Check If image overlaps another image

@dreamer84Feb 24.2006

Hi,

I’m trying to make a script for a pixel ad site. So far I have come up with this;

On the index page:

When you click on the image on this page it takes you to buy.php

on buy.php there is a form with the x location and y location of the image that was clicked on, heres what this looks like:

<?php
$xloc = $_POST[‘whereami_x’]; // x co-ordinate
$yloc = $_POST[‘whereami_y’]; // y co-ordinate

//this is making the grid give blocks of 10 pixels. so first block is 0,0 next box is 1,0 and so on.
$x_loc = floor($xloc/10);
$y_loc = floor($yloc/10);

echo ‘<br />x =’.$x_loc;
echo ‘<br />y =’.$y_loc;
?>

On the form the customer can choose number of horizontal and vertical blocks for their image. Once they submit form it goes to confirm.php. Now, this is where I’m having a problem. On confirm.php I want it to check if the the number of blocks the customer chose would overlap an image of an existing customer (I have a table in mysql database that stores x and y locations, number of width blocks and height blocks of existing customers). I have absolutely no idea how to do this.
I would apreciate if anyone can give me any ideas or suggestions on this.

Many thanks in advance

to post a comment

PHP

4 Comments(s) _↴

@SpectreReturnsFeb 25.2006 — #I'd extract all of the blocks and who owns them from the database and put it into a 2D array, something like:

[code=php]// nobody owns it
 $map[$y][$x] == null
 /* OR */
 // somebody owns it
 $map[$y][$x] == $owner[/code]

Now, you'd need to go through every block and make sure it isn't owned, something like this:

[code=php]$map = ...; // populate the $map variable
 $good = true;
 $width = count($map[0]);
 $height = count($map);
 
 for ($y=0; $y<$height; $y++) {
 for ($x=0; $x<$width; $x++) {
 if ($map[$y][$x] != null) {
 $good = false;
 break 2;
 }
 }
 }
 
 if ($good) {
 echo "The region is good!";
 } else {
 echo "The region countains already owned blocks. :(";
 }[/code]

@dreamer84authorFeb 26.2006 — #Hey SpectreReturns,

Thank you for your reply. I just have a few questions and a request. I'm not sure how to populate the $map variable - is this the x and y data from the table of existing customers in db?

Are the variables $x and $y the data of the post variables or from the database?

Here is the code from confirm.php:

[code=php]<?php
 
 include 'pixeldb.php'; 
 # grab the POST variables from the HTML form, 
 
 $name = $_POST['name']; 
 $email = $_POST['email']; 
 $x1 = $_POST['x1']; 
 $y1 = $_POST['y1']; 
 $wblocks = $_POST['wblocks'];
 $hblocks = $_POST['hblocks'];
 $url = $_POST['url'];
 $message = $_POST['message'];
 $amount = $_POST['amount'];
 
 
 # Any escaped characters? No, not a jailbreak...something that could 
 # cause errors when PHP processes. We check for that here. 
 $name = stripslashes($name); 

 $email = stripslashes($email); 
 $x1 = stripslashes($x1); 
 $y1 = stripslashes($y1); 

 $wblocks = stripslashes($wblocks); 
 $hblocks = stripslashes($hblocks); 
 $url = stripslashes($url); 
 $message = stripslashes($message); 

 $amount = stripslashes($amount); 
 
 ?>[/code]

I have a table named 'customer' in mysql db, with the fields 'x_pos', 'y_pos', 'width_blocks' and 'height_blocks' and fields for other customer details.

If you can please show me an example of the code you posted with my variables above, that would clear a lot of confusion.

Also I'm not sure how to extract all of the blocks from the database and put it into a 2D array.

Thank you

@SpectreReturnsFeb 26.2006 — #The map would be the information for every block, sorted like this:
[code=php]$map[{from database}y_pos][{from database}x_pos] = {from database}customer;[/code]

I'm writing this off my head, so it might work, but I suspect something like this to populate the map:

[code=php]$map = array();
 $map_width = 20; // the map is made up as a 20x20 grid
 $map_height = 20; // change these to suit how big your map should be
 
 $querytpl = "SELECT customer FROM the_table WHERE y_pos=%s"; // change the_table to the table you're working in
 
 for ($y=0; $y<$map_height; $y++) {
 $result = mysql_query(sprintf($querytpl, "$y")); // typecast so it responds to %s
 $row = mysql_fetch_row($result);
 foreach ($row as $x => $customer) {
 $map[$y][$x] = $customer;
 }
 }[/code]

Here's the version of my older code so it'll work with what you said:

[code=php]include 'pixeldb.php';
 
 $postfields = array("name", "email", "x1", "y1", "wblocks", "hblocks", "url", "amount", "message");
 
 foreach ($postfields as $field) {
 $$field = stripslashes($_POST[$field]);
 }
 // I just cut down all of your manual definitions for the POST variables
 
 
 $map = ...; // use the code above
 $good = true;
 
 for ($y=$y1; $y<($hblocks + $y1); $y++) {
 for ($x=$x1; $x<($wblocks + $x1); $x++) {
 if ($map[$y][$x] != null) {
 $good = false;
 break 2;
 }
 }
 }
 
 if ($good) {
 echo "The region is good!";
 } else {
 echo "The region countains already owned blocks. :(";
 }[/code]

@dreamer84authorMar 13.2006 — #Hi,

I've been trying the above code out and now I'm getting errors.

These are the errors I'm having trouble fixing:

Notice: Undefined variable: customer in C:Websitesconfirm.php on line 61

Warning: mysql_fetch_row(): supplied argument is not a valid MySQL result resource in C:Websitesconfirm.php on line 75

Warning: Invalid argument supplied for foreach() in C:Websitesconfirm.php on line 76

Line 61:
[code=php]$map['ypos']['xpos'] = $customer;[/code]

Line 75:
[code=php]$row = mysql_fetch_row($result);[/code]

Line 76:

[code=php] foreach ($row as $x => $customer) {
 $map[$y][$x] = $customer;
 }
 } [/code]

Here's the entire php code from confirm.php:

[code=php]<?php
 include 'pixeldb.php';
 
 $query = "SELECT * FROM transaction"; 
 $data = mysql_query($query) or die (mysql_error()."<br />Couldn't execute query: $query"); 

 $map = mysql_fetch_array($data);
 
 
 $map['ypos']['xpos'] = $customer; 
 
 
 $map = array();
 $map_width = 20; // the map is made up as a 20x20 grid
 $map_height = 20; // change these to suit how big your map should be
 
 $querytpl = "SELECT name FROM transaction WHERE y_pos=%s"; // change the_table to the table you're working in
 
 for ($y=0; $y<$map_height; $y++) {
 $result = mysql_query(sprintf($querytpl, "$y")); // typecast so it responds to %s
 $row = mysql_fetch_row($result);
 foreach ($row as $x => $customer) {
 $map[$y][$x] = $customer;
 }
 } 
 
 
 
 $good = true;
 
 for ($y=$y1; $y<($hblocks + $y1); $y++) {
 for ($x=$x1; $x<($wblocks + $x1); $x++) {
 if ($map[$y][$x] != null) {
 $good = false;
 break 2;
 }
 }
 }
 
 if ($good) {
 echo "The region is good!";
 } else {
 echo "The region contains already owned blocks. :(";
 } 
 
 ?>[/code]

Also in #PHP _↴

Need Help With Add Comment Part Of Site Uploading Multiple Files to Separate Locations Does DB have to be full text for this kind of search query?

Success!

Help @dreamer84 spread the word by sharing this article on Twitter...

Tweet This

Check If image overlaps another image

4 Comments(s) _↴

Also in #PHP _↴

Success!

Social

Version

Check If image overlaps another image

4 Comments(s) ↴

Also in #PHP ↴

Success!

The web is an endless sea of information. Don't miss the boat... Subscribe!

Social

Version

4 Comments(s) _↴

Also in #PHP _↴