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Reduce MatrixMathHelper allocations (#58275) #58275

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86 changes: 54 additions & 32 deletions .../react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/MatrixMathHelper.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@
package com.facebook.react.uimanager

import com.facebook.infer.annotation.Assertions
import kotlin.math.abs
import kotlin.math.atan2
import kotlin.math.cos
import kotlin.math.sin
Expand All @@ -22,11 +21,7 @@ import kotlin.math.tan
public object MatrixMathHelper {
private const val EPSILON = .00001

private fun isZero(d: Double): Boolean {
return if (java.lang.Double.isNaN(d)) {
false
} else abs(d) < EPSILON
}
private fun isZero(d: Double): Boolean = d > -EPSILON && d < EPSILON

@JvmStatic
public fun multiplyInto(out: DoubleArray, a: DoubleArray, b: DoubleArray) {
Expand Down Expand Up @@ -92,17 +87,16 @@ public object MatrixMathHelper {
val translation = ctx.translation
val rotationDegrees = ctx.rotationDegrees

// create normalized, 2d array matrix
// and normalized 1d array perspectiveMatrix with redefined 4th column
if (isZero(transformMatrix[15])) {
return
}
val matrix = Array(4) { DoubleArray(4) }

val normalizedMatrix = DoubleArray(16)
val perspectiveMatrix = DoubleArray(16)
for (i in 0..3) {
for (j in 0..3) {
val value = transformMatrix[i * 4 + j] / transformMatrix[15]
matrix[i][j] = value
normalizedMatrix[i * 4 + j] = value
perspectiveMatrix[i * 4 + j] = if (j == 3) 0.0 else value
}
}
Expand All @@ -114,10 +108,19 @@ public object MatrixMathHelper {
}

// isolate perspective
if (!isZero(matrix[0][3]) || !isZero(matrix[1][3]) || !isZero(matrix[2][3])) {
if (
!isZero(normalizedMatrix[3]) ||
!isZero(normalizedMatrix[7]) ||
!isZero(normalizedMatrix[11])
) {
// rightHandSide is the right hand side of the equation.
// rightHandSide is a vector, or point in 3d space relative to the origin.
val rightHandSide = doubleArrayOf(matrix[0][3], matrix[1][3], matrix[2][3], matrix[3][3])
val rightHandSide = doubleArrayOf(
normalizedMatrix[3],
normalizedMatrix[7],
normalizedMatrix[11],
normalizedMatrix[15],
)

// Solve the equation by inverting perspectiveMatrix and multiplying
// rightHandSide by the inverse.
Expand All @@ -126,50 +129,51 @@ public object MatrixMathHelper {
multiplyVectorByMatrix(rightHandSide, transposedInversePerspectiveMatrix, perspective)
} else {
// no perspective
perspective[0] = 0.0
perspective[1] = 0.0
perspective[2] = 0.0
perspective[1] = perspective[2]
perspective[0] = perspective[1]
perspective[3] = 1.0
}

// translation is simple
for (i in 0..2) {
translation[i] = matrix[3][i]
}
translation[0] = normalizedMatrix[12]
translation[1] = normalizedMatrix[13]
translation[2] = normalizedMatrix[14]

// Now get scale and shear.
// 'row' is a 3 element array of 3 component vectors
val row = Array(3) { DoubleArray(3) }
for (i in 0..2) {
row[i][0] = matrix[i][0]
row[i][1] = matrix[i][1]
row[i][2] = matrix[i][2]
row[i][0] = normalizedMatrix[i * 4]
row[i][1] = normalizedMatrix[i * 4 + 1]
row[i][2] = normalizedMatrix[i * 4 + 2]
}

// Compute X scale factor and normalize first row.
scale[0] = v3Length(row[0])
row[0] = v3Normalize(row[0], scale[0])
v3NormalizeInPlace(row[0], scale[0])

// Compute XY shear factor and make 2nd row orthogonal to 1st.
skew[0] = v3Dot(row[0], row[1])
row[1] = v3Combine(row[1], row[0], 1.0, -skew[0])
v3CombineInPlace(row[1], row[0], 1.0, -skew[0])

// Now, compute Y scale and normalize 2nd row.
scale[1] = v3Length(row[1])
row[1] = v3Normalize(row[1], scale[1])
skew[0] /= scale[1]
val scaleY = v3Length(row[1])
scale[1] = scaleY
v3NormalizeInPlace(row[1], scaleY)
skew[0] /= scaleY

// Compute XZ and YZ shears, orthogonalize 3rd row
skew[1] = v3Dot(row[0], row[2])
row[2] = v3Combine(row[2], row[0], 1.0, -skew[1])
v3CombineInPlace(row[2], row[0], 1.0, -skew[1])
skew[2] = v3Dot(row[1], row[2])
row[2] = v3Combine(row[2], row[1], 1.0, -skew[2])
v3CombineInPlace(row[2], row[1], 1.0, -skew[2])

// Next, get Z scale and normalize 3rd row.
scale[2] = v3Length(row[2])
row[2] = v3Normalize(row[2], scale[2])
skew[1] /= scale[2]
skew[2] /= scale[2]
val scaleZ = v3Length(row[2])
scale[2] = scaleZ
v3NormalizeInPlace(row[2], scaleZ)
skew[1] /= scaleZ
skew[2] /= scaleZ

// At this point, the matrix (in rows) is orthonormal.
// Check for a coordinate system flip. If the determinant
Expand Down Expand Up @@ -340,6 +344,13 @@ public object MatrixMathHelper {
return doubleArrayOf(vector[0] * im, vector[1] * im, vector[2] * im)
}

private fun v3NormalizeInPlace(vector: DoubleArray, norm: Double) {
val inverseMagnitude = 1.0 / norm
vector[0] *= inverseMagnitude
vector[1] *= inverseMagnitude
vector[2] *= inverseMagnitude
}

/**
* The dot product of a and b, two 3-element vectors. From:
* https://code.google.com/p/webgl-mjs/source/browse/mjs.js
Expand Down Expand Up @@ -367,6 +378,17 @@ public object MatrixMathHelper {
)
}

private fun v3CombineInPlace(
a: DoubleArray,
b: DoubleArray,
aScale: Double,
bScale: Double,
) {
a[0] = aScale * a[0] + bScale * b[0]
a[1] = aScale * a[1] + bScale * b[1]
a[2] = aScale * a[2] + bScale * b[2]
}

/**
* From:
* http://www.opensource.apple.com/source/WebCore/WebCore-514/platform/graphics/transforms/TransformationMatrix.cpp
Expand Down
33 changes: 33 additions & 0 deletions ...ct-native/ReactAndroid/src/test/java/com/facebook/react/uimanager/MatrixMathHelperTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,39 @@ class MatrixMathHelperTest {
verifyZRotatedMatrix(42.55555555555, 0.0, 0.0, 42.556)
}

@Test
fun testDecomposingTranslationAndScale() {
val ctx = MatrixDecompositionContext()

MatrixMathHelper.decomposeMatrix(
doubleArrayOf(
2.0,
0.0,
0.0,
0.0,
0.0,
3.0,
0.0,
0.0,
0.0,
0.0,
4.0,
0.0,
5.0,
6.0,
7.0,
1.0,
),
ctx,
)

assertThat(ctx.perspective).containsExactly(0.0, 0.0, 0.0, 1.0)
assertThat(ctx.scale).containsExactly(2.0, 3.0, 4.0)
assertThat(ctx.skew).containsExactly(0.0, 0.0, 0.0)
assertThat(ctx.translation).containsExactly(5.0, 6.0, 7.0)
assertThat(ctx.rotationDegrees).containsExactly(0.0, 0.0, 0.0)
}

@Test
fun testDecomposing4x4MatrixToProduceAccurateYaxisAngles() {
val angles = doubleArrayOf(30.0, 45.0, 60.0, 75.0, 90.0)
Expand Down
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