Adds rotate vector function #6145
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This would make more sense in CBA. Also name of the function does not imply it is rotating around another vector, there is already |
| _normalVector params ["_ux", "_uy", "_uz"]; | ||
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| private _rotationMatrix = [ | ||
| [cos(_theta) + ((_ux^2) * (1 - cos(_theta))), (_ux * _uy * (1-cos(_theta))) - (_uz * sin(_theta)), (_ux * _uz * (1 - cos(_theta))) + (_uy * sin (_theta))], |
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You are doing cos(_theta) and sin(_theta) a lot in here. Saving it into a variable and reusing it would be alot more efficient.
| private _vyp = (_vx * ((_rotationMatrix select 1) select 0)) + (_vy * ((_rotationMatrix select 1) select 1)) + (_vz * ((_rotationMatrix select 1) select 2)); | ||
| private _vzp = (_vz * ((_rotationMatrix select 2) select 0)) + (_vy * ((_rotationMatrix select 2) select 1)) + (_vz * ((_rotationMatrix select 2) select 2)); | ||
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| private _returnVector = [_vxp, _vyp, _vzp]; |
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Cleaning up the code doesn't change the fact that this should go into CBA instead of ACE. |
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| private _vxp = (_vx * ((_rotationMatrix select 0) select 0)) + (_vy * ((_rotationMatrix select 0) select 1)) + (_vz * ((_rotationMatrix select 0) select 2)); | ||
| private _vyp = (_vx * ((_rotationMatrix select 1) select 0)) + (_vy * ((_rotationMatrix select 1) select 1)) + (_vz * ((_rotationMatrix select 1) select 2)); | ||
| private _vzp = (_vz * ((_rotationMatrix select 2) select 0)) + (_vy * ((_rotationMatrix select 2) select 1)) + (_vz * ((_rotationMatrix select 2) select 2)); |
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This could be written as:
private _vxp = _vector1 vectorDotProduct (_rotationMatrix select 0);
private _vyp = _vector1 vectorDotProduct (_rotationMatrix select 1);
private _vzp = _vector1 vectorDotProduct (_rotationMatrix select 2);
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I think we should use the Rodrigues Formula, when we translate this into CBA: |
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Remind me if it is mathematically legal to change the order between product and scalar multiplication: (_k vectorMultiply (_k vectorDotProduct _v) vectorMultiply (1 - cos(_theta)))-> (_k vectorMultiply ((_k vectorDotProduct _v) * (1 - cos _theta)))Because that could be slightly faster. |
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Here is what I mean: 6 multiplications 4 multiplications |
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Yes, you can do it like that. |
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Review ready. Whether it belongs in CBA or not is irrelevant. I'd rather know that we have it and where it is. |
When merged this pull request will:
Add a common function to rotate a vector by a given angle using a second vector as an axis of rotation.