95 lines
4.1 KiB
Zig
95 lines
4.1 KiB
Zig
// Made for Zig 0.14.1
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// This implementation works with generic float types
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const std = @import("std");
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const expect = std.testing.expect;
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pub fn main() void {
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std.debug.print("{d}\n", .{noise3D(f64, 3.14, 42, 7)});
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}
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pub fn noise3D(comptime T: type, x: T, y: T, z: T) T {
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// Disable runtime safety to allow the permutation table values to wrap
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@setRuntimeSafety(false);
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// Truncate float to u8 (256 possible values)
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const x_i: u8 = @truncate(@as(usize, @bitCast(@as(isize, @intFromFloat(@floor(x))))));
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const y_i: u8 = @truncate(@as(usize, @bitCast(@as(isize, @intFromFloat(@floor(y))))));
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const z_i: u8 = @truncate(@as(usize, @bitCast(@as(isize, @intFromFloat(@floor(z))))));
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// Float remainder of coords (eg: 5.34 -> 0.34)
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const x_r = x - @floor(x);
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const y_r = y - @floor(y);
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const z_r = z - @floor(z);
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const u = fade(x_r);
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const v = fade(y_r);
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const w = fade(z_r);
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const a = permutation[ x_i ] +% y_i;
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const aa = permutation[ a ] +% z_i;
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const ab = permutation[ a + 1 ] +% z_i;
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const b = permutation[x_i + 1] +% y_i;
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const ba = permutation[ b ] +% z_i;
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const bb = permutation[ b + 1 ] +% z_i;
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// Add blended results from all 8 corners of the cube
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// Use `1.0` instead of `1` to let Zig know it must always be a float value
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return lerp(w, lerp(v, lerp(u, grad3D(T, permutation[ aa ], x_r, y_r, z_r),
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grad3D(T, permutation[ ba ], x_r - 1.0, y_r, z_r)),
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lerp(u, grad3D(T, permutation[ ab ], x_r, y_r - 1.0, z_r),
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grad3D(T, permutation[ bb ], x_r - 1.0, y_r - 1.0, z_r))),
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lerp(v, lerp(u, grad3D(T, permutation[aa + 1], x_r, y_r, z_r - 1.0),
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grad3D(T, permutation[ba + 1], x_r - 1.0, y_r, z_r - 1.0)),
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lerp(u, grad3D(T, permutation[ab + 1], x_r, y_r - 1.0, z_r - 1.0),
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grad3D(T, permutation[bb + 1], x_r - 1.0, y_r - 1.0, z_r - 1.0))));
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}
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fn grad3D(comptime T: type, h: u8, x: T, y: T, z: T) T {
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return switch (h & 15) {
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0, 12 => x + y,
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1, 14 => y - x,
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2 => x - y,
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3 => -x - y,
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4 => x + z,
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5 => z - x,
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6 => x - z,
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7 => -x - z,
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8 => y + z,
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9, 13 => z - y,
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10 => y - z,
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else => -y - z, // 11, 15
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};
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}
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fn lerp(t: anytype, a: anytype, b: anytype) @TypeOf(t, a, b) {
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return a + t * (b - a);
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}
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fn fade(t: anytype) @TypeOf(t) {
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return t * t * t * (t * (6.0 * t - 15.0) + 10.0);
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}
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const permutation = [256]u8{
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151, 160, 137, 91, 90, 15, 131, 13, 201, 95, 96, 53, 194, 233, 7, 225,
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140, 36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23, 190, 6, 148,
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247, 120, 234, 75, 0, 26, 197, 62, 94, 252, 219, 203, 117, 35, 11, 32,
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57, 177, 33, 88, 237, 149, 56, 87, 174, 20, 125, 136, 171, 168, 68, 175,
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74, 165, 71, 134, 139, 48, 27, 166, 77, 146, 158, 231, 83, 111, 229, 122,
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60, 211, 133, 230, 220, 105, 92, 41, 55, 46, 245, 40, 244, 102, 143, 54,
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65, 25, 63, 161, 1, 216, 80, 73, 209, 76, 132, 187, 208, 89, 18, 169,
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200, 196, 135, 130, 116, 188, 159, 86, 164, 100, 109, 198, 173, 186, 3, 64,
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52, 217, 226, 250, 124, 123, 5, 202, 38, 147, 118, 126, 255, 82, 85, 212,
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207, 206, 59, 227, 47, 16, 58, 17, 182, 189, 28, 42, 223, 183, 170, 213,
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119, 248, 152, 2, 44, 154, 163, 70, 221, 153, 101, 155, 167, 43, 172, 9,
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129, 22, 39, 253, 19, 98, 108, 110, 79, 113, 224, 232, 178, 185, 112, 104,
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218, 246, 97, 228, 251, 34, 242, 193, 238, 210, 144, 12, 191, 179, 162, 241,
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81, 51, 145, 235, 249, 14, 239, 107, 49, 192, 214, 31, 181, 199, 106, 157,
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184, 84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254, 138, 236, 205, 93,
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222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215, 61, 156, 180,
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};
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test "3D noise" {
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try expect(noise3D(f64, 3.14, 42, 7) == 0.13691995878400012);
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try expect(noise3D(f64, -4.20, 10, 6) == 0.14208000000000043);
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}
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