rygorous’s gists

rygorous / gist:6f96cc21292cc704f53ef77e5b4be519

Created May 22, 2025 02:25

Oodle Texture BC7RD "preserve extremes" constraint validation

	//===================================================================
	// constraint validation for preserve extremes mode

	// Cold part of are_endpoitns_permitted: the actual constraint validation
	static RADNOINLINE bool are_endpoints_permitted_cold(const BC7BlockState & st, const bc7rd_blockinfo& info)
	{
	const BC7Flags flags = info.flags;

	if (st.mode <= 3)
	{

rygorous / gist:52cc2a23a73813d645581046dced27fd

Created May 22, 2025 00:15

Oodle Texture "preserve extremes" rules

	{
	BC7Flags flags = in_flags;

	// Preserve extremes mode.
	//
	// This mode preserves values of 0 and 255 in the alpha channel exactly. In general,
	// we can do this in any one channel, but restricting this to alpha makes the interface
	// simpler, is consistent with what we do for BC3, and doesn't seem like a signfiicant
	// limitation for the user.
	//

rygorous / gist:94fd3c33afe4e650ec5bda386cbc16bb

Created May 8, 2025 01:16

	uint EvenBitMask = 0x55555555u;
	uint HighIndexBit = PackedIndices >> 1;

	float NumWeight1 = float(countbits(EvenBitMask & ~HighIndexBit & PackedIndices));
	float NumWeight2 = float(countbits(EvenBitMask & HighIndexBit & ~PackedIndices));
	float NumWeight3 = float(countbits(EvenBitMask & HighIndexBit & PackedIndices));

	// with NV LOP3: 1 shift, 3 LOP3, 3 pop count, 3 int->float = 10 insns total for 16 pixels
	// without: 1 shift, 2 NOT, 5 AND, 3 pop count, 3 int->float = 14 insns total for 16 pixels

rygorous / rr_dds.h

Created March 7, 2025 01:45

rr_dds loader/writer

	//===================================================
	// Oodle2 DDS Tool
	// (C) Copyright 1994-2022 Epic Games Tools LLC
	//===================================================

	#ifndef RR_DDS_INCLUDED
	#define RR_DDS_INCLUDED

	#include <stdint.h>
	#include <stddef.h>

rygorous / main.rs

Created March 2, 2025 04:42

Base64 fixed point test

	use bit_set::BitSet;
	use std::mem;

	// Vanilla RFC 4648
	const ALPHABET: &str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
	// URL-safe RFC 4648
	//const ALPHABET: &str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
	const COUNT: usize = 1usize << 24; // 3 bytes worth suffices for this test

	fn lookup(index: u32) -> u32 {

rygorous / bc7rd_chart_example.html

Created January 2, 2025 09:46

Example run with a BC7 RD plot diff

	<!DOCTYPE html>
	<html><head>
	<meta http-equiv="content-type" content="text/html; charset=UTF-8">
	<style>
	body { background: #fff; margin: 10px; font: 12pt Calibri,Arial,Helvetica,sans-serif; }
	h1 { font-size: 18pt; margin: .5em 0 .5em 0; }
	h2 { font-size: 16pt; margin: .5em 0 .5em 0; }
	canvas { margin: auto; }
	table { border-spacing: 0; }
	table.rdresult tbody tr:nth-child(even) { background: #eee; }

rygorous / rdchart_template_prefix.html

Created January 2, 2025 09:40

RD chart template for Oodle Texture eval

	<!DOCTYPE html>
	<html>
	<head>
	<style>
	body { background: #fff; margin: 10px; font: 12pt Calibri,Arial,Helvetica,sans-serif; }
	h1 { font-size: 18pt; margin: .5em 0 .5em 0; }
	h2 { font-size: 16pt; margin: .5em 0 .5em 0; }
	canvas { margin: auto; }
	table { border-spacing: 0; }
	table.rdresult tbody tr:nth-child(even) { background: #eee; }

rygorous / main.cpp

Created December 24, 2024 15:07

Direct UNORM/SNORM conversion test program

	#include <stdio.h>
	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>

	static uint32_t float_to_bits(float x)
	{
	uint32_t u;
	memcpy(&u, &x, sizeof(x));
	return u;

rygorous / gist:bdec6f2f3b193f6e0db54cc852b433c3

Created November 22, 2024 00:02

	// ep1 - ep0 >= 0: four-interpolated color mode
	// ep1 - ep0 < 0: six-interpolated-color mode
	//
	// we want to avoid ep0 = ep1 in general (because it gives us no useful
	// interpolated values). That means in four-interp mode we want ep1 - ep0 > 0,
	// and in six-interp mode we want ep1 - ep0 < 0. If they're identical or
	// have the wrong sign, we need to fix it!
	int ep_diff = ((ep1_int - ep0_int) ^ target_sign) - target_sign;
	if (ep_diff <= 0)
	{

rygorous / gist:991df2d8dae81ba1a844a2b0f99559ea

Last active November 15, 2024 06:58

	template <int t_nbits>
	static inline void quant_endpoint_with_pbit(U8 deq0, U8 deq1, int val)
	{
	const int expanded_nbits = t_nbits + 1;
	const U32 range = 1u << expanded_nbits;
	const U32 recip255 = 0x8081; // enough bits for our value range
	const int postscale = (0x10000 >> t_nbits) + (0x10000 >> (t_nbits*2 + 1));

	// The reconstruction here adds the pbit as the lowest bit and then reconstructs
	// it as a (nbits+1)-bit value to float, i.e. (quant*2 + pbit) / (range - 1).

Fabian 'ryg' Giesen rygorous