Jonathan Dupuy jdupuy

jdupuy / Inverse.cpp

Last active March 12, 2020 10:01

C++ code to compute the inverse of a linearly-interpolated 1D table with values in [0, 1] x [0, 1] (note: the table size must be a power of two)

	#include <cstdio>
	#include <cstdlib>
	#include <cmath>
	#include <vector>

	// inverting piecewise linear functions
	float InverseLinear(float yStart, float yEnd, float y)
	{
	return (y - yStart) / (yEnd - yStart);
	}

jdupuy / BitonicSort.c

Created June 1, 2022 09:28

CPU Bitonic Sort

	// sorts an array in ascending order (arraySize muste be a power of two)
	void BitonicSort(uint32_t *array, uint32_t arraySize)
	{
	for (uint32_t d2 = 1u; d2 < arraySize; d2*= 2u) {
	for (uint32_t d1 = d2; d1 >= 1u; d1/= 2u) {
	const uint32_t mask = (0xFFFFFFFEu * d1);

	#pragma omp parallel for
	for (uint32_t i = 0; i < (arraySize / 2); ++i) {
	const uint32_t i1 = ((i << 1) & mask) \| (i & ~(mask >> 1));

jdupuy / SampleVndf_GGX.cpp

Last active September 24, 2024 15:22

Sampling Visible GGX Normals with Spherical Caps

	// Helper function: sample the visible hemisphere from a spherical cap
	vec3 SampleVndf_Hemisphere(vec2 u, vec3 wi)
	{
	// sample a spherical cap in (-wi.z, 1]
	float phi = 2.0f * M_PI * u.x;
	float z = fma((1.0f - u.y), (1.0f + wi.z), -wi.z);
	float sinTheta = sqrt(clamp(1.0f - z * z, 0.0f, 1.0f));
	float x = sinTheta * cos(phi);
	float y = sinTheta * sin(phi);
	vec3 c = vec3(x, y, z);

jdupuy / BitReverse.c

Last active April 24, 2024 12:01

Reversing bits of a word