![]() This constitutes back-face culling, computing gradients, and rasterization. The SetupRoutine performs primitive setup. ![]() Note that the vertex routine also performs vertex attribute reading, vertex caching, viewport transform, and clip flag calculation all in the same function. The fixed-function T&L pipeline is implemented by VertexPipeline, while programmable vertex processing with a shader is implemented by VertexProgram. The VertexRoutine produces a function for processing a batch of vertices. They also keep a cache of already generated routines, so that when a combination of states is encountered again it will reuse the routine that performs the desired processing. Each “processor” produces a corresponding Reactor routine, and manages the relevant graphics state. The Renderer layer is implemented in three main parts: the VertexProcessor, SetupProcessor, and PixelProcessor. More details on Reactor can be found in Reactor.md. We refer to the functions generated by Reactor code as Routines. Note that only one operation ends up in the generated code. For example to produce the code for an addition or a subtraction, one could write x = addOrSub ? x + y : x - y. While making Reactor's syntax so similar to the C++ in which it is written might cause some confusion at first, it provides a powerful abstraction for code specialization. Likewise If(), Else, and For(,) implement their C counterparts. Note that Reactor types have the same names as C types, but starting with a capital letter. Using C++ operator overloading, Reactor simplifies this to Float y = 1 - x. This is very verbose and becomes hard to read for longer expressions. To generate code for an expression such as float y = 1 - x directly with LLVM, we'd need code like Value *valueY = BinaryOperator::CreateSub(ConstantInt::get(Type::getInt32Ty(Context), 1), valueX, "y", basicBlock). Reactor records its operations in an in-memory intermediate form which can be materialized by the JIT into a function which can be called directly. The JIT layer is a run-time compiler, such as LLVM's JIT, or Subzero. Its syntax closely resembles C and shading languages, to make the code generation easily readable. It allows to specialize the processing routines for the state and shaders used by each draw call. ![]() Reactor is an embedded language for C++ to dynamically generate code in a WYSIWYG fashion. It defines the data structures used and how the processing is performed. The Renderer layer generates specialized processing routines for draw calls and coordinates the execution of rendering tasks. ![]() It is responsible for managing API-level resources and rendering state, as well as compiling high-level shaders to bytecode form. The API layer is an implementation of a graphics API, such as OpenGL (ES) or Direct3D, on top of the Renderer interface. Structurally there are four major layers: Parallel processing means both utilizing the CPU's multiple cores and processing multiple elements accoss the width of the SIMD vector units. Generating code at run-time allows to eliminate code branches and optimizes register usage, specializing the processing routines for exactly the operations required by each draw call. To achieve exceptional performance, SwiftShader is built around two major optimizations that affect its architecture: dynamic code generation, and parallel processing. It can run entirely in user space, or as a driver (for Android), and output to either a frame buffer, a window, or an offscreen buffer. Applications already using these APIs thus don't require any changes to use SwiftShader. SwiftShader provides shared libraries (DLLs) which implement standardized graphics APIs. It eliminates the dependency on graphics hardware capabilities. ![]() SwiftShader provides high-performance graphics rendering on the CPU. :warning: Out of date SwiftShader Documentation ![]()
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