test

//============================================================================
// Name        : test1.cpp
// Author      : 
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <math.h>
using namespace std;

void minusVector(float* result, float* a, float* b) {

	result[0] = a[0] - b[0];
	result[1] = a[1] - b[1];
	result[2] = a[2] - b[2];

}

void inputVector(float* v) {
	for (int x = 0; x < 3; x++) {
		cin >> v[x];
	}
}

void displayVector(float* v) {
	for (int x = 0; x < 3; x++) {
		cout << v[x] << ",";
	}
	cout << endl;
}

float dot(float* a, float* b) {
	return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}

float lengthVector(float* v) {
	return sqrt(dot(v, v));
}

void surfaceNormal(float* normal, float* p1, float* p2, float* p3) {

	float u[3];
	float v[3];
	minusVector(u, p2, p1);
	minusVector(v, p3, p1);

	displayVector(u);
	displayVector(v);

	normal[0] = u[1] * v[2] - u[2] * v[1];
	normal[1] = u[2] * v[0] - u[0] * v[2];
	normal[2] = u[0] * v[1] - u[1] * v[0];

}

void normalize(float* v) {

	float length = lengthVector(v);
	v[0] = v[0] / length;
	v[1] = v[1] / length;
	v[2] = v[2] / length;

}

int main() {

	// 3 points from std normal
	float p1[3]={0,0,1};
	float p2[3]={1,0,0};
	float p3[3]={0,1,0};

	//inputVector(p1);
	//inputVector(p2);
	//inputVector(p3);

	float normalFromInfinity[3];

	surfaceNormal(normalFromInfinity, p1, p2, p3);
	displayVector(normalFromInfinity);

	normalize(normalFromInfinity);
	displayVector(normalFromInfinity);

	float normalFromOrigin[3];

	surfaceNormal(normalFromOrigin, p1, p3, p2);
	displayVector(normalFromOrigin);

	normalize(normalFromOrigin);
	displayVector(normalFromOrigin);
	/*
	1,0,-1,
	0,1,-1,
	1,1,1,
	0.57735,0.57735,0.57735,
	0,1,-1,
	1,0,-1,
	-1,-1,-1,
	-0.57735,-0.57735,-0.57735,
	*/
	return 0;
}