Meshoptimizer Versions Save

This release contains a number of fixes and improvements for vertex codec, substantially improves performance of several algorithms in Debug builds and introduces support for decompressing vertex/index data from JavaScript.

New algorithms:

• Introduce an experimental algorithm, meshopt_generateVertexRemapMulti, that generates the same remap table as meshopt_generateVertexRemap for indexing a mesh, but supports vertex data stored as multiple independent streams (deinterleaved)
• Introduce an experimental algorithm, meshopt_generateShadowIndexBufferMulti, that can generate a second index buffer that shares the vertex data with the original index buffer, but supports vertex data stored as multiple independent streams (deinterleaved)

Improvements:

• Optimize NEON code in meshopt_decodeVertexBuffer, making it 1-2% faster
• Improve compatibility of SIMD code in meshopt_decodeVertexBuffer, fixing compilation issues on ARM64, MSVC ARM, and clang for Windows
• Fix a bug in meshopt_encodeVertexBuffer that resulted in incorrectly encoded data on platforms where char is unsigned (this mostly affected ARM hosts such as Android)
• Substantially improve performance of multiple algorithms in Debug:
  • meshopt_analyzeVertexCache is 6x faster
  • meshopt_optimizeVertexCache is 4.7x faster
  • meshopt_analyzeOverdraw is 3.9x faster
  • meshopt_optimizeOverdraw is 1.4x faster
  • meshopt_simplify is 1.3x faster

JavaScript support:

• Introduce js/decoder.js that contains a WebAssembly version of vertex and index decoders with a JavaScript-friendly interface. The decoders run at 200-400 MB/s on modern desktop CPUs.
• Introduce tools/OptMeshLoader.js that contains an example mesh loader for THREE.js that uses vertex/index codecs for compression and quantizes vertex data for efficient storage; the meshes for this loader can be produced by tools/meshencoder.cpp using .OBJ files as an input.

This release substantially improves mesh simplification and introduces experimental algorithms for advanced GPU mesh rendering (cone culling, meshlet construction). The library can also now be used from Rust via https://crates.io/crates/meshopt.

Interface changes:

• meshopt_simplify has an extra argument, target_error, that can be used to limit the geometric error introduced by the simplifier

New algorithms:

• Introduce an experimental algorithm, meshopt_buildMeshlets, that can create meshlet data from index buffer that can be used to efficiently drive the mesh shading pipeline in NVidia RTX GPUs
• Introduce experimental algorithms, meshopt_computeClusterBounds and meshopt_computeMeshletBounds, that can compute bounding sphere and bounding normal cone for use in GPU cluster culling.
• Introduce an experimental algorithm, meshopt_generateShadowIndexBuffer, that can generate a second index buffer that shares the vertex data with the original index buffer, but is more efficient when a subset of vertex attributes is needed.

Improvements:

• Significantly rework meshopt_simplify to improve simplification quality, including error metric improvements, attribute-guided collapse that preserves UV seam structure better, and other tweaks
• Significantly rework and optimize meshopt_simplify, making it ~4x faster
• Optimize meshopt_generateVertexRemap, making it 1.25x faster
• Optimize meshopt_decodeVertexBuffer for platforms without SIMD support, making it 1.1x faster
• Fix undefined behavior (left shift of negative integer) in meshopt_encodeVertexBuffer

This release introduces vertex buffer encoder and a stable version of index buffer encoder.

New algorithms:

• Introduce vertex encoder that compresses vertex buffers; it can be invoked using meshopt_encodeVertexBuffer and meshopt_decodeVertexBuffer. The algorithm typically provides 1.5-2x compression ratio for quantized vertex data, and the resulting data can be compressed further by a general purpose compressor like zstd. Decoding is highly optimized using SSSE3/NEON and runs at 2 GB/s on a modern desktop CPU.
• Introduce a stable index encoder that compresses index buffers; it can be invoked using meshopt_encodeIndexBuffer and meshopt_decodeIndexBuffer. The algorithm typically encodes index buffers using ~3-4 bits per index, and the resulting data can be compressed further by a general purpose compressor like zstd, yielding ~2-3 bits per index for most meshes. Decoding is highly optimized and runs at 2 GB/s on a modern desktop CPU for 32-bit indices (1 GB/s for 16-bit indices).
• Introduce a new algorithm to optimize for vertex fetch, meshopt_optimizeVertexFetchRemap; it generates a remap table that can be used with meshopt_remapVertexBuffer/meshopt_remapIndexBuffer and helps optimizing meshes with several vertex streams.

Improvements:

• Optimize cluster sorting in meshopt_optimizeOverdraw, making the function 10% faster
• Optimize index decoder, making it 15% faster for 32-bit indices and 40% faster for 16-bit indices
• Fix meshopt_analyzeVertexCache and meshopt_analyzeVertexFetch results for sparse vertex buffers (with unused vertices)
• Support in-place optimization in meshopt_remapVertexBuffer
• Improve CMake build files to make the library easier to integrate

This release has large interface changes and introduces several new algorithms and tweaks to existing algorithms.

Interface:

• All C++ function wrappers have been moved out of meshopt namespace and gained meshopt_ prefix to simplify documentation & interface
• All structs used by the interface have been renamed and now also have meshopt_ prefix to avoid name conflicts
• meshopt_quantizeX functions now use function arguments instead of template parameters for better compatibility
• cache_size argument has been removed from meshopt_optimizeVertexCache and meshopt_optimizeOverdraw; to perform optimization for a FIFO cache of a fixed size, use meshopt_optimizeVertexCacheFifo

New algorithms:

• Introduce an algorithm that compresses index buffers; it can be invoked using meshopt_encodeIndexBuffer and meshopt_decodeIndexBuffer. The algorithm typically encodes index buffers using ~3-4 bits per index, and the resulting data can be compressed further by a general purpose compressor like zstd, yielding ~2-3 bits per index for most meshes.
• Introduce an algorithm that can convert an index buffer to a triangle strip that is still reasonably cache efficient; indexed triangle strips are faster to render on some hardware and can reduce the index buffer size. The algorithm can be invoked using meshopt_stripify and typically produces buffers with around 60-65% indices compared to triangle lists, and a 5-10% ACMR penalty on GPUs with small caches.
• Introduce a new quantization function, meshopt_quantizeFloat, that can reduce the precision of a floating-point number while keeping the floating-point representation. This can be useful to generate vertex data that can be compressed more effectively using a general purpose compression algorithm.

Improvements:

• Overdraw analyzer (meshopt_analyzeOverdraw) now uses a pixel center fill convention to match hardware rendering more closely.
• Vertex cache analyzer (meshopt_analyzeVertexCache) now models cache that matches real hardware a bit more closely, and requires additional parameters to configure (namely, primitive group size and warp/wavefront size).
• Vertex cache optimizer (meshopt_optimizeVertexCache) has been tuned to generate better output that performs well on real hardware, especially given meshes that have topology similar to that of a uniform grid as an input.
• Various algorithms have been optimized for performance and memory consumption.

This release has significant interface changes and introduces several new algorithms and tweaks to existing algorithms.

Interface:

• The library now has a C89 interface; meshoptimizer.hpp has been renamed to meshoptimizer.h accordingly. Templated functions are still available in namespace meshopt for C++.
• optimizeVertexFetch, optimizeOverdraw and analyzeOverdraw parameter order has changed - make sure to revise existing calls to these functions.

New algorithms:

• Introduce alternative vertex cache optimizer based on Tom Forsyth's algorithm; it can be invoked by setting cache_size parameter of optimizeVertexCache to 0. It generally takes ~3x longer to optimize meshes but usually produces more efficient output with the exception of regular grids.
• Introduce mesh simplification algorithm based on edge collapses, see meshopt::simplify. This is an early version of the algorithm - expect to see performance and quality improvements in future versions.

Fixes:

• remapVertexBuffer now correctly handles indexed vertex buffers where some vertices are not referenced
• optimizeOverdraw now correctly handles index buffers with degenerate triangles
• optimizeOverdraw is able to preserve the vertex cache efficiency much better

This is the first release of meshoptimizer library. Features:

• Algorithms to index or reindex meshes and optimize them for vertex cache, vertex fetch and overdraw
• Quantization helper functions to convert vertex attributes to GPU-friendly formats
• Algorithms that analyze efficiency of given meshes for vertex cache/fetch/overdraw
• C++ interface with support for 16-bit/32-bit indices

All algorithms have been optimized for both runtime performance (it's actually practical to run them at load time!) and efficiency of the resulting meshes.