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Simulate skew on Android #42676

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piaskowyk wants to merge 4 commits into from
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Simulate skew on Android #42676

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e52cd09
Fix skew on Android
piaskowyk Jan 25, 2024
9550464
Merge branch 'main' into @piaskowyk/fix-skew-on-android
piaskowyk May 28, 2024
2ca3110
Move from .java -> .kt
piaskowyk May 28, 2024
80b2397
Use Double
piaskowyk May 28, 2024
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36 changes: 34 additions & 2 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 @@ -437,12 +437,44 @@ public object MatrixMathHelper {

@JvmStatic
public fun applySkewX(m: DoubleArray, radians: Double) {
m[4] = Math.tan(radians)
val helperMatrix = DoubleArray(16);
resetIdentityMatrix(helperMatrix);
val skew = radians;
val rotationY = MatrixMathHelper.degreesToRadians(45.0);
val rotationX = Math.atan(1 / Math.sin(rotationY) * Math.tan(skew));
val scaleX = 1 / Math.cos(rotationY);
val scaleY = 1 / Math.cos(rotationX);

applyRotateY(m, rotationY);
applyRotateX(helperMatrix, rotationX);
multiplyInto(m, m, helperMatrix);

resetIdentityMatrix(helperMatrix);
applyScaleX(helperMatrix, scaleX);
applyScaleY(helperMatrix, scaleY);
applyPerspective(helperMatrix, 100000.0);
multiplyInto(m, m, helperMatrix);
}

@JvmStatic
public fun applySkewY(m: DoubleArray, radians: Double) {
m[1] = Math.tan(radians)
val helperMatrix = DoubleArray(16);
resetIdentityMatrix(helperMatrix);
val skew = radians;
val rotationX = MatrixMathHelper.degreesToRadians(45.0);
val rotationY = Math.atan(1 / Math.sin(rotationX) * Math.tan(skew));
val scaleX = 1 / Math.cos(rotationY);
val scaleY = 1 / Math.cos(rotationX);

applyRotateX(m, rotationX);
applyRotateY(helperMatrix, rotationY);
multiplyInto(m, m, helperMatrix);

resetIdentityMatrix(helperMatrix);
applyScaleX(helperMatrix, scaleX);
applyScaleY(helperMatrix, scaleY);
applyPerspective(helperMatrix, 100000.0);
multiplyInto(m, m, helperMatrix);
}

@JvmStatic
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