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Started by dawoodr Aug 10, 2014 at 11:54 PM 1 replies 1.2k views

Original Post

Aug 10, 2014 at 11:54 PM

Hello!


	XMVECTOR gringo = { 1, 2, 3, 4 };

	float a = XMVectorGetY(gringo);
	cout << a << endl;
	XMVectorSetY(gringo, 40);
	a = XMVectorGetY(gringo);
	cout << a << endl;

The first output should be 2 which it is. The second output should be 40 put it's still 2, why? What have I done wrong?

Regards!

Buckeye

274

Buckeye

Aug 11, 2014 at 12:08 AM

What have I done wrong?

XMVectorSetY does not set the Y value in gringo. It returns an XMVECTOR the same as the argument (gringo, in your case), except the Y value is replaced. Your code generates the new vector, which would be { 1, 40, 3, 4} but you don't store it.


    XMVECTOR g = { 1, 2, 3, 4 };
    float a = XMVectorGetY(g); // get g's Y value of 2.0f
    XMVECTOR g2 = XMVectorSetY(g, 40.0f);
    a = XMVectorGetY(g2); // get g2's Y value of 40.0f

Alternatively,


gringo = XMVectorSetY(gringo, 40.0f);
a = XMVectorGetY(gringo); // now a==40.0f

FYI, I didn't know that of my own certain knowledge. I looked at the docs (which you can, also) and tried a quick test.

dawoodr

Author

dawoodr

Aug 11, 2014 at 12:18 AM

Thanks, so it was just that it was never stored,

Here is how I changed it now and it works fine, thanks once again!

XMVECTOR gringo = { 1, 2, 3, 4 };

float a = XMVectorGetY(gringo);

cout << a << endl;

gringo = XMVectorSetY(gringo, 40);

a = XMVectorGetY(gringo);

cout << a << endl;

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