它再次出现在周末,这意味着我可以玩hobby project。
我已经厌倦了手工创建测试级别,所以我想我会从引擎开发中休息一下并在级别编辑器上工作:
Level Editor http://gfilter.net/junk/Editor.JPG
我想在编辑器中实现泛洪填充算法,就像在绘图程序中一样。有没有人能指出哪种技术对我有用?
该级别只是一个2d数组,因此可以认为它与位图相同。
谢谢!
答案 0 :(得分:8)
维基百科的文章相当不错。只要您的网格很小,几乎任何东西都可以工作。
今年秋天早些时候,我在1000万像素扫描图像上做了一些洪水填充。 (问题是要去除在复印机上扫描的书页的黑边。)在这种情况下,只有两种颜色,所以我基本上把问题看作是在无向图中搜索,每个像素连接到它的邻居四个指南针方向。我维护了一个单独的位图来跟踪访问过的像素。
主要调查结果是
请勿尝试递归深度优先搜索。你真的想要一个明确的数据结构。
辅助队列使用的空间比堆栈少得多。大约四十倍的空间。换句话说,更喜欢广度优先搜索到深度优先搜索。
同样,这些调查结果仅适用于具有多个百万像素的网格。在你问题中显示的一个漂亮的小网格上,任何简单的算法都应该有用。
答案 1 :(得分:6)
我们必须为学校编程:
1: stuff the start pixel into a queue, note its color. note it as added.
2: begin picking a pixel off the queue. If it's similar to the start pixel:
2: put all its neighbours into the queue
for each added pixel, note it's added. if already noted for a pixel, don't
add it anymore.
3: color it with the destination color.
3: nonempty => jump back to 2
4: empty => we are finished
根据我们是8邻居还是4邻居,我们检查所有8个邻居像素,或仅检查某个像素左/右或上/下的像素。这是代码(使用ImageJ。我删除了一些不相关的代码)。我希望它有意义,它是Java。只是提出问题:
public class Uebung1_2 implements PlugInFilter, MouseListener {
private ImageProcessor ip;
boolean[] state;
int[] pixels;
Queue<Integer> nextPixels;
int threshould;
/**
* adds one pixel to the next-pixel queue only if it's not
* already added.
*/
void addNextPixel(int p) {
if(!state[p]) {
nextPixels.add(p);
state[p] = true;
}
}
boolean pixelsSimilar(int color1, int color2) {
int dr = Math.abs(((color1 >> 16) & 0xff) -
((color2 >> 16) & 0xff));
int dg = Math.abs(((color1 >> 8) & 0xff) -
((color2 >> 8) & 0xff));
int db = Math.abs(((color1 >> 0) & 0xff) -
((color2 >> 0) & 0xff));
return ((double)(dr + dg + db) / 3.0) <= threshould;
}
/**
* actually does the hard work :)
* @param x the x position from which to start filling
* @param y the y position from which to start filling
*/
private void doFill(int x, int y, boolean connect8) {
// first, add the start pixel
int width = ip.getWidth(),
height = ip.getHeight();
/* for 8bit, we just gonna take the median of rgb */
Color colorC = ij.gui.Toolbar.getForegroundColor();
int color = colorC.getRGB();
int firstPixel = ip.get(x, y);
// go on with the mainloop
addNextPixel(y * width + x);
while(!nextPixels.isEmpty()) {
int nextPixel = nextPixels.remove();
int pixel = pixels[nextPixel];
if(pixelsSimilar(pixel, firstPixel)) {
// yay it matches. put the neighbours.
int xN = nextPixel % width,
yN = nextPixel / width;
/* the three pixels above */
if(yN - 1 >= 0) {
if(connect8) {
if(xN + 1 < width) {
addNextPixel(nextPixel - width + 1);
}
if(xN - 1 >= 0) {
addNextPixel(nextPixel - width - 1);
}
}
addNextPixel(nextPixel - width);
}
/* pixels left and right from the current one */
if(xN > 0) {
addNextPixel(nextPixel - 1);
}
if(xN + 1 < width) {
addNextPixel(nextPixel + 1);
}
/* three pixels below */
if(yN + 1 < height) {
if(connect8) {
if(xN + 1 < width) {
addNextPixel(nextPixel + width + 1);
}
if(xN - 1 >= 0) {
addNextPixel(nextPixel + width - 1);
}
}
addNextPixel(nextPixel + width);
}
/* color it finally */
pixels[nextPixel] = color;
}
}
}
@Override
public void run(ImageProcessor ip) {
ij.WindowManager.getCurrentImage().getCanvas().addMouseListener(this);
this.ip = ip;
this.pixels = (int[])ip.getPixels();
this.state = new boolean[ip.getPixelCount()];
this.nextPixels = new LinkedList<Integer>();
}
@Override
public int setup(String arg0, ImagePlus arg1) {
return DOES_RGB;
}
@Override
public void mouseClicked(MouseEvent e) {
ij.WindowManager.getCurrentWindow().getCanvas().removeMouseListener(this);
ij.gui.GenericDialog g = new GenericDialog("Please enter parameters");
g.addChoice("connection", new String[]{"4-connect", "8-connect"}, "8-connect");
g.addNumericField("Threshould (0..255)", 0.0, 3);
g.showDialog();
boolean connect8 = g.getNextChoice().equals("8-connect");
threshould = (int) g.getNextNumber();
doFill(e.getX(), e.getY(), connect8);
ij.WindowManager.getCurrentImage().draw();
}
}
答案 2 :(得分:5)
答案 3 :(得分:5)
Wikpedia在Flood fill文章中提供了一些不同洪水填充技术的伪代码示例。您选择哪种技术取决于应用程序。
请记住,洪水填充很容易被线程化(类似于快速排序)。
答案 4 :(得分:2)
公平地说,它应该很简单。因为你有基本的瓷砖结构,所以算法很简单:
Select Tile To Fill:
Fill Till
Check neighbouring Tiles - If Empty Then Fill
Repeat, for all filled tiles.
免责声明:以上是一个非常基本的描述。网上有很多参考资料,它比我能解释得好得多。
答案 5 :(得分:1)
简单的功能,无需检查色差
使用:
<div class="row">
<div class="col-sm-8" style="font-size: 24pt">
<a href="" onmouseenter="toggleShow('image1');" onmouseleave="toggleHide('image1');"> INSTITUT HENRI POINCARRE, POSTER — 2017</a>
</div>
<div class="col">
<img style="display:none;" id="image1" src="image/ihp_poster01.JPG" class="img-fluid" alt="Responsive image">
</div>
</div>
<div class="row">
<div class="col-sm-8" style="font-size: 24pt">
<a href="" onmouseenter="toggleShow('image2');" onmouseleave="toggleHide('image2');"> INSTITUT HENRI POINCARRE, POSTER — 2017</a>
</div>
<div class="col">
<img style="display:none;" id="image2" src="image/ihp_poster01.JPG" class="img-fluid" alt="Responsive image">
</div>
</div>
主要功能:
var img = Image.FromFile("test.png");
img = img.FloodFill(new Point(0, 0), Color.Red);
img.Save("testcomplete.png", ImageFormat.Png);
答案 6 :(得分:0)
这是在C#程序中如何使用GDI +例程的示例。
(https://www.pinvoke.net/default.aspx/gdi32.extfloodfill)
using System.Runtime.InteropServices;
//insert by Zswang(wjhu111#21cn.com) at 2007-05-22
[DllImport("gdi32.dll")]
public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);
[DllImport("gdi32.dll")]
public static extern IntPtr CreateSolidBrush(int crColor);
[DllImport("gdi32.dll")]
public static extern bool ExtFloodFill(IntPtr hdc, int nXStart, int nYStart,
int crColor, uint fuFillType);
[DllImport("gdi32.dll")]
public static extern bool DeleteObject(IntPtr hObject);
[DllImport("gdi32.dll")]
public static extern int GetPixel(IntPtr hdc, int x, int y);
public static uint FLOODFILLBORDER = 0;
public static uint FLOODFILLSURFACE = 1;
private void button1_Click(object sender, EventArgs e)
{
Graphics vGraphics = Graphics.FromHwnd(Handle);
vGraphics.DrawRectangle(Pens.Blue, new Rectangle(0, 0, 300, 300));
vGraphics.DrawRectangle(Pens.Blue, new Rectangle(50, 70, 300, 300));
IntPtr vDC = vGraphics.GetHdc();
IntPtr vBrush = CreateSolidBrush(ColorTranslator.ToWin32(Color.Red));
IntPtr vPreviouseBrush = SelectObject(vDC, vBrush);
ExtFloodFill(vDC, 10, 10, GetPixel(vDC, 10, 10), FLOODFILLSURFACE);
SelectObject(vDC, vPreviouseBrush);
DeleteObject(vBrush);
vGraphics.ReleaseHdc(vDC);
}
如果在OnPaint事件处理程序中调用此方法,则可以使用Graphics vGraphics = Graphics.FromHwnd(Handle);
而不是使用e.Graphics
。为我工作得很好。
有时最好不要重新发明算法并使用现有的例程,尽管在移植到Mono时可能会遇到一些问题。