Cartesian Coordinates

Ok, let me start by saying that I am really really new to Java programming. For my first coding project (outside of the tutorials) I want to create a 2D Cartesian map. I am at a loss though of where to go next.
The class I built to hold the user given information is:
public class GridParameters{
/* These variables are going to be used to generate the first layer of the
* program, the grid. For testing purposes the grid origins can be 0,0 with
* rotation of zero. The scale MUST be greater than 0!*/
public int originEasting = 0;
public int originNorthing = 0;
public int gridRotation = 0;
public int gridScale = 1;
Ok... so I guess the first question is: How do I get the user information from the form I created, into these fields? And the second: How would I get the grid displayed on the screen? I know these are broad broad questions, but like I said, I am really new, and just looking for a nod in the right direction.

Stop, and do this tutorial right now: http://java.sun.com/docs/books/tutorial/2d/index.html

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Message Edited by altenbach on 06-30-2006 12:07 AM
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Shane, I can fully reproduce this in LabVIEW 8.5.1, so I think it is a bug.
Such a VI should NOT output stale data if the inputs are empty arrays!
Attached is a demonstration of the problem and workaround using complex math.
(I strongly prefer using complex data for xy graph. It is so much cleaner. )
Message Edited by altenbach on 08-12-2008 12:22 PM
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Attachments:
RotateBug.png ‏14 KB
2d_Rotate_bugMOD.vi ‏23 KB

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Need to isolate error with output with valid input (code included)

Hey guys, this code will be a bit lengthy as I am posting from two separate Java files: Rectangle.java and RectangleTest.java - Basically I am stumped as to why even valid input keeps resulting in this message: System.out.println("\nThis is a SQUARE, not a Rectangle...Quiting...\n"); . Why am I getting this output? I seriously cant figure this out, and really what I am trying to do is take user input for four sets of coordinates, store them, do some simple math with them to determine if the object they form is a Rectangle and not a square. In the long run I am probably doing the whole thing wrong.
Here is the Rectangle.java code:
public class Rectangle {
     private int x1,x2,x3,x4,y1,y2,y3,y4;
     private int length;
     private int width;
     public Rectangle ()
          this.x1 = 0;
          this.y1 = 0;
          this.x2 = 0;
          this.y2 = 0;
          this.x3 = 0;
          this.y3 = 0;
          this.x4 = 0;
          this.y4 = 0;
     public Rectangle ( int x1, int x2, int x3, int x4, int y1, int y2, int y3, int y4)
          this.setX1(x1);
          this.setX2(x2);
          this.setX3(x3);
          this.setX4(x4);
          this.setY1(y1);
          this.setY2(y2);
          this.setY3(y3);
          this.setY4(y4);
          // First set x1, y1
          if (x1 > 0 && x1 < 20)
               setX1(x1);
          else
               this.x1 = 0;
          if (y1 > 0 && y1 < 20)
               setY1(y1);
          else
               this.y1 = 0;
          // Second set x2,y2
          if (x2 > 0 && x2 < 20)
               setX2(x2);
          else
               this.x2 = 0;
          if (y2 > 0 && y2 < 20)
               setY2(y2);
          else
               this.y2 = 0;
          // Third set x3,y3
          if (x3 > 0 && x3 < 20)
               setX3(x3);
          else
               this.x3 = 0;
          if (y3 > 0 && y3 < 20)
               setY3(y3);
          else
               this.y3 = 0;
          // Last set x4,y4
          if (x4 > 0 && x4 < 20)
               setX4(x4);
          else
               this.x4 = 0;
          if (y4 > 0 && y4 < 20)
               setY4(y4);
          else
               this.y4 = 0;
     }// exit constructor
     // Enter methods
     public int getArea()
          return length * width;
     public int getPerimeter()
          return (2*length) + (2*width);
     public boolean isSquare()
          if (length == width)
                return true;
          else return false;
     public boolean isRectangle()
          if (length != width && length > width)
                return true;
          else return false;
     // Enter Setters and Getters
     public void setLength(){
          this.length = ((x2-x1)^2 + (y2-y1)^2);
     public int getLength(){
          return length;
     public void setWidth(){
          this.width = ((x4-x1)^2 + (y4-y1)^2);
     public int getWidth(){
          return width;
     public void setX1(int x1) {
          this.x1 = x1;
     public int getX1() {
          return x1;
     public void setX2(int x2) {
          this.x2 = x2;
     public int getX2() {
          return x2;
     public void setX3(int x3) {
          this.x3 = x3;
     public int getX3() {
          return x3;
     public void setX4(int x4) {
          this.x4 = x4;
     public int getX4() {
          return x4;
     public void setY1(int y1) {
          this.y1 = y1;
     public int getY1() {
          return y1;
     public void setY2(int y2) {
          this.y2 = y2;
     public int getY2() {
          return y2;
     public void setY3(int y3) {
          this.y3 = y3;
     public int getY3() {
          return y3;
     public void setY4(int y4) {
          this.y4 = y4;
     public int getY4() {
          return y4;
Code for RectangleTest.java:
import java.util.Scanner;
public class RectangleTest {
     public static void main(String[] args)
          int choice;
          int xFirst, xSecond, xThird, xFourth, yFirst, ySecond, yThird, yFourth;
          Scanner input = new Scanner(System.in); // Scans or reads the inputs from the keyboard of user
          do {
               System.out.print("\nTo START Enter '1'; ");
               System.out.print("\nOr to QUIT Enter '0'; ");
               choice = input.nextInt();
               if (choice == 1)
              // First Set
              System.out.println("\nPlease enter the FIRST set of Coordinates\n");
              System.out.print("Enter X1: ");
              xFirst = input.nextInt();
              System.out.print("Enter Y1: ");
              yFirst = input.nextInt();
              // Second Set
              System.out.println("\nPlease enter the SECOND set of Coordinates\n");
              System.out.print("Enter X2: ");
              xSecond = input.nextInt();
              System.out.print("Enter Y2: ");
              ySecond = input.nextInt();
              // Third Set
              System.out.println("\nPlease enter the THIRD set of Coordinates\n");
              System.out.print("Enter X3: ");
              xThird = input.nextInt();
              System.out.print("Enter Y3: ");
              yThird = input.nextInt();
              // Third Set
              System.out.println("\nPlease enter the FOURTH set of Coordinates\n");
              System.out.print("Enter X4: ");
              xFourth = input.nextInt();
              System.out.print("Enter Y4: ");
              yFourth = input.nextInt();
              // Instantiating the Rectangle class to test it
              Rectangle rectangle1 = new Rectangle(xFirst, xSecond, xThird, xFourth, yFirst, ySecond, yThird, yFourth);
              int lengthRectangle1 = rectangle1.getLength();
              int widthRectangle1 = rectangle1.getWidth();
              int area = rectangle1.getArea();
              int periRect = rectangle1.getPerimeter();
              // Check Shape type
              if (rectangle1.isRectangle())
                   System.out.println("\nThis is a valid Rectangle\n");
              else if (rectangle1.isSquare());
                    System.out.println("\nThis is a SQUARE, not a Rectangle...Quiting...\n");
     }while (choice != 0);
     System.out.println("Bye for now!");
}

NPP83 wrote:
Essentially, I am trying to achieve the following:
1. Store the Cartesian coordinates for the four corners of a Rectangle
2. Verify that the supplied coordinates (by the user) do infact make a Rectangle and not a Square.
Since I don't physically have a Length and Width, but just points, I have to use a little math to create a Length and Width and I came up with ((x2-x1)^2 + (y2-y1)^2) to find the length of one side. I thought I would store this as the way to set the Length/Width (setLength & setWidth), but I havent been able to find a way to bridge the user's input in the main() method of the test program to use the values in this formula. Even then, I am not sure if this simple step would at all help validate the object created by the four sets of points is a Rectangle. I thought that a Rectangle might be created by simply by deductive math where if the Length > Width or Length < Width and Width != Length then I would have a what I was looking for.One side is (X2 - X1) the next side is (Y3 - Y2) the 3rd and 4th sides are: (X4 - X3) and (Y4 - Y1).
Edited by: morgalr on Mar 29, 2010 3:40 PM -- the following comment added:
You should check out getBounds, it may be what you are looking for.

Very Basic Objective-C issue, I am sure

So I picked up a book on ojective-c namely Mr. Kochan's, and have been trying to work through the exercises and examples. I ran into my first problem that I haven't been able to solve myself. The error says that the object I tried to create "point" is being redeclared as a different type of symbol. Although I can swear I have the section from the book copied almost verbatim, I am sure I am doing something overtly wrong, but I still can't find it. Any suggestions would be greatly appreciated.
Thanks in advance!
Here is the code I am working with sans the header:
#import <stdio.h>
#import <objc/Object.h>
//--------------Interface Section----------
@interface Point: Object
int hcoord;
int vcoord;
-(void) print;
-(void) setHcoord: (int) x;
-(void) setVcoord: (int) y;
@end
//-------- Implementaion Section-------------
@implementation Point;
-(void) print
printf (" %i,%i", hcoord, vcoord);
-(void) setHcoord: (int) h
hcoord = h;
-(void) setVcoord: (int) v
vcoord = v;
@end
//--------- program section------------
int main (int argc, char *argv[])
Point *point1 = [[Point alloc] init];
[point1 setHcoord: 4];
[point1 setVcoord: 5];
printf ("The cartesian coordinates for point 1 are:");
[point1 print];
printf ("\n");
[point1 free];
return 0;
12" Powerbook Mac OS X (10.4.7)

OK. I think I see what's going on. Point is already declared in the Core Foundation, which is included in your project. If you're following the directions on page 10 of Kochan's book, they're kind of out of date.
I can get your program to build and run if I follow these steps:
1. Create a new project in Xcode. But instead of choosing a "Cocoa Application" like the book says, scroll down to the section that says "Command Line Utility". You want a "Foundation Tool".
2. In your "Source" folder in Xcode, you'll see two files, one with ".m" on the end, the other with "Prefix.pch" at the end. Open the ".m" file and replace everything with your code. Close and save the ".m" file.
3. Now, open the other file (the one ending with "_Prefix.pch" in your "Source" folder. There is a comment at the top, then three lines:
<pre class="command">#ifdef _OBJC_
#import <Foundation/Foundation.h>
#endif</pre>Comment out those three lines like so:
<pre class="command">//#ifdef _OBJC_
// #import <Foundation/Foundation.h>
//#endif</pre>Your project should compile and run. Alternatively, since Point is already defined, you can just change the name from Point something else.
Instead of step 3 above, just replace Point with something like MyPoint. Even just changing the "P" to a lower case "p" is enough to fix it.
charlie
P.S. -- If you haven't already visited, I suggest checking out Steve Kochan's page for that book. Pay special attention to the Errata section. There are some errors in the book and the corrections are there, so that's a good resource.

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My request is to have a big size so much as possible!

227.54" is the maximum dimension in Illustrator.
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Width tool

Why is it when using the width tool and after you expand the stroke, there's tons of anchor points? I understand that the anchors follow the path but it's got a ton of anchors which make it impossible to clean up. What's the ideal way to clean up all these anchors? ( sorry not the smooth tool or the simplify tool, something more precise perhaps?)
My second question is how can you make strokes that have the same width using the width tool? I understand there is the width tool dialog box where you can input values but if the stroke is slightly more twisted than the first stroke and yet I want to keep it uniform how would I go about using the width tool?
Thanks!

What's the ideal way to clean up all these anchors?
The ideal way is to actually draw the shapes you actually want, rather than rely upon automated features. Assuming at least an intermediate-level proficiency, you'll always end up with more elegant and efficient paths. And yes, it will take longer.
1. simple stroke
2. width points added ther's only 5 there
3. stroke expanded, see the tons of anchor points there?
You are familiar with the ability to turn on/off the display of anchor points with the Show/Hide Edges command, aren't you? Just because the program doesn't display all the actual anchor points involved as you instead manipulate the displayed controls for all these instant-gratification effects (auto-tracing, envelopes, stroke width) doesn't mean they're not there. Like it or not, they're being automatically created as you do those other-interface manipulations.
Why is it…?
Because an automated routine cannot read your mind. It doesn't know anything about how many anchorPoints are "ideal" for you to manipulate afterwards, as opposed to how accurately you want it to maintain the same shape it originally automatically generated.
Do a little research. Read up on how cubic Bezier curves work. Four Cartesian coordinate pairs (a startPoint, two handles, an endPoint) form a "hull" in which a curve is plotted, live, on any given grid resolution. Each set of four coordinate pairs are one Bezier curve; one segment of your squiggly path.
Now imagine trying to reverse-engineer that. Start with the particular plotted results on a particular grid (your monitor). Then try to determine from that four coordinate pairs which would yield a curve that would result in that plot. But wait…that's not really what your new demand (for fewer segments) requires: You have to figure out where to break the overall path into fewer segments (fewer sets of just four coordinate pairs). You have to figure out the coordinate pairs for a hull that would plot a curve not for each existing plotted result, but now one set for two segments; or one and a half segments; or three segments….
Some portions of the reverse-engineering may be relatively easy. Others may actually be impossible.
In other words, if it were possible to plot any shape you want with just four coordinate pairs, you'd never need multiple-segment paths, would you?
So after you've studied the math, then make that phone call to the software engineer and explain what he's missing.
JET

Cartesian Coordinates

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