math: add matrix multiplication
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst
parent
7e8e1c03b9
commit
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1 changed files with 16 additions and 138 deletions
154
src/math/mat.zig
154
src/math/mat.zig
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@ -277,96 +277,26 @@ pub fn Mat(
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else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"),
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else => @compileError("Expected Mat3x3, Mat4x4 found '" ++ @typeName(Matrix) ++ "'"),
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};
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};
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/// Matrix multiplication a*b
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// TODO: needs tests
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pub fn mul(a: Matrix, b: Matrix) Matrix {
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var result: Matrix = undefined;
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inline for (0..Matrix.rows) |row| {
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inline for (0..Matrix.cols) |col| {
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var sum: RowVec.T = 0.0;
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inline for (0..RowVec.n) |i| {
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sum += a.row(row).mul(b.col(col)).v[i];
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}
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result.v[col].v[row] = sum;
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}
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}
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return result;
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}
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// TODO: the below code was correct in our old implementation, it just needs to be updated
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// TODO: the below code was correct in our old implementation, it just needs to be updated
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// to work with this new Mat approach, swapping f32 for the generic T float type, moving 3x3
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// to work with this new Mat approach, swapping f32 for the generic T float type, moving 3x3
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// and 4x4 specific functions into the mixin above, writing new tests, etc.
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// and 4x4 specific functions into the mixin above, writing new tests, etc.
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// // Multiplies matrices a * b
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// pub inline fn mul(a: anytype, b: @TypeOf(a)) @TypeOf(a) {
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// return if (@TypeOf(a) == Mat3x3) {
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// const a00 = a[0][0];
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// const a01 = a[0][1];
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// const a02 = a[0][2];
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// const a10 = a[1][0];
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// const a11 = a[1][1];
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// const a12 = a[1][2];
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// const a20 = a[2][0];
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// const a21 = a[2][1];
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// const a22 = a[2][2];
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// const b00 = b[0][0];
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// const b01 = b[0][1];
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// const b02 = b[0][2];
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// const b10 = b[1][0];
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// const b11 = b[1][1];
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// const b12 = b[1][2];
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// const b20 = b[2][0];
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// const b21 = b[2][1];
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// const b22 = b[2][2];
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// return init(Mat3x3, .{
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// a00 * b00 + a10 * b01 + a20 * b02,
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// a01 * b00 + a11 * b01 + a21 * b02,
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// a02 * b00 + a12 * b01 + a22 * b02,
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// a00 * b10 + a10 * b11 + a20 * b12,
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// a01 * b10 + a11 * b11 + a21 * b12,
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// a02 * b10 + a12 * b11 + a22 * b12,
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// a00 * b20 + a10 * b21 + a20 * b22,
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// a01 * b20 + a11 * b21 + a21 * b22,
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// a02 * b20 + a12 * b21 + a22 * b22,
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// });
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// } else if (@TypeOf(a) == Mat4x4) {
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// const a00 = a[0][0];
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// const a01 = a[0][1];
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// const a02 = a[0][2];
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// const a03 = a[0][3];
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// const a10 = a[1][0];
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// const a11 = a[1][1];
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// const a12 = a[1][2];
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// const a13 = a[1][3];
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// const a20 = a[2][0];
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// const a21 = a[2][1];
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// const a22 = a[2][2];
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// const a23 = a[2][3];
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// const a30 = a[3][0];
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// const a31 = a[3][1];
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// const a32 = a[3][2];
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// const a33 = a[3][3];
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// const b00 = b[0][0];
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// const b01 = b[0][1];
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// const b02 = b[0][2];
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// const b03 = b[0][3];
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// const b10 = b[1][0];
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// const b11 = b[1][1];
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// const b12 = b[1][2];
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// const b13 = b[1][3];
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// const b20 = b[2][0];
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// const b21 = b[2][1];
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// const b22 = b[2][2];
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// const b23 = b[2][3];
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// const b30 = b[3][0];
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// const b31 = b[3][1];
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// const b32 = b[3][2];
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// const b33 = b[3][3];
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// return init(Mat4x4, .{
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// a00 * b00 + a10 * b01 + a20 * b02 + a30 * b03,
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// a01 * b00 + a11 * b01 + a21 * b02 + a31 * b03,
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// a02 * b00 + a12 * b01 + a22 * b02 + a32 * b03,
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// a03 * b00 + a13 * b01 + a23 * b02 + a33 * b03,
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// a00 * b10 + a10 * b11 + a20 * b12 + a30 * b13,
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// a01 * b10 + a11 * b11 + a21 * b12 + a31 * b13,
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// a02 * b10 + a12 * b11 + a22 * b12 + a32 * b13,
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// a03 * b10 + a13 * b11 + a23 * b12 + a33 * b13,
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// a00 * b20 + a10 * b21 + a20 * b22 + a30 * b23,
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// a01 * b20 + a11 * b21 + a21 * b22 + a31 * b23,
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// a02 * b20 + a12 * b21 + a22 * b22 + a32 * b23,
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// a03 * b20 + a13 * b21 + a23 * b22 + a33 * b23,
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// a00 * b30 + a10 * b31 + a20 * b32 + a30 * b33,
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// a01 * b30 + a11 * b31 + a21 * b32 + a31 * b33,
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// a02 * b30 + a12 * b31 + a22 * b32 + a32 * b33,
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// a03 * b30 + a13 * b31 + a23 * b32 + a33 * b33,
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// });
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// } else @compileError("Expected matrix, found '" ++ @typeName(@TypeOf(a)) ++ "'");
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// }
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// /// Check if two matrices are approximate equal. Returns true if the absolute difference between
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// /// Check if two matrices are approximate equal. Returns true if the absolute difference between
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// /// each element in matrix them is less or equal than the specified tolerance.
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// /// each element in matrix them is less or equal than the specified tolerance.
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// pub inline fn equals(a: anytype, b: @TypeOf(a), tolerance: f32) bool {
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// pub inline fn equals(a: anytype, b: @TypeOf(a), tolerance: f32) bool {
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@ -816,55 +746,3 @@ test "Mat4x4_transpose" {
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// }
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// }
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// }
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// }
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// }
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// }
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// test "mat.mul" {
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// {
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// const tolerance = 1e-6;
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// const t = Vec3{ 1, 2, -3 };
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// const T = mat.translate3d(t);
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// const s = Vec3{ 3, 1, -5 };
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// const S = mat.scale3d(s);
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// const r = Vec3{ 30, -40, 235 };
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// const R_x = mat.rotateX(degreesToRadians(f32, r[0]));
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// const R_y = mat.rotateY(degreesToRadians(f32, r[1]));
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// const R_z = mat.rotateZ(degreesToRadians(f32, r[2]));
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// const R_yz = mat.mul(R_y, R_z);
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// // This values are calculated by hand with help of matrix calculator: https://matrix.reshish.com/multCalculation.php
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// const expected_R_yz = mat.init(Mat4x4, .{
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// -0.43938504177070496278, -0.8191520442889918, -0.36868782649461236545, 0,
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// 0.62750687159713312638, -0.573576436351046, 0.52654078451836329713, 0,
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// -0.6427876096865394, 0, 0.766044443118978, 0,
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// 0, 0, 0, 1,
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// });
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// try expect(mat.equals(R_yz, expected_R_yz, tolerance));
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// const R_xyz = mat.mul(R_x, R_yz);
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// const expected_R_xyz = mat.init(Mat4x4, .{
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// -0.439385041770705, -0.52506256666891627986, -0.72886904595489960019, 0,
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// 0.6275068715971331, -0.76000215715133560834, 0.16920947734596765363, 0,
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// -0.6427876096865394, -0.383022221559489, 0.66341394816893832989, 0,
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// 0, 0, 0, 1,
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// });
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// try expect(mat.equals(R_xyz, expected_R_xyz, tolerance));
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// const SR = mat.mul(S, R_xyz);
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// const expected_SR = mat.init(Mat4x4, .{
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// -1.318155125312115, -0.5250625666689163, 3.6443452297744985, 0,
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// 1.8825206147913993, -0.7600021571513356, -0.8460473867298382, 0,
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// -1.9283628290596182, -0.383022221559489, -3.3170697408446915, 0,
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// 0, 0, 0, 1,
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// });
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// try expect(mat.equals(SR, expected_SR, tolerance));
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// const TSR = mat.mul(T, SR);
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// const expected_TSR = mat.init(Mat4x4, .{
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// -1.318155125312115, -0.5250625666689163, 3.6443452297744985, 0,
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// 1.8825206147913993, -0.7600021571513356, -0.8460473867298382, 0,
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// -1.9283628290596182, -0.383022221559489, -3.3170697408446914, 0,
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// 1, 2, -3, 1,
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// });
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// try expect(mat.equals(TSR, expected_TSR, tolerance));
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// }
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// }
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