给出一个扫描线多边形填充算法的代码示例
时间: 2023-06-06 07:06:59 浏览: 67
以下是一个简单的扫描线多边形填充算法的代码示例:
```
struct Edge
{
int ymax;
float x, dx;
Edge* next;
};
void insertEdge(Edge* e, Edge** list)
{
Edge* prev = nullptr;
Edge* curr = *list;
while (curr && e->x > curr->x)
{
prev = curr;
curr = curr->next;
}
if (!prev)
*list = e;
else
prev->next = e;
e->next = curr;
}
void removeEdge(Edge* e, Edge** list)
{
Edge* prev = nullptr;
Edge* curr = *list;
while (curr && curr != e)
{
prev = curr;
curr = curr->next;
}
if (!curr)
return;
if (!prev)
*list = curr->next;
else
prev->next = curr->next;
}
void fillPolygon(int* points, int numPoints, int color)
{
Edge* edges = nullptr;
int ymin = INT_MAX;
int ymax = INT_MIN;
// Initialize edges list
for (int i = 0; i < numPoints; i++)
{
int x1 = points[i * 2];
int y1 = points[i * 2 + 1];
int x2, y2;
if (i == numPoints - 1)
{
x2 = points[0];
y2 = points[1];
}
else
{
x2 = points[(i + 1) * 2];
y2 = points[(i + 1) * 2 + 1];
}
if (y1 == y2) // Horizontal line, skip
continue;
Edge* e = new Edge();
if (y1 > y2)
{
std::swap(x1, x2);
std::swap(y1, y2);
}
e->ymax = y2;
e->x = (float)x1;
e->dx = (float)(x2 - x1) / (float)(y2 - y1);
insertEdge(e, &edges);
ymin = std::min(ymin, y1);
ymax = std::max(ymax, y2);
}
// Scanline algorithm
for (int y = ymin; y <= ymax; y++)
{
Edge* curr = edges;
while (curr && curr->ymax < y)
{
removeEdge(curr, &edges);
curr = curr->next;
}
curr = edges;
while (curr)
{
if (curr->ymax >= y && curr->x <= curr->dx * (float)(y - curr->ymax) + curr->x)
{
int x = (int)curr->x;
drawPixel(x, y, color);
}
curr->x += curr->dx;
curr = curr->next;
}
}
// Cleanup
while (edges)
{
Edge* tmp = edges;
edges = edges->next;
delete tmp;
}
}
```
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