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zeux /
Last active Jan 27, 2020
Writing down various options to extend meshoptimizer encoding API with format versioning


meshoptimizer currently ships with index and vertex codecs with the API along these lines:

size_t encode(destination, destination_capacity, source, source_size)
void decode(destination, destination_size, source, source_size)

The next version of meshoptimizer needs to make backwards incompatible changes to the encoding format to allow for better compression.


State of Roblox graphics API across all platforms, with percentage deltas since EOY 2019. Updated February 13 2020.


API Share
Direct3D 11+ 86%
Direct3D 10.1 8%
Direct3D 10.0 5%
Direct3D 9 1%
zeux / types.lua
Created Jan 18, 2020
Luau dumptypes output as of 1/17/2020
View types.lua
This file has been truncated, but you can view the full file.
type AdvancedDragger={
zeux / nbody.s
Last active Jan 2, 2020
luaujit: nbody.lua when compiled using experimental Luau JIT engine. All assembly snippets only show inner loop body. Variants: scalar - using type info, records and basic block compiler to generate much more efficient inner loop; vector - scalar but with scalars replaced with first-class 3-component vector
View nbody.s
# table type guard (memory safety)
cmp dword ptr [rdi + 12], 6
jne 1072 <.text+0x5ea>
# load array index and convert to integer (+ exactness check)
movsd xmm0, qword ptr [rdi + 256]
cvttsd2si eax, xmm0
cvtsi2sd xmm1, eax
ucomisd xmm1, xmm0
jne 1046 <.text+0x5ea>
# indices are 1-based; could remove this one with runtime changes
zeux / islandize-reuv.cpp
Last active Jun 25, 2019
Isolate UV islands and move each island to 0..1 range if possible; this reduces the total UV range of the mesh.
View islandize-reuv.cpp
unsigned int follow(std::vector<unsigned int>& ids, unsigned int v)
unsigned int nv = v;
while (ids[nv] != nv)
nv = ids[nv];
return ids[v] = nv;
size_t islandize(const std::vector<unsigned int>& indices, std::vector<unsigned int>& islands)
zeux /
Last active Jun 13, 2019
Notes on supporting half-precision computation in SPIRV based shader pipelines

The following assumes that HLSL source is used as an input for shader compilation, glslang is used to compile it to SPIRV, and then SPIRV-Cross is optionally used to compile the result to MSL/GLSL.

First, make sure you use min16floatN type instead of halfN type. This is necessary because glslang treats halfN type (with default compilation options) as floatN because unfortunately that's what DX10 does as well.

#define half min16float
#define half2 min16float2
#define half3 min16float3
View decomposetrs.cpp
void decomposeMatrix(const float* matrix, float translation[3], float rotation[4], float scale[3])
translation[0] = matrix[12];
translation[1] = matrix[13];
translation[2] = matrix[14];
// 0 1 2
// 4 5 6
// 8 9 10
float det =
zeux / luau_features.pdf
Last active Feb 25, 2020
Frequently asked questions about the Lua VM work we (Roblox) are doing.
View luau_features.pdf
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zeux / murmur.h
Last active Feb 28, 2019
MurMurHash finalizers as 32-bit integer/pointer hashers
View murmur.h
uint32_t murmur2(uint32_t h)
h ^= h >> 13;
h *= 0x5bd1e995;
h ^= h >> 15;
return h;
uint32_t murmur3(uint32_t h)
zeux / simplifier.cpp
Created Feb 18, 2019
SIMD sloppy simplifier for "Flavors of SIMD" blog post
View simplifier.cpp
// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
#include "meshoptimizer.h"
#include <assert.h>
#include <float.h>
#include <math.h>
#include <string.h>
#ifndef TRACE
#define TRACE 0
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