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const std = @import("std");
const rl = @import("raylib");
const particle = struct {
colorId: u32,
attrs: particleAttrs,
x: i32,
y: i32,
xvel: f32,
yvel: f32,
};
const particleAttrs = struct {};
const screenWidth = 2560;
const screenHeight = 1440;
const particleMax = 5000;
const radius = 100.0;
const minDistance = 20.0;
const colors = [_]rl.Color{
rl.Color.red,
rl.Color.green,
rl.Color.blue,
rl.Color.yellow,
rl.Color.magenta,
rl.Color.brown,
rl.Color.orange,
};
const colorAmnt = colors.len;
pub fn main() !void {
const rules = ruleMatrix(colors.len);
printRules(rules);
rl.initWindow(screenWidth, screenHeight, "Particle Simulator");
defer rl.closeWindow();
rl.setTargetFPS(60);
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
var particles = try initParticles(gpa.allocator(), 3000);
defer particles.deinit(gpa.allocator());
while (!rl.windowShouldClose()) {
rl.beginDrawing();
if (rl.isKeyPressed(rl.KeyboardKey.key_q)) break;
defer rl.endDrawing();
updateVelocities(particles, rules);
for (particles.items(.y), particles.items(.yvel)) |*y, yvel|
y.* = @mod(@as(i32, @intFromFloat(@round((@as(f32, @floatFromInt(y.*)) + yvel)))), screenHeight);
for (particles.items(.x), particles.items(.xvel)) |*x, xvel|
x.* = @mod(@as(i32, @intFromFloat(@round((@as(f32, @floatFromInt(x.*)) + xvel)))), screenWidth);
for (particles.items(.y), particles.items(.x), particles.items(.colorId)) |*y, *x, colorId|
rl.drawRectangle(x.*, y.*, 5, 5, colors[colorId]);
rl.clearBackground(rl.Color.black);
}
}
fn colorToString(c: usize) []const u8 {
return switch (c) {
0 => "R",
1 => "G",
2 => "Bl",
3 => "Y",
4 => "M",
5 => "Br",
6 => "O",
else => " ",
};
}
fn printRules(rules: [colorAmnt][colorAmnt]f32) void {
std.debug.print("\n|{s:^6}", .{"Rules"});
for (0..colors.len) |c|
std.debug.print("| {s:^4} ", .{colorToString(c)});
std.debug.print("|\n", .{});
for (rules, 0..) |row, i| {
std.debug.print("| {s:^4} ", .{colorToString(i)});
for (row) |col|
std.debug.print("| {d:^4.1} ", .{col});
std.debug.print("|\n", .{});
}
}
fn force(distance: f32, attraction: f32) f32 {
const beta = minDistance / radius;
const r: f32 = distance / radius;
if (r < beta)
return -(r / beta - 1.0);
if (beta <= r and r < 1)
return attraction * (1 - @abs(2.0 * r - 1.0 - beta) / (1.0 - beta));
return 0;
}
fn updateVelocities(particles: std.MultiArrayList(particle), rules: [colorAmnt][colorAmnt]f32) void {
const colorList = particles.items(.colorId);
var xvel = particles.items(.xvel);
var yvel = particles.items(.yvel);
for (particles.items(.x), particles.items(.y), 0..) |x, y, i| {
var forceX: f32 = 0.0;
var forceY: f32 = 0.0;
for (particles.items(.x), particles.items(.y), 0..) |x2, y2, j| {
if (i == j) continue;
const rx: f32 = @floatFromInt(x - x2);
const ry: f32 = @floatFromInt(y - y2);
var r = @sqrt(rx * rx + ry * ry);
if (r == 0) {
r = 0.0001;
}
if (r > 0 and r < radius) {
const f = force(r, rules[colorList[i]][colorList[j]]);
forceX = forceX + rx / r * f;
forceY = forceY + ry / r * f;
}
}
forceX = forceX * minDistance / radius;
forceY = forceY * minDistance / radius;
xvel[i] = xvel[i] * 0.95 + forceX;
yvel[i] = yvel[i] * 0.95 + forceY;
}
}
/// Generates a particle with a random Color and Location
pub fn createParticle(attrs: particleAttrs) particle {
const seed = @as(u64, @truncate(@as(u128, @bitCast(std.time.nanoTimestamp()))));
var prng = std.rand.DefaultPrng.init(seed);
const x = prng.random().uintLessThan(u32, screenWidth);
const y = prng.random().uintLessThan(u32, screenHeight);
const color = prng.random().uintLessThan(u32, colorAmnt);
return particle{
.colorId = color,
.attrs = attrs,
.x = @intCast(x),
.y = @intCast(y),
.xvel = 0,
.yvel = 0,
};
}
fn ruleMatrix(comptime size: u32) [size][size]f32 {
const seed = @as(u64, @truncate(@as(u128, @bitCast(std.time.nanoTimestamp()))));
var prng = std.rand.DefaultPrng.init(seed);
var rules: [size][size]f32 = undefined;
for (0..size) |i| {
for (0..size) |j| {
var val = prng.random().float(f32);
const isNeg = prng.random().uintAtMost(u8, 1);
if (isNeg == 1) val = 0 - val;
rules[i][j] = val;
}
}
return rules;
}
/// Initialize a MultiArrayList of size amnt with particles created by createParticle
pub fn initParticles(allocator: std.mem.Allocator, amnt: u32) !std.MultiArrayList(particle) {
var particles = std.MultiArrayList(particle){};
try particles.setCapacity(allocator, 10000);
for (0..amnt) |_| {
try particles.append(allocator, createParticle(.{}));
}
return particles;
}
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