yum-mirror/slang

Making it easier to work with shaders

git clone https://git.yummers.dev/yum-mirror/slang

Matthew MoultonImprove documentation and example formatting consistency (#4299)78d34f3b3

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1// example-effect.slang
2
3// This file provides an example of how a shader
4// toy effect can be compiled as a Slang module.
5//
6// Every effect will depend on the module that
7// defines out shader toy infrastructure:
8//
9import shader_toy;
10
11// The `shader_toy` module defines the interface
12// that each effect must implement, and our
13// specific effect will be a type that implements
14// the interface:
15//
16struct ExampleEffect : IShaderToyImageShader
17{
18    // Our goal is that we can mostly just copy-paste
19    // the code for an effect from shadertoy.com into
20    // this file, and have something that works.
21    //
22    // Due to limitations in compatibility between
23    // GLSL and Slang, that won't always work, but
24    // it still helps to note where the original
25    // GLSL code begins/ends.
26
27    // Note: the verison of this file that is checked
28    // in uses a placeholder effect so that this file
29    // does not need to concern itself with the license
30    // terms of particular effects on shadertoy.com.
31
32// BEGIN GLSL
33
34float rand(float n)
35{
36    return fract(sin(n) * 43758.5453123);
37}
38
39void mainImage(out vec4 fragColor, in vec2 fragCoord)
40{
41    float screenScale = length(iResolution.xy);
42    vec2 uv = fragCoord / screenScale;
43
44    float frequency = 5.0f;
45    vec2 pos = (uv + iTime*vec2(0.25f, 0.0f)) * frequency;
46
47    vec2 center = floor(pos + vec2(0.5));
48
49    float r0 = rand(center.x*3.0f  + center.y*7.0f);
50    float r1 = rand(center.x*7.0f  + center.y*13.0f);
51    float r2 = rand(center.x*13.0f + center.y*3.0f);
52
53    float p = mix(0.0f, 4.0f, r0);
54    float f = mix(5.0f, 8.0f, r1);
55
56    float a = 0.5f * (1.0f + cos(iTime*f + p));
57
58    float rad0 = mix(0.1, 0.4, r2);
59    float rad1 = mix(0.2, 0.9, r0);
60
61    float radius = 0.5f*mix(rad0, rad1, a);
62
63    vec2 delta = pos - center;
64    float distance = length(delta);
65
66    fragColor.xyz = vec3(r0, r1, r2);
67    fragColor.w = 1.0f;
68
69    if(distance > radius) fragColor.xyz = vec3(0.25f);
70}
71
72// END GLSL
73
74    // The GLSL logic for the effect above might have included
75    // "global" declarations (which become fields since things
76    // are wrapped in a `struct`) with initializer, and we
77    // need a way for the code that uses an effect like this
78    // to get an instance that has been properly initialized.
79    //
80    // Right now, the `IShaderToyImageShader` interface requires
81    // a factory function `getDefault()`, so we will implement
82    // that here.
83    //
84    static This getDefault()
85    {
86        // Note: this code does not need to be updated for different
87        // GLSL effects, since it will default-initialize whatever
88        // members the `This` types has.
89        //
90        This value = {};
91        return value;
92    }
93}