53 lines
2 KiB
GLSL
53 lines
2 KiB
GLSL
#include "../math/const.glsl"
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#include "../sampler.glsl"
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/*
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contributors: Patricio Gonzalez Vivo
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description: Pincushion distortion
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use: barrel(SAMPLER_TYPE tex, <vec2> st [, <vec2|float> distance])
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options:
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- SAMPLER_FNC(TEX, UV): optional depending the target version of GLSL (texture2D(...) or texture(...))
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- PINCUSHION_TYPE: return type, defaults to vec3
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- PINCUSHION_SAMPLER_FNC: function used to sample the input texture, defaults to texture2D(TEX, UV).rgb
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- PINCUSHION_OCT_1: one octave of distortion
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- PINCUSHION_OCT_2: two octaves of distortion
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- PINCUSHION_OCT_3: three octaves of distortion
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examples:
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- https://raw.githubusercontent.com/eduardfossas/lygia-study-examples/main/distort/barrel.frag
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license:
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- Copyright (c) 2021 Patricio Gonzalez Vivo under Prosperity License - https://prosperitylicense.com/versions/3.0.0
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- Copyright (c) 2021 Patricio Gonzalez Vivo under Patron License - https://lygia.xyz/license
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*/
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#ifndef PINCUSHION_TYPE
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#define PINCUSHION_TYPE vec3
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#endif
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#ifndef PINCUSHION_SAMPLER_FNC
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#define PINCUSHION_SAMPLER_FNC(TEX, UV) SAMPLER_FNC(TEX, UV).rgb
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#endif
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#ifndef FNC_PINCUSHION
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#define FNC_PINCUSHION
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vec2 pincushion(vec2 st, vec2 pixel, float amt) {
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float prop = pixel.x / pixel.y; // screen proroption
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vec2 m = vec2(0.5, 0.5 / prop); // center coords
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vec2 d = st - m; // vector from center to current fragment
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float dist = sqrt(dot(d, d)); // distance of pixel from center
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float power = (TAU / (2.0 * sqrt(dot(m, m)))) * -amt;
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float bind = (prop < 1.0)? m.x : m.y;
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float A = (power > 0.0)? tan(dist * power) : atan(dist * -power * 10.0);
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float B = (power > 0.0)? tan(bind * power) : atan(-power * bind * 10.0);
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vec2 uv = m + normalize(d) * A * bind/B;
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return vec2(uv.x, uv.y * prop);
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}
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PINCUSHION_TYPE pincushion(SAMPLER_TYPE tex, vec2 st, vec2 pixel, float amt) {
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vec2 uv = pincushion(st, pixel, amt);
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return PINCUSHION_SAMPLER_FNC(tex, uv);
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}
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#endif
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