int main()
{
scanf("%d", &N);
GenerateConvexPolygon(N);
return 0;
}
int ConvexPolygonClipping(const MeshPolygon* clippedPolygon,
const MeshPolygon* clippingWindow,
Queue* queue)
{
if(NULL == clippedPolygon || NULL == clippingWindow || NULL == queue)
{
return WRONG_PARAM;
}
int allPointCountForClipping = 0;
const Point* pointListForClipingWindow = GetPolygonPointList(clippingWindow);
const int pointCountForClippingWindow = GetPolygonPointCount(clippingWindow);
allPointCountForClipping += pointCountForClippingWindow;
int clipingWindowPointInClippedWindowCount[3] = {0};
for (int i = 0; i < pointCountForClippingWindow; ++i)
{
int checkResult = PointInPolygon(clippedPolygon, pointListForClipingWindow[i].x, pointListForClipingWindow[i].z);
++clipingWindowPointInClippedWindowCount[checkResult + 1];
}
//裁剪多边形的顶点都位于被裁剪多边形的内部或者边上
//目前无法裁剪这种情况
if (0 == clipingWindowPointInClippedWindowCount[0])
{
return CLIPPING_WINDOW_ALL_IN_CLIPPED_POLYGON;
}
const Point* pointListForClippedPolygon = GetPolygonPointList(clippedPolygon);
const int pointCountForClippedPolygon = GetPolygonPointCount(clippedPolygon);
int clippedPolygonointInClippedWindowCount[3] = {0};
for (int i = 0; i < pointCountForClippedPolygon; ++i)
{
int checkResult = PointInPolygon(clippingWindow, pointListForClippedPolygon[i].x, pointListForClippedPolygon[i].z);
++clippedPolygonointInClippedWindowCount[checkResult + 1];
}
allPointCountForClipping += pointCountForClippedPolygon;
//被裁剪的多边形的顶点全部为与裁剪多边形内或边上
//不需要参见
if (0 == clippedPolygonointInClippedWindowCount[0])
{
return ALL_POINT_IN_CLIPPING_WINDOW;
}
//两多边形不相交 不需要裁剪
if (0 == clipingWindowPointInClippedWindowCount[2] && 0 == clippedPolygonointInClippedWindowCount[2])
{
return NOT_NEED_CLIPPING;
}
ClippingInterPoint* pointChainForClippingWindow = CreateClippingWindowData(clippedPolygon, clippingWindow);
ClippingInterPoint* pointChainForClippedPolygon = CreateClippedPolygonData(clippedPolygon, clippingWindow);
//查找交点并将交点插入正确的位置
const Vector* const pNormalOfClippedPolygon = GetPolygonNormal(clippedPolygon);
Rect checkRect;
for (int indexOfClippingWindow = 0; indexOfClippingWindow < pointCountForClippingWindow; ++indexOfClippingWindow)
{
int nextIndexOfClippingWindow = indexOfClippingWindow + 1 == pointCountForClippingWindow ? 0 : indexOfClippingWindow + 1;
for (int indexOfclippedPolygon = 0; indexOfclippedPolygon < pointCountForClippedPolygon; ++indexOfclippedPolygon)
{
int nextIndexOfClippedPolygon = indexOfclippedPolygon + 1 == pointCountForClippedPolygon ? 0 : indexOfclippedPolygon + 1;
ClippingInterPoint* const pBeginPointOfClippinWindow = &pointChainForClippingWindow[indexOfClippingWindow];
ClippingInterPoint* const pEndPointOfClippinWindow = &pointChainForClippingWindow[nextIndexOfClippingWindow];
ClippingInterPoint* const pBeginPointOfClippedPolygon = &pointChainForClippedPolygon[indexOfclippedPolygon];
ClippingInterPoint* const pEndPointOfClippedPolygon = &pointChainForClippedPolygon[nextIndexOfClippedPolygon];
Vector toBeginPoint = {pBeginPointOfClippinWindow->point.x - pBeginPointOfClippedPolygon->point.x,
0.0f,
pBeginPointOfClippinWindow->point.z - pBeginPointOfClippedPolygon->point.z};
Vector toEndPoint = {pEndPointOfClippinWindow->point.x - pBeginPointOfClippedPolygon->point.x,
0.0f,
pEndPointOfClippinWindow->point.z - pBeginPointOfClippedPolygon->point.z};
float cosofToBeginPoint = VectorDotProduct(&toBeginPoint, &pNormalOfClippedPolygon[indexOfclippedPolygon]);
float cosofToEndPoint = VectorDotProduct(&toEndPoint, &pNormalOfClippedPolygon[indexOfclippedPolygon]);
bool beginPointIsSpecial = (FloatEqualZero(cosofToBeginPoint) && cosofToEndPoint > 0.0f);
bool endPointIsSpecial = (FloatEqualZero(cosofToEndPoint) && cosofToBeginPoint> 0.0f);
if (beginPointIsSpecial || endPointIsSpecial)
{
//特殊点，即交点在被裁减的多边形的边上，且同在内侧
ClippingInterPoint* pTempPoint = beginPointIsSpecial ? pBeginPointOfClippinWindow : pEndPointOfClippinWindow;
pTempPoint->pointType = INTER_POINT_TYPE_CLIPPING_WINDOW_POINT_AN_INSERCTION_POINT;
ClippingInterPoint* pCurrentPositon = &pointChainForClippedPolygon[indexOfclippedPolygon];
ClippingInterPoint* pNextPosition = pCurrentPositon->next2ClippedPolygon;
ClippingInterPoint* pEndPosition = &pointChainForClippedPolygon[nextIndexOfClippedPolygon];
pTempPoint->tValueForClippedPolygon = GetTValue(&pBeginPointOfClippedPolygon->point, &pEndPointOfClippedPolygon->point, &pTempPoint->point);
while (true)
{
if( pTempPoint->tValueForClippedPolygon < pCurrentPositon->tValueForClippedPolygon)
{
ClippingInterPoint* pLastPosition = pCurrentPositon->prev2ClippedPolygon;
pLastPosition->next2ClippedPolygon = pTempPoint;
pCurrentPositon->prev2ClippedPolygon = pTempPoint;
pTempPoint->prev2ClippedPolygon = pLastPosition;
pTempPoint->next2ClippedPolygon = pCurrentPositon;
break;
}
else if (pEndPosition == pNextPosition)
{
pCurrentPositon->next2ClippedPolygon = pTempPoint;
pNextPosition->prev2ClippedPolygon = pTempPoint;
pTempPoint->prev2ClippedPolygon = pCurrentPositon;
pTempPoint->next2ClippedPolygon = pNextPosition;
break;
}
pCurrentPositon = pNextPosition;
pNextPosition = pCurrentPositon->next2ClippedPolygon;
}
continue;
}
if (FloatEqualZero(cosofToBeginPoint) && cosofToEndPoint < 0.0f)
{
//特殊点，即交点在被裁减的多边形的边上，且同在外侧
//直接抛弃，不处理
continue;
}
if (FloatEqualZero(cosofToEndPoint) && cosofToBeginPoint < 0.0f)
{
//特殊点，即交点在被裁减的多边形的边上，且同在外侧
//直接抛弃，不处理
continue;
}
//如果两点在边的同一侧，即没有交点，直接跳过
if (cosofToBeginPoint > 0.0f && cosofToEndPoint > 0.0f)
{
continue;
}
if (cosofToBeginPoint < 0.0f && cosofToEndPoint < 0.0f)
{
continue;
}
//如果有交点，则求交点并将交点插入正确的位置
//两相交线段求交点
//从而可以求出p的坐标 具体算法可以参考图形学算法
float tValue =cosofToBeginPoint;
tValue /= (cosofToBeginPoint - cosofToEndPoint);
float insertionX = pBeginPointOfClippinWindow->point.x + tValue * (pEndPointOfClippinWindow->point.x - pBeginPointOfClippinWindow->point.x);
float insertionZ = pBeginPointOfClippinWindow->point.z + tValue * (pEndPointOfClippinWindow->point.z - pBeginPointOfClippinWindow->point.z);
//检查点是否在线段的延长线上
Point point = {insertionX, insertionZ};
Point a = pBeginPointOfClippedPolygon->point;
Point b = pEndPointOfClippedPolygon->point;
MakeRectByPoint(&checkRect, &a, &b);
if(true != InRect(&checkRect, &point))
{
continue;
}
a = pBeginPointOfClippinWindow->point;
b = pEndPointOfClippinWindow->point;
MakeRectByPoint(&checkRect, &a, &b);
if(true != InRect(&checkRect, &point))
{
continue;
}
ClippingInterPoint* pTempPoint = (ClippingInterPoint*)malloc(sizeof(ClippingInterPoint));
++allPointCountForClipping;
pTempPoint->point = point;
pTempPoint->tValueForClippingWindow = tValue;
pTempPoint->tValueForClippedPolygon = GetTValue(&pBeginPointOfClippedPolygon->point, &pEndPointOfClippedPolygon->point, &point);
//通过遍历链表查找正确的位置插入生成点
ClippingInterPoint* pCurrentPositon = &pointChainForClippingWindow[indexOfClippingWindow];
ClippingInterPoint* pNextPosition = pCurrentPositon->next2ClippingdWindow;
ClippingInterPoint* pEndPosition = &pointChainForClippingWindow[nextIndexOfClippingWindow];
bool pointIsAdd = false;
while(true)
{
if (IsSamePoint(&pTempPoint->point, &pCurrentPositon->point))
{
//检查该点以否已经添加,如果已经添加则退出循环
//防止重复添加导致在后面在裁剪的时候死循环
pointIsAdd = true;
break;
}
if( pTempPoint->tValueForClippingWindow < pCurrentPositon->tValueForClippingWindow)
{
ClippingInterPoint* pLastPosition = pCurrentPositon->prev2ClippingdWindow;
pLastPosition->next2ClippingdWindow = pTempPoint;
pCurrentPositon->prev2ClippingdWindow = pTempPoint;
pTempPoint->prev2ClippingdWindow = pLastPosition;
pTempPoint->next2ClippingdWindow = pCurrentPositon;
break;
}
else if (pEndPosition == pNextPosition)
{
pCurrentPositon->next2ClippingdWindow = pTempPoint;
pNextPosition->prev2ClippingdWindow = pTempPoint;
pTempPoint->prev2ClippingdWindow = pCurrentPositon;
pTempPoint->next2ClippingdWindow = pNextPosition;
break;
}
pCurrentPositon = pNextPosition;
pNextPosition = pCurrentPositon->next2ClippingdWindow;
}
if (true == pointIsAdd)
{
free(pTempPoint);
continue;
}
//通过遍历链表查找正确的位置插入生成点
pCurrentPositon = &pointChainForClippedPolygon[indexOfclippedPolygon];
pNextPosition = pCurrentPositon->next2ClippedPolygon;
pEndPosition = &pointChainForClippedPolygon[nextIndexOfClippedPolygon];
while (true)
{
if( pTempPoint->tValueForClippedPolygon < pCurrentPositon->tValueForClippedPolygon)
{
ClippingInterPoint* pLastPosition = pCurrentPositon->prev2ClippedPolygon;
pLastPosition->next2ClippedPolygon = pTempPoint;
pCurrentPositon->prev2ClippedPolygon = pTempPoint;
pTempPoint->prev2ClippedPolygon = pLastPosition;
pTempPoint->next2ClippedPolygon = pCurrentPositon;
break;
}
else if (pEndPosition == pNextPosition)
{
pCurrentPositon->next2ClippedPolygon = pTempPoint;
pNextPosition->prev2ClippedPolygon = pTempPoint;
pTempPoint->prev2ClippedPolygon = pCurrentPositon;
pTempPoint->next2ClippedPolygon = pNextPosition;
break;
}
pCurrentPositon = pNextPosition;
pNextPosition = pCurrentPositon->next2ClippedPolygon;
}
if (cosofToBeginPoint < 0.0f && cosofToEndPoint > 0.0f)
{
pTempPoint->pointType = INTER_POINT_TYPE_INTERSECTION_POINT_FOR_IN;
}
else if(cosofToBeginPoint > 0.0f && cosofToEndPoint < 0.0f)
{
pTempPoint->pointType = INTER_POINT_TYPE_INTERSECTION_POINT_FOR_OUT;
}
else
{
assert(0);
}
}
}
//完成链表构建
//开始生成convex polygon
//首先检查是否有足够的空间容纳结果
int* bufferForPolygonConverCount = (int*)malloc(sizeof(int*) * allPointCountForClipping);
GenerateConvexPolygon(pointChainForClippedPolygon, pointCountForClippedPolygon, NULL, bufferForPolygonConverCount, allPointCountForClipping);
//完成链表构建
//开始生成convex polygon
for (int i = 0; i < pointCountForClippedPolygon; ++i)
{
pointChainForClippedPolygon[i].state = PROCESS_STATE_UNPROCESSED;
int checkResult = PointInPolygon(clippingWindow, pointChainForClippedPolygon[i].point.x, pointChainForClippedPolygon[i].point.z);
if (checkResult >= 0)
{
pointChainForClippedPolygon[i].state = PROCESS_STATE_NO_NEED_PROCESS;
}
}
GenerateConvexPolygon(pointChainForClippedPolygon, pointCountForClippedPolygon, queue, bufferForPolygonConverCount, allPointCountForClipping);
//释放分配的内存
ClippingInterPoint* pCurrent = &pointChainForClippedPolygon[0];
ClippingInterPoint* pNext = pCurrent->next2ClippedPolygon;
while (pNext != &pointChainForClippedPolygon[0])
{
if (INTER_POINT_TYPE_INTERSECTION_POINT_FOR_IN == pNext->pointType || INTER_POINT_TYPE_INTERSECTION_POINT_FOR_OUT == pNext->pointType)
{
pCurrent = pNext;
pNext = pNext->next2ClippedPolygon;
free(pCurrent);
}
else
{
pNext = pNext->next2ClippedPolygon;
}
}
Queue* checkQueue = CreateQueue(GetDataCountFromQueue(queue));
while (MeshPolygon* checkPolygon = (MeshPolygon*)PopDataFromQueue(queue))
{
if (true != IsSamePolygon(checkPolygon, clippedPolygon))
{
PushDataToQueue(checkQueue, (void*)checkPolygon);
}
}
ShiftQueueData(queue, checkQueue);
ReleaseQueue(checkQueue);
free(bufferForPolygonConverCount);
free(pointChainForClippedPolygon);
free(pointChainForClippingWindow);
return 0;
}
