves"

    Arseny ran into an issue where he needed vkphysicaldevicefeatures.vertexpipelinestoresandatomics

    Bindings for the pipeline:
    While creating grapics pipeline (vkpipelinelayoutcreateinfo), we need a descriptorsetlayout and a descriptorsetlayoutcreateinfo to pass in. The descriptorsetlayout needs flags to support push, and an array of descriptorsetlayoutbinding, one for eac thing we can bind(???). 
    A descriptorsetlayoutbinding needs descriptor type and offset, stage flags (VK_SHADER_STAGE_) and descriptortype -- VK_DESCRIPTION_TYPE_STORAGE_BUFFER.
    The descriptorsetlayoutcreateinfo is constructed like this:
        VkDescriptorSetLayoutInfo setCreateInfo = {VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO}
        setCreateInfo.flags = VK_DESCRIPTOR_SET_PUSH_DESCRKIPTOR_BIT_KHR 
        setinfo.binding count = number of bindings
        setcreateinfo.pbindings = setlayoutbinding 

    Can destroy set layout right aftercalling create pipeline  

Per frame (?)

Drawing mesh Old Way After binding pipeline, (naturally) before draw VKCmdBindVertexBuffers VkCmdBindIndexBuffer VkCMdDrawIndexed

Modern way: Bindless?
    Remove bindvertexbuffer 
        //This is our extension I guess
    Create vkDescriptorBufferInfo 
        takes buffer (this is our vertex buffer we created with the mesh)
        offset and range (size of vbuffer)
    Create vkWriteDescriptorSet
        Takes type, binding (offset?), count, descriptortype, and bfuferinfo
    Call vkCmdPushDescriptorSetKHR 
        Takes bind poijnt (graphics), layout, count/etc info, and descriptorset

This draws mesh.


Arseny does uint_8_t normals and takes (normal / 127.0 - 1) for more compact/less precise normals
on GLSL this requires extensions: GL_EXT_shader_16bit_storage, GL_EXT_shader_8bit_storage, GL_KHX_shader_explicit_arithmetic_types
And some vulkan extensions: VK_KHR_16BIT_STORAGE_EXTENSION_NAME, VK_KHR_8BIT_STORAGE_EXTENSION_NAME 
    THis requires a physicaldevice feature which isn't included in features -- he does a pattern with "features2". Look at code if needed.

NOTE: niagra mesh shader extension is the old nvidia specific one -- modern is this: https://www.khronos.org/blog/mesh-shading-for-vulkan https://github.com/nvpro-samples/gl_vk_meshlet_cadscene Mesh Shaders