John Calsbeek Nexuapex

Use cases

Textures/Matrices for direct use (data!)

Moments In Graphics (void-and-cluster)
- 2D
- 3D and 4D
Bart Wronski Implementation of Solid Angle algorithm

One thing that surprises newer programmers is that the older 8-bit microcomputers from the 70s and 80s were designed to run at the speed of random memory access to DRAM and ROM. The C64 was released in 1982 when I was born and its 6502 CPU ran at 1 MHz (give or take depending on NTSC vs PAL). It had a 2-stage pipelined design that was designed to overlap execution and instruction fetch for the current and next instruction. Cycle counting was simple to understand and master since it was based almost entirely on the number of memory accesses (1 cycle each), with a 1-cycle penalty for taken branches because of the pipelined instruction fetch for the next sequential instruction. So, the entire architecture was based on keeping the memory subsystem busy 100% of the time by issuing a read or write every cycle. One-byte instructions with no memory operands like INX still take the minimum 2 cycles per instruction and end up redundantly issuing the same memory request two cycles in a row.

Effective Modern CMake

Getting Started

For a brief user-level introduction to CMake, watch C++ Weekly, Episode 78, Intro to CMake by Jason Turner. LLVM’s CMake Primer provides a good high-level introduction to the CMake syntax. Go read it now.

After that, watch Mathieu Ropert’s CppCon 2017 talk Using Modern CMake Patterns to Enforce a Good Modular Design (slides). It provides a thorough explanation of what modern CMake is and why it is so much better than “old school” CMake. The modular design ideas in this talk are based on the book [Large-Scale C++ Software Design](https://www.amazon.de/Large-Scale-Soft

	enum { BMAX = 32, BCUT = BMAX / 2, BHEIGHT = 6 };

	typedef uint8_t BIndex;

	struct BNode {
	BIndex length;
	Key keys[BMAX];
	union {
	BNode *children[BMAX];
	Value values[BMAX];

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	Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
	mysterious cases where it helps?

	A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
	I think it's useful to know what compiler writers are accomplishing by this.

	TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
	major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
	fairly common cases. The signed overflow UB exploitation is an attempt to work around this.

	// The following code is licensed under the MIT license: https://gist.github.com/TheRealMJP/bc503b0b87b643d3505d41eab8b332ae

	// Samples a texture with Catmull-Rom filtering, using 9 texture fetches instead of 16.
	// See http://vec3.ca/bicubic-filtering-in-fewer-taps/ for more details
	float4 SampleTextureCatmullRom(in Texture2D<float4> tex, in SamplerState linearSampler, in float2 uv, in float2 texSize)
	{
	// We're going to sample a a 4x4 grid of texels surrounding the target UV coordinate. We'll do this by rounding
	// down the sample location to get the exact center of our "starting" texel. The starting texel will be at
	// location [1, 1] in the grid, where [0, 0] is the top left corner.
	float2 samplePos = uv * texSize;

	#include <emmintrin.h>
	#include <tmmintrin.h> // for PSHUFB; this isn't strictly necessary (see comments in reverse_s16)

	typedef int16_t S16;
	typedef __m128i Vec;

	static inline Vec load8_s16(const S16 x) { return _mm_loadu_si128((const __m128i ) x); }
	static inline void store8_s16(S16 x, Vec v) { _mm_storeu_si128((__m128i ) x, v); }

	static inline void sort_two(Vec &a, Vec &b) { Vec t = a; a = _mm_min_epi16(a, b); b = _mm_max_epi16(b, t); }

	// TransientFuction: A light-weight alternative to std::function [C++11]
	// Pass any callback - including capturing lambdas - cheaply and quickly as a
	// function argument
	//
	// Based on:
	// https://deplinenoise.wordpress.com/2014/02/23/using-c11-capturing-lambdas-w-vanilla-c-api-functions/
	//
	// - No instantiation of called function at each call site
	// - Simple to use - use TransientFunction<> as the function argument
	// - Low cost: cheap setup, one indirect function call to invoke


	//
	// TinyCRT, revamp and TinyWin support by Don Williamson, 2011
	// Based on http://www.codeproject.com/KB/library/tlibc.aspx and LIBCTINY by Matt Pietrek
	//

	#pragma once


	#ifdef USE_DEFAULT_CRT