So I am creating a game in java using awt library.
I have created Meteoroid which will fall from top.
Problem: problem is that Meteoroid x position overlap on some of the other meteroids.
is there math formula to do this?
Random r = new Random();
int maxX = WINDOW_WIDTH;
int minX = 0;
for (int i = 0; i < 100; i++) {
// (x, y, width, height)
Meteoroid m = new Meteoroid(r.nextInt(maxX - minX + 1) + minX, r.nextInt(10)+0, 40, 40);
}
set a value for x position and increment every time a picture is created.
Related
I want to calculate the big O of the following algorithms for resizing binary images:
Bilinear interpolation:
double scale_x = (double)new_height/(height-1);
double scale_y = (double)new_width/(width-1);
for (int i = 0; i < new_height; i++)
{
int ii = i / scale_x;
for (int j = 0; j < new_width; j++)
{
int jj = j / scale_y;
double v00 = matrix[ii][jj], v01 = matrix[ii][jj + 1],
v10 = matrix[ii + 1][jj], v11 = matrix[ii + 1][jj + 1];
double fi = i / scale_x - ii, fj = j / scale_y - jj;
double temp = (1 - fi) * ((1 - fj) * v00 + fj * v01) +
fi * ((1 - fj) * v10 + fj * v11);
if (temp >= 0.5)
result[i][j] = 1;
else
result[i][j] = 0;
}
}
Nearest neighbour interpolation
double scale_x = (double)height/new_height;
double scale_y = (double)width/new_width;
for (int i = 0; i < new_height; i++)
{
int srcx = floor(i * scale_x);
for (int j = 0; j < new_width; j++)
{
int srcy = floor(j * scale_y);
result[i][j] = matrix[srcx][srcy];
}
}
I assumed that the complexity of both of them is the loop dimensions, i.e O(new_height*new_width). However, the bilinear interpolation surely works much slower than the nearest neighbour. Could you please explain how to correctly compute complexity?
They are both running in Theta(new_height*new_width) time because except for the loop iterations all operations are constant time.
This doesn't in any way imply that the two programs will execute equally fast. It merely means that if you increase new_height and/or new_width to infinity, the ratio of execution time between the two programs will neither go to infinity nor to zero.
(This is making the assumption that the integer types are unbounded and that all arithmetic operations are constant time operations independent of the length of the operands. Otherwise there will be another relevant factor accounting for the cost of the arithmetic.)
I have an image that has been processed throw:
//UIImage to Mat
cv::Mat originalMat = [self cvMatFromUIImage:inputImage];
//Grayscale
cv::Mat grayMat;
cv::cvtColor(originalMat, grayMat, CV_RGB2GRAY);
//Blur
cv::Mat gaussMat;
cv::GaussianBlur( grayMat , gaussMat, cv::Size(9, 9), 2, 2 );
//Threshold
cv::threshold(grayMat,tMat,100,255,cv::THRESH_BINARY);
than I want to analyze (calculate qty of white and black points) that belows to line. For instance: I have an image 100x120px and I want to check lines where x = 5 and y = from 0 to 119; and vice versa x = 0..99; y = 5;
so I expect that Mat will contains x - Mat.cols and y - Mat.rows but looks it saves data in another way. for example I've tried to change pixels color that belows to lines but didn't get 2 lines:
for( int x = 0; x < tMat.cols; x++ ){
tMat.at<cv::Vec4b>(5,x)[0] = 100;
}
for( int y = 0; y < tMat.rows; y++ ){
tMat.at<cv::Vec4b>(y,5)[0] = 100;
}
return [self UIImageFromCVMat:tMat];
result for white image:
why I did't get 2 lines? Is it possible to draw\check lines in Mat directly? what if I going to check line that calculates via y = kx + b?
You are accessing the pixel values in the wrong way. You are working with image that only has one channel, that's why you should access pixel values like this:
for (int x = 0; x < tMat.cols; x++){
tMat.at<unsigned char>(5, x) = 100;
}
for (int y = 0; y < tMat.rows; y++){
tMat.at<unsigned char>(y, 5) = 100;
}
The Mat element's type is defined by two properties - the number of channels and the underlying type of data. If you do not know the meaning of those terms, I strongly suggest that you read the documentation for methods cv::Mat::type(), cv::Mat::channels() and cv::Mat::depth().
Two more examples:
mat.at<float>(x, y) = 1.0f; // if mat type is CV_32FC1
mat.at<cv::Vec3b>(x, y) = Vec3b(1, 2, 3); // if mat type is CV_8UC3
Probably an issue with your Mat data types. The output of threshold is a single channel image that is 8-bit or 32-bit (http://docs.opencv.org/2.4/modules/imgproc/doc/miscellaneous_transformations.html?highlight=threshold#threshold), so you probably should not be setting values with Mat.at<Vec4b>[0].
Here's a function to return the type of your matrix. Usage is in the commented out part. Copied from How to find out what type of a Mat object is with Mat::type() in OpenCV.
std::string type2str(int type){
//string ty = type2str( comparisonResult.type() );
//printf("Matrix: %s %dx%d \n", ty.c_str(), comparisonResult.cols, comparisonResult.rows );
string r;
uchar depth = type & CV_MAT_DEPTH_MASK;
uchar chans = 1 + (type >> CV_CN_SHIFT);
switch ( depth ) {
case CV_8U: r = "8U"; break;
case CV_8S: r = "8S"; break;
case CV_16U: r = "16U"; break;
case CV_16S: r = "16S"; break;
case CV_32S: r = "32S"; break;
case CV_32F: r = "32F"; break;
case CV_64F: r = "64F"; break;
default: r = "User"; break;
}
r += "C";
r += (chans+'0');
return r;}
So I have an image which contains a tile-sheet, where each tile is approx 16 pixels wide, and high. But there spaced out with a transparent spacer between each tile.
Like so:
But this is ugly, and makes displaying the sprites in the program annoying, not to mention it wastes valuable image space. Is there any easy (Besides me manually using Photoshop to move each individual tile) way to make it look like this?
I looked through Photoshop macros, as-well as other programs and I diden't seem to find anything that would directly do this.
Google also suggests I go to home-depo and get tile caulk remover.
Try this snippet. As you said, it assumes tiles are always going to be 16 pixels. Top left one is in the correct position and a single pixel gap. The script assumes the document will opened with the layer containing your tiles set as the active layer.
#target photoshop
app.preferences.rulerUnits = Units.PIXELS;
app.preferences.typeUnits = TypeUnits.PIXELS;
var gap = 1;
var tileSize = 16;
var doc = app.activeDocument.duplicate();
var sourceLyr = doc.activeLayer;
var xTilePosition = 0;
var yTilePosition = 0;
for (var x = 0; x < sourceLyr.bounds[2]; x = x+ tileSize + 1 ) {
for (var y = 0; y < sourceLyr.bounds[3]; y = y + tileSize + 1) {
if (x > 0 || y > 0) {
app.activeDocument = doc;
doc.activeLayer = sourceLyr;
selRegion = Array(Array(x, y),
Array(x + tileSize, y),
Array(x + tileSize, y + tileSize),
Array(x, y + tileSize),
Array(x, y))
doc.selection.select(selRegion);
var dx = x - (xTilePosition * tileSize);
var dy = y - (yTilePosition * tileSize);
doc.selection.translate(0 - dx, 0 - dy);
}
yTilePosition ++;
}
xTilePosition++;
yTilePosition = 0;
}
Convert point from coordinate system to java ,
in Java Frame
+-------x
|
|
|
y
I want it as this one
y
|
|
+------x
please help me
You can change it, let y = Ymax - y
public void paintControl(PaintEvent e) {
Canvas canvas = (Canvas) e.widget;
int maxX = canvas.getSize().x - 20;
int maxY = canvas.getSize().y - 20;
e.gc.setForeground(e.display.getSystemColor(SWT.COLOR_BLUE));
int h = 0;
int pixelCount = 4;
e.gc.drawLine(50, maxY, maxX, maxY);
e.gc.drawLine(50, maxY, 50, 0 + 20);
I have successfully implemented the mandelbrot set as described in the wikipedia article, but I do not know how to zoom into a specific section. This is the code I am using:
+(void)createSetWithWidth:(int)width Height:(int)height Thing:(void(^)(int, int, int, int))thing
{
for (int i = 0; i < height; ++i)
for (int j = 0; j < width; ++j)
{
double x0 = ((4.0f * (i - (height / 2))) / (height)) - 0.0f;
double y0 = ((4.0f * (j - (width / 2))) / (width)) + 0.0f;
double x = 0.0f;
double y = 0.0f;
int iteration = 0;
int max_iteration = 15;
while ((((x * x) + (y * y)) <= 4.0f) && (iteration < max_iteration))
{
double xtemp = ((x * x) - (y * y)) + x0;
y = ((2.0f * x) * y) + y0;
x = xtemp;
iteration += 1;
}
thing(j, i, iteration, max_iteration);
}
}
It was my understanding that x0 should be in the range -2.5 - 1 and y0 should be in the range -1 - 1, and that reducing that number would zoom, but that didnt really work at all. How can I zoom?
Suppose the center is the (cx, cy) and the length you want to display is (lx, ly), you can use the following scaling formula:
x0 = cx + (i/width - 0.5)*lx;
y0 = cy + (j/width - 0.5)*ly;
What it does is to first scale down the pixel to the unit interval (0 <= i/width < 1), then shift the center (-0.5 <= i/width-0.5 < 0.5), scale up to your desired dimension (-0.5*lx <= (i/width-0.5)*lx < 0.5*lx). Finally, shift it to the center you given.
first off, with a max_iteration of 15, you're not going to see much detail. mine has 1000 iterations per point as a baseline, and can go to about 8000 iterations before it really gets too slow to wait for.
this might help: http://jc.unternet.net/src/java/com/jcomeau/Mandelbrot.java
this too: http://www.wikihow.com/Plot-the-Mandelbrot-Set-By-Hand