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diff --git a/Shaders/cloud/hg_sdf.cginc b/Shaders/cloud/hg_sdf.cginc new file mode 100644 index 0000000..b1de0b0 --- /dev/null +++ b/Shaders/cloud/hg_sdf.cginc @@ -0,0 +1,187 @@ +#ifndef __HG_SDF__ +#define __HG_SDF__ + +#include "pema99.cginc" + +//////////////////////////////////////////////////////////////// +// +// HG_SDF +// +// GLSL LIBRARY FOR BUILDING SIGNED DISTANCE BOUNDS +// +// version 2021-07-28 +// +// Check https://mercury.sexy/hg_sdf for updates +// and usage examples. Send feedback to spheretracing@mercury.sexy. +// +// Brought to you by MERCURY https://mercury.sexy/ +// +// +// +// Released dual-licensed under +// Creative Commons Attribution-NonCommercial (CC BY-NC) +// or +// MIT License +// at your choice. +// +// SPDX-License-Identifier: MIT OR CC-BY-NC-4.0 +// +// ///// +// +// CC-BY-NC-4.0 +// https://creatifloatommons.org/licenses/by-nc/4.0/legalcode +// https://creatifloatommons.org/licenses/by-nc/4.0/ +// +// ///// +// +// MIT License +// +// Copyright (c) 2011-2021 Mercury Demogroup +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. +// +// ///// +// +//////////////////////////////////////////////////////////////// +// +// How to use this: +// +// 1. Build some system to #include glsl files in each other. +// Include this one at the very start. Or just paste everywhere. +// 2. Build a sphere tracer. See those papers: +// * "Sphere Tracing" https://link.springer.com/article/10.1007%2Fs003710050084 +// * "Enhanced Sphere Tracing" http://diglib.eg.org/handle/10.2312/stag.20141233.001-008 +// * "Improved Ray Casting of Procedural Distance Bounds" https://www.bibsonomy.org/bibtex/258e85442234c3ace18ba4d89de94e57d +// The Raymnarching Toolbox Thread on pouet can be helpful as well +// http://www.pouet.net/topic.php?which=7931&page=1 +// and contains links to many more resources. +// 3. Use the tools in this library to build your distance bound f(). +// 4. ??? +// 5. Win a compo. +// +// (6. Buy us a beer or a good vodka or something, if you like.) +// +//////////////////////////////////////////////////////////////// +// +// Table of Contents: +// +// * Helper functions and macros +// * Collection of some primitive objects +// * Domain Manipulation operators +// * Object combination operators +// +//////////////////////////////////////////////////////////////// +// +// Why use this? +// +// The point of this lib is that everything is structured according +// to patterns that we ended up using when building geometry. +// It makes it more easy to write code that is reusable and that somebody +// else can actually understand. Especially code on Shadertoy (which seems +// to be what everybody else is looking at for "inspiration") tends to be +// really ugly. So we were forced to do something about the situation and +// release this lib ;) +// +// Everything in here can probably be done in some better way. +// Please experiment. We'd love some feedback, especially if you +// use it in a scene production. +// +// The main patterns for building geometry this way are: +// * Stay Lipschitz continuous. That means: don't have any distance +// gradient larger than 1. Try to be as close to 1 as possible - +// Distances are euclidean distances, don't fudge around. +// Underestimating distances will happen. That's why calling +// it a "distance bound" is more correct. Don't ever multiply +// distances by some value to "fix" a Lipschitz continuity +// violation. The invariant is: each fSomething() function returns +// a correct distance bound. +// * Use very few primitives and combine them as building blocks +// using combine opertors that preserve the invariant. +// * Multiply objects by repeating the domain (space). +// If you are using a loop inside your distance function, you are +// probably doing it wrong (or you are building boring fractals). +// * At right-angle intersections between objects, build a new local +// coordinate system from the two distances to combine them in +// interesting ways. +// * As usual, there are always times when it is best to not follow +// specific patterns. +// +//////////////////////////////////////////////////////////////// +// +// FAQ +// +// Q: Why is there no sphere tracing code in this lib? +// A: Because our system is way too complex and always changing. +// This is the constant part. Also we'd like everyone to +// explore for themselves. +// +// Q: This does not work when I paste it into Shadertoy!!!! +// A: Yes. It is GLSL, not GLSL ES. We like real OpenGL +// because it has way more features and is more likely +// to work compared to browser-based WebGL. We recommend +// you consider using OpenGL for your productions. Most +// of this can be ported easily though. +// +// Q: How do I material? +// A: We recommend something like this: +// Write a material ID, the distance and the local coordinate +// p into some global variables whenever an object's distance is +// smaller than the stored distance. Then, at the end, evaluate +// the material to get color, roughness, etc., and do the shading. +// +// Q: I found an error. Or I made some function that would fit in +// in this lib. Or I have some suggestion. +// A: Awesome! Drop us a mail at spheretracing@mercury.sexy. +// +// Q: Why is this not on github? +// A: Because we were too lazy. If we get bugged about it enough, +// we'll do it. +// +// Q: Your license sucks for me. +// A: Oh. What should we change it to? +// +// Q: I have trouble understanding what is going on with my distances. +// A: Some visualization of the distance field helps. Try drawing a +// plane that you can sweep through your scene with some color +// representation of the distance field at each point and/or iso +// lines at regular intervals. Visualizing the length of the +// gradient (or better: how much it deviates from being equal to 1) +// is immensely helpful for understanding which parts of the +// distance field are broken. +// +//////////////////////////////////////////////////////////////// + +#define PI 3.14159265 + +// Repeat around the origin by a fixed angle. +// For easier use, num of repetitions is use to specify the angle. +float pModPolar(inout float2 p, float repetitions) { + float angle = 2*PI/repetitions; + float a = atan2(p.y, p.x) + angle/2.; + float r = length(p); + float c = floor(a/angle); + a = glsl_mod(a,angle) - angle/2.; + p = float2(cos(a), sin(a))*r; + // For an odd number of repetitions, fix cell index of the cell in -x direction + // (cell index would be e.g. -5 and 5 in the two halves of the cell): + if (abs(c) >= (repetitions/2)) c = abs(c); + return c; +} + +#endif // __HG_SDF__ |