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math: add matrix transposition

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2023-09-08 21:47:13 -07:00
parent 5dda26960d
commit 7e8e1c03b9
1 changed files with 48 additions and 1 deletions
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49
src/math/mat.zig
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@ -102,6 +102,15 @@ pub fn Mat(
return RowVec.init(m.v[i].v[0], m.v[i].v[1], m.v[i].v[2]);
}
/// Transposes the matrix.
pub inline fn transpose(m: Matrix) Matrix {
return .{ .v = [_]Vec{
Vec.init(m.v[0].v[0], m.v[1].v[0], m.v[2].v[0], 1),
Vec.init(m.v[0].v[1], m.v[1].v[1], m.v[2].v[1], 1),
Vec.init(m.v[0].v[2], m.v[1].v[2], m.v[2].v[2], 1),
} };
}
/// Constructs a 2D matrix which scales each dimension by the given vector.
// TODO: needs tests
pub inline fn scale(s: math.Vec2) Matrix {
@ -163,7 +172,7 @@ pub fn Mat(
/// ```
///
/// Note that Mach matrices use [column-major storage and column-vectors](https://machengine.org/engine/math/matrix-storage/).
pub inline fn init(r0: Vec, r1: RowVec, r2: RowVec, r3: RowVec) Matrix {
pub inline fn init(r0: RowVec, r1: RowVec, r2: RowVec, r3: RowVec) Matrix {
return .{ .v = [_]Vec{
Vec.init(r0.x(), r1.x(), r2.x(), r3.x()),
Vec.init(r0.y(), r1.y(), r2.y(), r3.y()),
@ -182,6 +191,16 @@ pub fn Mat(
return RowVec.init(m.v[i].v[0], m.v[i].v[1], m.v[i].v[2], m.v[i].v[3]);
}
/// Transposes the matrix.
pub inline fn transpose(m: Matrix) Matrix {
return .{ .v = [_]Vec{
Vec.init(m.v[0].v[0], m.v[1].v[0], m.v[2].v[0], m.v[3].v[0]),
Vec.init(m.v[0].v[1], m.v[1].v[1], m.v[2].v[1], m.v[3].v[1]),
Vec.init(m.v[0].v[2], m.v[1].v[2], m.v[2].v[2], m.v[3].v[2]),
Vec.init(m.v[0].v[3], m.v[1].v[3], m.v[2].v[3], m.v[3].v[3]),
} };
}
/// Constructs a 3D matrix which scales each dimension by the given vector.
// TODO: needs tests
pub inline fn scale(s: math.Vec3) Matrix {
@ -536,6 +555,34 @@ test "Mat4x4_col" {
try testing.expect(math.Vec4, math.vec4(3, 7, 11, 15)).eql(m.col(@TypeOf(m).cols - 1));
}
test "Mat3x3_transpose" {
const m = math.Mat3x3.init(
math.vec3(0, 1, 2),
math.vec3(3, 4, 5),
math.vec3(6, 7, 8),
);
try testing.expect(math.Mat3x3, math.Mat3x3.init(
math.vec3(0, 3, 6),
math.vec3(1, 4, 7),
math.vec3(2, 5, 8),
)).eql(m.transpose());
}
test "Mat4x4_transpose" {
const m = math.Mat4x4.init(
math.vec4(0, 1, 2, 3),
math.vec4(4, 5, 6, 7),
math.vec4(8, 9, 10, 11),
math.vec4(12, 13, 14, 15),
);
try testing.expect(math.Mat4x4, math.Mat4x4.init(
math.vec4(0, 4, 8, 12),
math.vec4(1, 5, 9, 13),
math.vec4(2, 6, 10, 14),
math.vec4(3, 7, 11, 15),
)).eql(m.transpose());
}
// TODO(math): the tests below violate our styleguide (https://machengine.org/about/style/) we
// should write new tests loosely based on them: