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#version 300 es
precision mediump float;
/*
* SPDX-FileCopyrightText: syuilo and misskey-project
* SPDX-License-Identifier: AGPL-3.0-only
*/
const float PI = 3.141592653589793;
const float TWO_PI = 6.283185307179586;
const float HALF_PI = 1.5707963267948966;
in vec2 in_uv;
uniform sampler2D in_texture;
uniform vec2 in_resolution;
uniform vec2 u_offset;
uniform vec2 u_scale;
uniform bool u_ellipse;
uniform float u_angle;
uniform float u_radius;
uniform int u_samples;
out vec4 out_color;
float rand(vec2 value) {
return fract(sin(dot(value, vec2(12.9898, 78.233))) * 43758.5453);
}
void main() {
float angle = -(u_angle * PI);
float aspect = in_resolution.x / max(in_resolution.y, 1.0);
vec2 centeredUv = in_uv - vec2(0.5, 0.5) - u_offset;
vec2 scaledUv = vec2(centeredUv.x * aspect, centeredUv.y);
vec2 rotatedScaledUv = vec2(
scaledUv.x * cos(angle) - scaledUv.y * sin(angle),
scaledUv.x * sin(angle) + scaledUv.y * cos(angle)
);
vec2 rotatedUV = vec2(rotatedScaledUv.x / aspect, rotatedScaledUv.y) + u_offset;
bool isInside = false;
if (u_ellipse) {
vec2 norm = (rotatedUV - u_offset) / u_scale;
isInside = dot(norm, norm) <= 1.0;
} else {
isInside = rotatedUV.x > u_offset.x - u_scale.x && rotatedUV.x < u_offset.x + u_scale.x && rotatedUV.y > u_offset.y - u_scale.y && rotatedUV.y < u_offset.y + u_scale.y;
}
if (!isInside) {
out_color = texture(in_texture, in_uv);
return;
}
vec4 result = vec4(0.0);
float totalSamples = 0.0;
// Make blur radius resolution-independent by using a percentage of image size
float referenceSize = min(in_resolution.x, in_resolution.y);
float normalizedRadius = u_radius / 100.0;
float radiusPx = normalizedRadius * referenceSize;
vec2 texelSize = 1.0 / in_resolution;
int sampleCount = max(u_samples, 1);
float sampleCountF = float(sampleCount);
float jitter = rand(in_uv * in_resolution);
float goldenAngle = 2.39996323;
// Sample in a circular pattern to avoid axis-aligned artifacts
for (int i = 0; i < sampleCount; i++) {
float fi = float(i);
float radius = sqrt((fi + 0.5) / sampleCountF);
float theta = (fi + jitter) * goldenAngle;
vec2 direction = vec2(cos(theta), sin(theta));
vec2 offset = direction * (radiusPx * radius) * texelSize;
vec2 sampleUV = in_uv + offset;
if (sampleUV.x >= 0.0 && sampleUV.x <= 1.0 && sampleUV.y >= 0.0 && sampleUV.y <= 1.0) {
float weight = exp(-radius * radius * 4.0);
result += texture(in_texture, sampleUV) * weight;
totalSamples += weight;
}
}
out_color = totalSamples > 0.0 ? result / totalSamples : texture(in_texture, in_uv);
}
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