Reference Renderer Design Notes
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Requirements:
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- must support arbitrary VA arrays
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- must support primitive setup reference
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- must support lines, points
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- must support instancing
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- must support vertex shading -> custom position transformations
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- flat, noperspective shading
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- multiple render targets
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- faster shading? move packet loop inside shader
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(helper class can make shader implementation easier)
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- can be extended for tessellation and geometry shading
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Integrate with:
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- sglr
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- random shader generator
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Uniforms:
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- shader objects can contain parameters, renderer doesn't care about them
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- can contain simple data or references to resources (textures for example)
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Pipeline:
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Vertex cache:
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- based on indices setup transformed vertex buffer
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- in:
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+ index list
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+ VS generic output count
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- out:
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+ VS execution queue
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+ index remap information?
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- trivial implementation:
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+ run VS for all vertices at once
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VertexShader:
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- provides position & point size
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- transforms other vertices
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- in:
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+ VertexAttrib array
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+ packet list:
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+ VertexID, InstanceID (pack into some accessor?)
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+ uniform ptr
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- out:
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+ position
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+ point size
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+ array of generic transformed attributes (float/int/uint)
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Tessellation:
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- \todo [pyry] Define
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- replaces primitive assembly?
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Primitive assembly:
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- sets up primitives
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- gl3: triangles, points, lines (adjecency?)
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- in:
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+ full primitive type
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+ index list
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+ position & point size from VS
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- out:
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+ primitive list for rasterization / geometry shading
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+ positions
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+ provoking vertex for flatshading
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GeometryShader:
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- in:
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+ primitive list
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- out:
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+ changed primitive list
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Coordinate transform:
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- in:
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+ primitive list
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- out:
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+ coordinates after viewport transform
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+ z-clipping bits
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Rasterizer:
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- pretty much as it is currently
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FragmentShader:
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- in:
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+ packet list:
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+ base coordinates
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+ barycentrics, both perspective and non-perspective
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+ generic attribute accessor (2 or 3 vertices)
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+ provoking vertex index
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+ uniform ptr
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- out:
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+ shaded packet list:
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+ colors per render target
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+ modified live mask - for discard
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- utils:
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+ compute derivatives from data in SoA form
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+ compute lod for texturing
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