diff --git a/NationalFlag/NationalFlag/Fill.cpp b/NationalFlag/NationalFlag/Fill.cpp
new file mode 100644
index 0000000..ce0a8b5
--- /dev/null
+++ b/NationalFlag/NationalFlag/Fill.cpp
@@ -0,0 +1,240 @@
+#include "pch.h"
+#include "Fill.h"
+#define Round(x) (int)(x + 0.5)
+
+CFill::CFill() {
+	PNum = 0;
+	P = NULL;
+	pEdge = NULL;
+	pHeadB = NULL;
+	pHeadE = NULL;
+}
+
+CFill::~CFill() {
+	if (P != NULL) {
+		delete[] P;
+		P = NULL;
+	}
+	ClearMemory();
+}
+
+void CFill::SetPoint(CPi2 *p, int m) {
+	P = new CPi2[m];
+	for (int i = 0; i < m; i++) {
+		P[i] = p[i];
+	}
+	PNum = m;
+}
+
+void CFill::CreateBucket() {
+	int yMin, yMax;
+	yMin = yMax = P[0].y;
+	for (int i = 0; i < PNum; i++) {
+		if (P[i].y < yMin) {
+			yMin = P[i].y;
+		}
+		if (P[i].y > yMax) {
+			yMax = P[i].y;
+		}
+	}
+	for (int y = yMin; y <= yMax; y++) {
+		if (yMin == y) {
+			pHeadB = new CBucket;
+			pCurrentB = pHeadB;
+			pCurrentB->ScanLine = yMin;
+			pCurrentB->pET = NULL;
+			pCurrentB->pNext = NULL;
+		}
+		else {
+			pCurrentB->pNext = new CBucket;
+			pCurrentB = pCurrentB->pNext;
+			pCurrentB->ScanLine = y;
+			pCurrentB->pET = NULL;
+			pCurrentB->pNext = NULL;
+		}
+	}
+}
+
+void CFill::CreateEdge() {
+	for (int i = 0; i < PNum; i++) {
+		pCurrentB = pHeadB;
+		int j = (i + 1) % PNum;
+		if (P[i].y < P[j].y) {
+			pEdge = new CAET;
+			pEdge->x = P[i].x;
+			pEdge->yMax = P[j].y;
+			pEdge->k = (P[j].x - P[i].x) / (P[j].y - P[i].y);
+			pEdge->ps = P[i];
+			pEdge->pe = P[j];
+			pEdge->pNext = NULL;
+			while (pCurrentB->ScanLine != P[i].y)
+				pCurrentB = pCurrentB->pNext;
+		}
+		if (P[j].y < P[i].y) {
+			pEdge = new CAET;
+			pEdge->x = P[j].x;
+			pEdge->yMax = P[i].y;
+			pEdge->k = (P[i].x - P[j].x) / (P[i].y - P[j].y);
+			pEdge->ps = P[i];
+			pEdge->pe = P[j];
+			pEdge->pNext = NULL;
+			while (pCurrentB->ScanLine != P[j].y)
+				pCurrentB = pCurrentB->pNext;
+		}
+		if (P[i].y != P[j].y) {
+			pCurrentE = pCurrentB->pET;
+			if (pCurrentE == NULL) {
+				pCurrentE = pEdge;
+				pCurrentB->pET = pCurrentE;
+			}
+			else {
+				while (pCurrentE->pNext != NULL)
+					pCurrentE = pCurrentE->pNext;
+				pCurrentE->pNext = pEdge;
+			}
+		}
+	}
+}
+
+void CFill::Gouraud(CDC *pDC) {
+	CAET *pT1 = NULL, *pT2 = NULL;
+	pHeadE = NULL;
+	for (pCurrentB = pHeadB; pCurrentB != NULL; pCurrentB = pCurrentB->pNext) {
+		for (pCurrentE = pCurrentB->pET; pCurrentE != NULL; pCurrentE = pCurrentE->pNext) {
+			pEdge = new CAET;
+			pEdge->x = pCurrentE->x;
+			pEdge->yMax = pCurrentE->yMax;
+			pEdge->k = pCurrentE->k;
+			pEdge->ps = pCurrentE->ps;
+			pEdge->pe = pCurrentE->pe;
+			pEdge->pNext = NULL;
+			AddET(pEdge);
+		}
+		ETOrder();
+		pT1 = pHeadE;
+		if (pT1 == NULL)
+			return;
+		while (pCurrentB->ScanLine >= pT1->yMax) {
+			CAET *pAETTEmp = pT1;
+			pT1 = pT1->pNext;
+			delete pAETTEmp;
+			pHeadE = pT1;
+			if (pHeadE == NULL)
+				return;
+		}
+		if (pT1->pNext != NULL) {
+			pT2 = pT1;
+			pT1 = pT2->pNext;
+		}
+		while (pT1 != NULL) {
+			if (pCurrentB->ScanLine >= pT1->yMax) {
+				CAET *pAETTemp = pT1;
+				pT2->pNext = pT1->pNext;
+				pT1 = pT2->pNext;
+				delete pAETTemp;
+			}
+			else {
+				pT2 = pT1;
+				pT1 = pT2->pNext;
+			}
+		}
+		BOOL bInFlag = FALSE;
+		double xb, xe;
+		CRGB cb, ce, c;
+		for (pT1 = pHeadE; pT1 != NULL; pT1 = pT1->pNext) {
+			if (FALSE == bInFlag) {
+				xb = pT1->x;
+				cb = LinearDifferential(pT1->ps.y, pCurrentB->ScanLine, pT1->pe.y, pT1->ps.c, pT1->pe.c);
+				bInFlag = TRUE;
+			}
+			else {
+				xe = pT1->x;
+				ce = LinearDifferential(pT1->ps.y, pCurrentB->ScanLine, pT1->pe.y, pT1->ps.c, pT1->pe.c);
+				for (double x = xb; x < xe; x++) {
+					c = LinearDifferential(xb, x, xe, cb, ce);
+					pDC->SetPixelV(Round(x), pCurrentB->ScanLine, RGB(c.red * 255, c.green * 255, c.blue * 255));
+				}
+				bInFlag = FALSE;
+			}
+		}
+		for (pT1 = pHeadE; pT1 != NULL; pT1 = pT1->pNext)
+			pT1->x = pT1->x + pT1->k;
+	}
+}
+
+void CFill::AddET(CAET *pNewEdge) {
+	CAET *pCE = pHeadE;
+	if (pCE == NULL) {
+		pHeadE = pNewEdge;
+		pCE = pHeadE;
+	}
+	else {
+		while (pCE->pNext != NULL) {
+			pCE = pCE->pNext;
+		}
+		pCE->pNext = pNewEdge;
+	}
+}
+
+void CFill::ETOrder() {
+	CAET *pT1, *pT2;
+	int Count = 1;
+	pT1 = pHeadE;
+	if (pT1 == NULL) {
+		return;
+	}
+	if (pT1->pNext == NULL) {
+		return;
+	}
+	while (pT1->pNext != NULL) {
+		Count++;
+		pT1 = pT1->pNext;
+	}
+	for (int i = 0; i < Count - 1; i++) {
+		CAET **pPre = &pHeadE;
+		pT1 = pHeadE;
+		for (int j = 0; j < Count - 1 - i; j++) {
+			pT2 = pT1->pNext;
+
+			if ((pT1->x > pT2->x) || ((pT1->x == pT2->x) && (pT1->k > pT2->k))) {
+				pT1->pNext = pT2->pNext;
+				pT2->pNext = pT1;
+				*pPre = pT2;
+				pPre = &(pT2->pNext);
+			}
+			else {
+				pPre = &(pT1->pNext);
+				pT1 = pT1->pNext;
+			}
+		}
+	}
+}
+
+void CFill::ClearMemory() {
+	DeleteAETChain(pHeadE);
+	CBucket *pBucket = pHeadB;
+	while (pBucket != NULL) {
+		CBucket *pBucketTemp = pBucket->pNext;
+		DeleteAETChain(pBucket->pET);
+		delete pBucket;
+		pBucket = pBucketTemp;
+	}
+	pHeadB = NULL;
+	pHeadE = NULL;
+}
+
+void CFill::DeleteAETChain(CAET *pAET) {
+	while (pAET != NULL) {
+		CAET *pAETTemp = pAET->pNext;
+		delete pAET;
+		pAET = pAETTemp;
+	}
+}
+
+CRGB CFill::LinearDifferential(double y0, double y, double y1, CRGB c0, CRGB c1) {
+	CRGB c;
+	double t;
+	t = (y - y0) / (y1 - y0);
+	c = (1 - t) * c0 + t * c1;
+	return c;
+}