193 lines
6.4 KiB
Markdown
193 lines
6.4 KiB
Markdown
# tenvex
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A header-only C++20 SIMD math library for high-performance 4D vector arithmetic.
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tenvex uses **expression templates** — a C++ template metaprogramming technique that enables lazy, zero-overhead evaluation of chained vector operations. Complex expressions like `norm(a + b * 2.0f) * dot(b, c) + c * 3.0f` compile down to a single fused sequence of SSE/AVX intrinsics with no intermediate temporaries.
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## Features
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- Header-only — just include `tenvex.h`
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- Expression template engine with zero-cost abstractions
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- All arithmetic backed by SSE/AVX intrinsics (`__m128`)
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- C++20 concepts enforce type safety at compile time
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- Smart storage policy: small trivial types stored by value, others by `const&`
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- Supported operations: `+`, `-`, `*` (scalar), `dot`, `cross`, `norm`, `magnitude`
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## Requirements
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- C++20 compiler (MSVC, GCC, Clang)
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- x64 CPU with SSE2 support
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- [Premake5](https://premake.github.io/) (binaries included for Windows, Linux, macOS)
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## Getting Started
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tenvex is header-only. Copy `src/tenvex/` into your project and include the single public header:
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```cpp
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#include "tenvex.h"
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```
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### Basic Usage
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```cpp
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#include "tenvex.h"
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using namespace tnvx;
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vec4 a = { 1.0f, 2.0f, 3.0f, 0.0f };
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vec4 b = { 4.0f, 5.0f, 6.0f, 0.0f };
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vec4 c = { 1.0f, 0.0f, 1.0f, 0.0f };
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// Basic arithmetic
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vec4 sum = a + b;
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vec4 diff = a - b;
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vec4 scaled = a * 2.0f;
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vec4 scaled2 = 3.0f * b;
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// Vector operations
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float d = dot(a, b);
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vec4 cr = cross(a, b);
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vec4 n = norm(a);
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float mag = magnitude(a);
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// Compound expressions — evaluated lazily, no temporaries
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vec4 result = norm(a + b * 2.0f) * dot(b, c) + c * 3.0f;
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```
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### `vec4` Member Functions
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```cpp
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vec4 v = { 1.0f, 2.0f, 3.0f, 4.0f };
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float x = v.x(); // component accessors
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float y = v.y();
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float z = v.z();
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float w = v.w();
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auto arr = v.data(); // std::array<float, 4>
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float mag = v.magnitude(); // vector length
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vec4 n = v.norm(); // unit vector
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```
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### Comparison
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```cpp
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vec4 a = { 1.0f, 2.0f, 3.0f, 4.0f };
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vec4 b = { 1.0f, 2.0f, 3.0f, 4.0f };
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bool exact = (a == b); // exact equality
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bool approx = approx_eq(a, b); // epsilon = 1e-3 (default)
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bool approx = approx_eq(a, b, 1e-6f); // custom epsilon
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```
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## Architecture
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### Expression Templates
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Every operation returns a lazy expression node rather than evaluating immediately. Nodes inherit from `Expr<Derived>` via CRTP and expose a single `__m128 eval() const` method. Evaluation only happens when the result is assigned to a `vec4`.
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```
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vec4 result = norm(a + b * 2.0f) * dot(b, c) + c * 3.0f;
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// └─ Mul<Norm<Add<vec4, Mul<vec4, Scalar>>>, Mul<Dot<vec4,vec4>, Mul<Scalar,...>>>
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// ↑ entire tree collapsed to ~5 SSE instructions at assignment
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```
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### C++20 Concepts
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| Concept | Meaning |
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|----------------------|----------------------------------------------|
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| `expression<T>` | Any `Expr<T>` subtype with `__m128 eval()` |
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| `vector_expression<T>` | An `expression` that is not a `Scalar` |
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### Storage Policy
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To avoid dangling references to temporary expression nodes, storage is chosen automatically:
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```cpp
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// trivially copyable & destructible & sizeof <= 16 → stored by value
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// otherwise → stored as const T&
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template<typename T>
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using tnvx_type_storage = std::conditional_t<tnvx_store_by_value<T>, T, const T&>;
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```
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### Operation Nodes
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| Node | Intrinsic(s) | Notes |
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|-----------------|-------------------------------------|------------------------------------|
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| `Add<L,R>` | `_mm_add_ps` | |
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| `Sub<L,R>` | `_mm_sub_ps` | |
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| `Mul<E,Scalar>` | `_mm_mul_ps` | Scalar multiplication only |
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| `Dot<L,R>` | `_mm_mul_ps` + horizontal shuffle | Result broadcast to all 4 lanes |
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| `Cross<L,R>` | `_mm_mul_ps` + `_mm_sub_ps` + shuffles | 3-component; w = 0 |
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| `Norm<E>` | `_mm_div_ps` + `_mm_sqrt_ps` | Divide by magnitude |
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| `Magnitude<E>` | `_mm_sqrt_ss` | Scalar result |
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| `Scalar` | `_mm_set1_ps` | Broadcasts float to all 4 lanes |
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## Building
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The build system uses [Premake5](https://premake.github.io/). Premake5 binaries are included in `premake/bin/` for all platforms.
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### Windows (Visual Studio 2022)
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```bat
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scripts\config-vs2022.bat
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```
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Then open the generated solution in `build/` and build the `tenvex_tests` project.
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### Other Platforms
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Run the appropriate Premake5 binary manually:
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```sh
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# Linux
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./premake/bin/linux/premake5 gmake2
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# macOS
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./premake/bin/macos/premake5 gmake2
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```
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Then:
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```sh
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make config=debug
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```
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Build output is written to `bin/<system>/x64/<debug|release>/output/`.
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## Running Tests
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The test suite uses Google Test (vendored in `thirdparty/gtest/`) and covers 18 cases:
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| Category | Tests |
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|--------------------|-----------------------------------------------------------------------|
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| Basic operations | `add`, `sub`, `mult_a`, `mult_b`, `dot`, `cross`, `norm_a/b`, `magnitude_a/b` |
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| Compound expressions | `expression_a`, `expression_b`, `expression_c` |
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| Math properties | `cross_anticommutative`, `dot_commutative`, `norm_magnitude`, `dot_perpendicular`, `cross_parallel` |
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Build and run `tenvex_tests` from the generated project or makefile.
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## Project Structure
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```
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tenvex/
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├── src/
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│ ├── tenvex/ # Library headers (header-only)
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│ │ ├── tenvex.h # Single public include
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│ │ ├── vec4.h / vec4_impl.hpp
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│ │ └── internal/ # Expression nodes and infrastructure
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│ └── tests/
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│ └── vec4_tests.cpp # Google Test suite
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├── thirdparty/
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│ └── gtest/ # Vendored Google Test
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├── premake/
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│ └── bin/ # Premake5 binaries (Windows, Linux, macOS)
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├── scripts/
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│ └── config-vs2022.bat # VS2022 project generation
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└── premake5.lua # Build configuration
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```
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## License
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BSD 3-Clause License. Copyright (c) 2026 Artem Zyktin. See [LICENSE.txt](LICENSE.txt).
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