3D-Program-with-D3D/MathHelper.cpp at master · floatyears/3D-Program-with-D3D · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
#include "MathHelper.h"
#include <float.h>
#include <cmath>

const float MathHelper::Infinity = FLT_MAX;
const float MathHelper::Pi = 3.1415926535f;

float MathHelper::AngleFromXY(float x, float y)
{
	float theta = 0.0f;

	if(x >= 0.0f)
	{
		theta = atanf(y/x);
		if(theta < 0.0f)
			theta += 2.0f*Pi;
	}
	else
	{
		theta = atanf(y/x) + Pi;
	}

	return theta;
}

XMVECTOR MathHelper::RandUnitVec3()
{
	XMVECTOR One = XMVectorSet(1.0f,1.0f,1.0f,1.0f);
	XMVECTOR Zero = XMVectorZero();

	while (true)
	{
		XMVECTOR v = XMVectorSet(MathHelper::RandF(-1.0f,1.0f),MathHelper::RandF(-1.0f,1.0f),MathHelper::RandF(-1.0f,1.0f),0.0f);
		if(XMVector3Greater(XMVector3LengthSq(v),One))
			continue;
		return XMVector3Normalize(v);
	}
}

XMVECTOR MathHelper::RandHemisphereUnitVec3(XMVECTOR n)
{
	XMVECTOR One = XMVectorSet(1.0f,1.0f,1.0f,1.0f);
	XMVECTOR Zero = XMVectorZero();

	while (true)
	{
		XMVECTOR v = XMVectorSet(MathHelper::RandF(-1.0f,1.0f),MathHelper::RandF(-1.0f,1.0f),MathHelper::RandF(-1.0f,1.0f),0.0f);

		if(XMVector3Greater(XMVector3LengthSq(v),One))
			continue;
		if(XMVector3Less(XMVector3Dot(n,v),Zero))
			continue;

		return XMVector3Normalize(v);
	}
}