results are different from the DirectX math library (DirectXMath.h)

[badasahog]

Hi!

I'm trying to find a C alternative to the DirectXMath.h header (which requires C++)

I'm brand new to this repo, so please excuse me if I'm missing something obvious, but it appears that DirectXMath.h gives different results from this library.

example:

int Width = 800;
int Height = 600;

XMMATRIX tmpMat = XMMatrixPerspectiveFovLH(
			45.0f * (3.14f / 180.0f),
			(float)Width / (float)Height,
			0.1f,
			1000.0f);
	
for (int i = 0; i < 4; i++)
{

	for(int j = 0; j < 4; j++)
		std::cout << tmpMat.r[i].m128_f32[j] << '\t' << '\t';
	std::cout << '\n';
}

std::cout << '\n';

mat4_perspective(
tmpMat.r[0].m128_f32,
45.0f * (3.14f / 180.0f),
(float)Width / (float)Height,
0.1f,
1000.0f);

for (int i = 0; i < 4; i++)
{

	for (int j = 0; j < 4; j++)
		std::cout << tmpMat.r[i].m128_f32[j] << '\t' << '\t';
	std::cout << '\n';
}
std::cout << '\n';

output:

1.81168 0 0 0
0 2.41557 0 0
0 0 1.0001 1
0 0 -0.10001 0

1.81168 0 0 0
0 0.41398 0 0
0 0 -1.0001 -1
0 0 -0.10001 0

[Rickodesea]

This is true. I am having the same experience comparing this library with the C++ GLM.
There seem to be minor differences in the calculations. I assume the one in MathC is incorrect and needs to be updated.