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Add Matrix4.leftMultiply for left multiplication in-place #354

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e5caaaf
left-multiply
LongCatIsLooong Nov 3, 2025
3465ae9
Undo format changes
LongCatIsLooong Nov 3, 2025
62cfcb7
remove type annotations
LongCatIsLooong Nov 3, 2025
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57 changes: 57 additions & 0 deletions lib/src/vector_math/matrix4.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -1760,6 +1760,63 @@ class Matrix4 {
_m4storage[15] = (m30 * n03) + (m31 * n13) + (m32 * n23) + (m33 * n33);
}

/// Computes the result of `arg x this` and stores the result in-place in
/// [this].
///
/// This method does not alter the [Matrix4] in `arg`.
void leftMultiply(Matrix4 arg) {
final argStorage = arg._m4storage;
final m00 = argStorage[0];
final m01 = argStorage[4];
final m02 = argStorage[8];
final m03 = argStorage[12];
final m10 = argStorage[1];
final m11 = argStorage[5];
final m12 = argStorage[9];
final m13 = argStorage[13];
final m20 = argStorage[2];
final m21 = argStorage[6];
final m22 = argStorage[10];
final m23 = argStorage[14];
final m30 = argStorage[3];
final m31 = argStorage[7];
final m32 = argStorage[11];
final m33 = argStorage[15];
final bStorage = _m4storage;
final n00 = bStorage[0];
final n01 = bStorage[4];
final n02 = bStorage[8];
final n03 = bStorage[12];
final n10 = bStorage[1];
final n11 = bStorage[5];
final n12 = bStorage[9];
final n13 = bStorage[13];
final n20 = bStorage[2];
final n21 = bStorage[6];
final n22 = bStorage[10];
final n23 = bStorage[14];
final n30 = bStorage[3];
final n31 = bStorage[7];
final n32 = bStorage[11];
final n33 = bStorage[15];
bStorage[0] = (m00 * n00) + (m01 * n10) + (m02 * n20) + (m03 * n30);
bStorage[4] = (m00 * n01) + (m01 * n11) + (m02 * n21) + (m03 * n31);
bStorage[8] = (m00 * n02) + (m01 * n12) + (m02 * n22) + (m03 * n32);
bStorage[12] = (m00 * n03) + (m01 * n13) + (m02 * n23) + (m03 * n33);
bStorage[1] = (m10 * n00) + (m11 * n10) + (m12 * n20) + (m13 * n30);
bStorage[5] = (m10 * n01) + (m11 * n11) + (m12 * n21) + (m13 * n31);
bStorage[9] = (m10 * n02) + (m11 * n12) + (m12 * n22) + (m13 * n32);
bStorage[13] = (m10 * n03) + (m11 * n13) + (m12 * n23) + (m13 * n33);
bStorage[2] = (m20 * n00) + (m21 * n10) + (m22 * n20) + (m23 * n30);
bStorage[6] = (m20 * n01) + (m21 * n11) + (m22 * n21) + (m23 * n31);
bStorage[10] = (m20 * n02) + (m21 * n12) + (m22 * n22) + (m23 * n32);
bStorage[14] = (m20 * n03) + (m21 * n13) + (m22 * n23) + (m23 * n33);
bStorage[3] = (m30 * n00) + (m31 * n10) + (m32 * n20) + (m33 * n30);
bStorage[7] = (m30 * n01) + (m31 * n11) + (m32 * n21) + (m33 * n31);
bStorage[11] = (m30 * n02) + (m31 * n12) + (m32 * n22) + (m33 * n32);
bStorage[15] = (m30 * n03) + (m31 * n13) + (m32 * n23) + (m33 * n33);
}

/// Multiply a copy of this with [arg].
Matrix4 multiplied(Matrix4 arg) => clone()..multiply(arg);

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57 changes: 57 additions & 0 deletions lib/src/vector_math_64/matrix4.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -1760,6 +1760,63 @@ class Matrix4 {
_m4storage[15] = (m30 * n03) + (m31 * n13) + (m32 * n23) + (m33 * n33);
}

/// Computes the result of `arg x this` and stores the result in-place in
/// [this].
///
/// This method does not alter the [Matrix4] in `arg`.
void leftMultiply(Matrix4 arg) {
final argStorage = arg._m4storage;
final m00 = argStorage[0];
final m01 = argStorage[4];
final m02 = argStorage[8];
final m03 = argStorage[12];
final m10 = argStorage[1];
final m11 = argStorage[5];
final m12 = argStorage[9];
final m13 = argStorage[13];
final m20 = argStorage[2];
final m21 = argStorage[6];
final m22 = argStorage[10];
final m23 = argStorage[14];
final m30 = argStorage[3];
final m31 = argStorage[7];
final m32 = argStorage[11];
final m33 = argStorage[15];
final bStorage = _m4storage;
final n00 = bStorage[0];
final n01 = bStorage[4];
final n02 = bStorage[8];
final n03 = bStorage[12];
final n10 = bStorage[1];
final n11 = bStorage[5];
final n12 = bStorage[9];
final n13 = bStorage[13];
final n20 = bStorage[2];
final n21 = bStorage[6];
final n22 = bStorage[10];
final n23 = bStorage[14];
final n30 = bStorage[3];
final n31 = bStorage[7];
final n32 = bStorage[11];
final n33 = bStorage[15];
bStorage[0] = (m00 * n00) + (m01 * n10) + (m02 * n20) + (m03 * n30);
bStorage[4] = (m00 * n01) + (m01 * n11) + (m02 * n21) + (m03 * n31);
bStorage[8] = (m00 * n02) + (m01 * n12) + (m02 * n22) + (m03 * n32);
bStorage[12] = (m00 * n03) + (m01 * n13) + (m02 * n23) + (m03 * n33);
bStorage[1] = (m10 * n00) + (m11 * n10) + (m12 * n20) + (m13 * n30);
bStorage[5] = (m10 * n01) + (m11 * n11) + (m12 * n21) + (m13 * n31);
bStorage[9] = (m10 * n02) + (m11 * n12) + (m12 * n22) + (m13 * n32);
bStorage[13] = (m10 * n03) + (m11 * n13) + (m12 * n23) + (m13 * n33);
bStorage[2] = (m20 * n00) + (m21 * n10) + (m22 * n20) + (m23 * n30);
bStorage[6] = (m20 * n01) + (m21 * n11) + (m22 * n21) + (m23 * n31);
bStorage[10] = (m20 * n02) + (m21 * n12) + (m22 * n22) + (m23 * n32);
bStorage[14] = (m20 * n03) + (m21 * n13) + (m22 * n23) + (m23 * n33);
bStorage[3] = (m30 * n00) + (m31 * n10) + (m32 * n20) + (m33 * n30);
bStorage[7] = (m30 * n01) + (m31 * n11) + (m32 * n21) + (m33 * n31);
bStorage[11] = (m30 * n02) + (m31 * n12) + (m32 * n22) + (m33 * n32);
bStorage[15] = (m30 * n03) + (m31 * n13) + (m32 * n23) + (m33 * n33);
}

/// Multiply a copy of this with [arg].
Matrix4 multiplied(Matrix4 arg) => clone()..multiply(arg);

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41 changes: 41 additions & 0 deletions test/matrix4_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -388,6 +388,46 @@ void testMatrix4SelfMultiply() {
}
}

void testMatrix4LeftMultiply() {
final inputA = <Matrix4>[];
final inputB = <Matrix4>[];
final expectedOutput = <Matrix4>[];

inputA.add(
parseMatrix<Matrix4>(
'''0.450541598502498 0.152378018969223 0.078175528753184 0.004634224134067
0.083821377996933 0.825816977489547 0.442678269775446 0.774910464711502
0.228976968716819 0.538342435260057 0.106652770180584 0.817303220653433
0.913337361501670 0.996134716626885 0.961898080855054 0.868694705363510''',
),
);
inputB.add(
parseMatrix<Matrix4>(
'''0.450541598502498 0.152378018969223 0.078175528753184 0.004634224134067
0.083821377996933 0.825816977489547 0.442678269775446 0.774910464711502
0.228976968716819 0.538342435260057 0.106652770180584 0.817303220653433
0.913337361501670 0.996134716626885 0.961898080855054 0.868694705363510''',
),
);
expectedOutput.add(
parseMatrix<Matrix4>(
'''0.237893273152584 0.241190507375353 0.115471053480014 0.188086069635435
0.916103942227480 1.704973929800637 1.164721763902784 1.675285658272358
0.919182849383279 1.351023203753565 1.053750106199745 1.215382950294249
1.508657696357159 2.344965008135463 1.450552688877760 2.316940716769603''',
),
);

assert(inputA.length == inputB.length);
assert(inputB.length == expectedOutput.length);

for (var i = 0; i < inputA.length; i++) {
final output = inputB[i].clone();
output.leftMultiply(inputA[i]);
relativeTest(output, expectedOutput[i]);
}
}

void testMatrix4SelfMultiplyTranspose() {
final inputA = <Matrix4>[];
final inputB = <Matrix4>[];
Expand Down Expand Up @@ -832,6 +872,7 @@ void main() {
test('Determinant', testMatrix4Determinant);
test('Adjoint', testMatrix4Adjoint);
test('Self multiply', testMatrix4SelfMultiply);
test('Left Self multiply', testMatrix4LeftMultiply);
test('Self transpose', testMatrix4SelfTransposeMultiply);
test('Self multiply tranpose', testMatrix4SelfMultiplyTranspose);
test('Matrix multiplication', testMatrix4Multiplication);
Expand Down