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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
//
// blurredPoints.metal
// OHarkonnen
//
// Created by Nishant Bhasin on 2025-03-11.
//
#include <metal_stdlib>
using namespace metal;
struct VertexOut {
float4 position [[position]];
float2 texCoord;
};
vertex VertexOut milky_way_vertex(uint vertexID [[vertex_id]]) {
float2 positions[4] = {
{-1, -1}, // Bottom-left
{ 1, -1}, // Bottom-right
{-1, 1}, // Top-left
{ 1, 1} // Top-right
};
float2 texCoords[4] = {
{0, 0}, // Bottom-left
{1, 0}, // Bottom-right
{0, 1}, // Top-left
{1, 1} // Top-right
};
VertexOut out;
out.position = float4(positions[vertexID], 0, 1);
out.texCoord = texCoords[vertexID];
return out;
}
// ✅ Made static to avoid linker conflicts
static float random(float2 p) {
return fract(sin(dot(p, float2(127.1, 311.7))) * 43758.5453);
}
static float noise(float2 p) {
float2 i = floor(p);
float2 f = fract(p);
float a = random(i);
float b = random(i + float2(1.0, 0.0));
float c = random(i + float2(0.0, 1.0));
float2 u = f * f * (3.0 - 2.0 * f);
return mix(a, b, u.x) + (c - a) * u.y * (b - a) * u.x;
}
fragment half4 milky_way_fragment(VertexOut in [[stage_in]],
constant float &time [[buffer(0)]],
texture2d<half> previousFrame [[texture(0)]]) {
// Five animated control points
float2 p1 = float2(0.2 + 0.2 * sin(time * 0.8), 0.3 + 0.2 * cos(time * 0.8));
float2 p2 = float2(0.8 + 0.2 * cos(time * 0.6), 0.7 + 0.2 * sin(time * 0.6));
float2 p3 = float2(0.6 + 0.2 * sin(time * 1.5), 0.3 + 0.2 * cos(time * 1.5));
float2 p4 = float2(0.4 + 0.2 * cos(time * 1.1), 0.6 + 0.2 * sin(time * 1.1));
float2 p5 = float2(0.7 + 0.2 * sin(time * 0.9), 0.5 + 0.2 * cos(time * 0.9));
// Colors for each control point
half3 color1 = half3(1.0, 0.47, 0.2);
half3 color2 = half3(0.2, 0.55, 1.0);
half3 color3 = half3(1.0, 0.31, 0.12);
half3 color4 = half3(0.5, 1.0, 0.4);
half3 color5 = half3(0.8, 0.2, 0.6);
// Pulsating effect
float sizeMod = 0.1 + 0.05 * sin(time * 1.2);
float maxDistance = 0.725 + sizeMod;
// Influence calculation
float d1 = pow(max(1.0 - distance(in.texCoord, p1) / maxDistance, 0.0), 2.0);
float d2 = pow(max(1.0 - distance(in.texCoord, p2) / maxDistance, 0.0), 2.0);
float d3 = pow(max(1.0 - distance(in.texCoord, p3) / maxDistance, 0.0), 2.0);
float d4 = pow(max(1.0 - distance(in.texCoord, p4) / maxDistance, 0.0), 2.0);
float d5 = pow(max(1.0 - distance(in.texCoord, p5) / maxDistance, 0.0), 2.0);
// Add Perlin noise to influence size
float noiseMod = noise(in.texCoord * 10.0 + time) * 0.1;
maxDistance += noiseMod;
// Normalize weights
float totalWeight = d1 + d2 + d3 + d4 + d5;
if (totalWeight > 0.001) {
d1 /= totalWeight;
d2 /= totalWeight;
d3 /= totalWeight;
d4 /= totalWeight;
d5 /= totalWeight;
}
// Blend colors based on influence
half3 blendedColor = d1 * color1 + d2 * color2 + d3 * color3 + d4 * color4 + d5 * color5;
// Sample the previous frame for motion blur
half4 lastFrameColor = previousFrame.sample(sampler(coord::normalized), in.texCoord);
// Apply motion blur by mixing with the last frame
half4 finalColor = half4(mix(lastFrameColor.rgb, blendedColor, 0.85), 1.0); // 85% current frame
return finalColor;
}