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#include <iostream>
#include <string>
#include <stdlib.h>
#include <vector>
#include <Eigen3/Dense>

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include <stb_image_write.h>

using namespace std;
using namespace Eigen;

string filePath;
int w, h, n;
const int points = 4;
vector<pair<int, int>> rectBefore;	// 变换前的四边形
vector<pair<int, int>> rectAfter;	// 变换后的矩形位置
Vector4d cX,cY;						// x,y对于的四个参数

void copyTo(unsigned char *src, int x0, int y0, unsigned char *des, int x1, int y1) {
	if ((x1 < 0 || x1 >= w) || (y1 < 0 || y1 >= h)) return; // 出界不考虑
	if ((x0 < 0 || x0 >= w) || (y0 < 0 || y0 >= h)) return; // 出界不考虑
	for (int i = 0; i < n; i++) {
		des[w*n*y1 + n * x1 + i] = src[w*n*y0 + n * x0 + i];
	}
}

pair<int,int> getPos(int x, int y) {
	int x1 = cX[0] * x + cX[1] * y + cX[2] * x*y + cX[3];
	int y1 = cY[0] * x + cY[1] * y + cY[2] * x*y + cY[3];
	return make_pair(x1, y1);
}

int main()
{
	cin >> filePath;
	unsigned char *data = stbi_load(filePath.c_str(), &w, &h, &n, 0);
	unsigned char *copy = NULL;
	if (data == NULL) {
		cout << stbi_failure_reason() << endl;
	}
	else {
		// 复制一份变换用
		copy = (unsigned char*)malloc(w*n*h);
		memset(copy, 0, w*n*h);
		// 获取变换前坐标
		for (int i = 0; i < points; i++) {
			int x, y; cin >> x >> y;
			rectBefore.push_back(make_pair(x, y));
		}
		// 获取变换后坐标，与上一一对应
		for (int i = 0; i < points; i++) {
			int x, y; cin >> x >> y;
			rectAfter.push_back(make_pair(x, y));
		}
		Matrix4d mid;	// 中间矩阵
		Vector4d resX, resY;	// 转换后的xy坐标
		for (int i = 0; i < 4; i++) {
			mid(i, 0) = rectBefore[i].first;
			mid(i, 1) = rectBefore[i].second;
			mid(i, 2) = rectBefore[i].first*rectBefore[i].second;
			mid(i, 3) = 1;
			resX(i) = rectAfter[i].first;
			resY(i) = rectAfter[i].second;
		}
		// 求解线性方程组
		cX = mid.lu().solve(resX);
		cY = mid.lu().solve(resY);
		// 开始转换
		for (int i = 0; i < w; i++) {
			for (int j = 0; j < h; j++) {
				pair<int, int> newPos = getPos(i, j);
				copyTo(data, newPos.first, newPos.second, copy, i, j);
			}
		}
		stbi_write_png("out.png", w, h, n, copy, 0);
		stbi_image_free(data);
		free(copy);
	}
	system("pause");
	return 0;
}