64 lines
2.1 KiB
Zig
64 lines
2.1 KiB
Zig
const std = @import("std");
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pub const tan = std.math.tan;
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pub const cos = std.math.cos;
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pub const sin = std.math.sin;
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pub const rad = std.math.degreesToRadians;
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pub const Matrix = struct {
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rows: [4]@Vector(4, f32),
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pub fn lookAt(eye: @Vector(3, f32), target: @Vector(3, f32), arbitrary_up: @Vector(3, f32)) Matrix {
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const forward = normalize(eye - target);
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const right = normalize(cross(arbitrary_up, forward));
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const up = cross(forward, right);
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const view = [_]@Vector(4, f32){
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@Vector(4, f32){ right[0], right[1], right[2], 0.0 },
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@Vector(4, f32){ up[0], up[1], up[2], 0.0 },
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@Vector(4, f32){ forward[0], forward[1], forward[2], 0.0 },
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@Vector(4, f32){ 0.0, 0.0, 1.0, eye[2] },
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};
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return Matrix{
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.rows = view,
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};
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}
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pub fn perspective(fov: f32, aspect: f32, near: f32, far: f32) Matrix {
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const projection = [_]@Vector(4, f32){
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@Vector(4, f32){ 1.0 / (aspect * tan(fov / 2.0)), 0.0, 0.0, 0.0 },
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@Vector(4, f32){ 0.0, 1.0 / tan(fov / 2.0), 0.0, 0.0 },
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@Vector(4, f32){ 0.0, 0.0, -((far + near) / (far - near)), -((2 * far * near) / (far - near)) },
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@Vector(4, f32){ 0.0, 0.0, -1.0, 1.0 },
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};
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return Matrix{
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.rows = projection,
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};
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}
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pub fn identity() Matrix {
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const view = [_]@Vector(4, f32){
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@Vector(4, f32){ 1.0, 0.0, 0.0, 0.0 },
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@Vector(4, f32){ 0.0, 1.0, 0.0, 0.0 },
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@Vector(4, f32){ 0.0, 0.0, 1.0, 0.0 },
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@Vector(4, f32){ 0.0, 0.0, 0.0, 1.0 },
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};
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return Matrix{
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.rows = view,
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};
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}
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};
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pub fn dot(a: @Vector(3, f32), b: @Vector(3, f32)) f32 {
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return @reduce(.Add, a * b);
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}
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pub fn cross(a: @Vector(3, f32), b: @Vector(3, f32)) @Vector(3, f32) {
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return @Vector(3, f32){ a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0] };
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}
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pub fn normalize(a: @Vector(3, f32)) @Vector(3, f32) {
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return a / @as(@Vector(3, f32), @splat(@sqrt(dot(a, a))));
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}
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