I'm currently working on a program in class, but got stuck at a point where I have to use a for loop to draw the lines of the cube. Can anyone help me out a little here? I've looked online for help, but couldn't get help on this program using a FOR loop.
Original Question:
Write an application that draws a cube. Use class GeneralPath and method draw of class Graphics2D.
This is what I have down so far:
import java.awt.Color;
import java.awt.geom.GeneralPath;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public class CubeJPanel extends JPanel
{
public void paintComponent( Graphics g )
{
super.paintComponent( g );
// base one: coordinates for front of the cube, point 0, 1, 2, 3, 4
int base1X[] = { 100, 100, 200, 200, 100 };
int base1Y[] = { 100, 200, 200, 100, 100 };
// base two: coordinates for back of the cube, point 0, 1, 2, 3, 4
int base2X[] = { 75, 75, 175, 175, 75 };
int base2Y[] = { 75, 175, 175 ,75, 75 };
Graphics2D g2d = ( Graphics2D ) g;
g2d.setColor( Color.red );
GeneralPath cube = new GeneralPath();
// this is where i'm having trouble. I know i'm suppose to for loop and arrays to draw out the lines of the cube.
g2d.draw( cube );
} // end method paintComponent
} // end class CubeJPanel
The base1X, base1Y are x coordinates along a drawing area, with (0,0) being the top left corner of the panel. To use a GeneralPath you need to something like this:
GeneralPath cube = new GeneralPath();
cube.moveTo(base1x[0], base1y[0]);
for(int i=1; i<base1x.length(); i++)
{
cube.lineTo(base1x[i], base1y[i]);
}
cube.closePath();
The above code segment will draw a single square, which are all of the points in base1. Basically think of GeneralPath as connect the dots. You first have to move the path to a starting location. moveTo will move the drawer to the point, without drawing a line. The lineTo will draw a line from your current point to the point in the moveTo. Lastly, be sure to close the path.
Figure out the correct order to draw the points and you should be able to figure out how to iterate over the points.
Related
My teacher is having us write code to draw a logo on the screen using awt, swing, and the graphics class. I decided to draw the google drive symbol, but I am getting stuck on the yellow third.
public class DriveLogo extends JApplet
{
public void init()
{
JRootPane rootPane = this.getRootPane();
rootPane.putClientProperty("defeatSystemEventQueueCheck", Boolean.TRUE);
}
public void paint(Graphics g)
{
int num_rect_points = 4;
g.setColor(Color.black);
g.fillRect(0,0,getSize().width, getSize().height);
/*************************************Yellow 1/3**********************************/
//Order of vertices: Left, right, lower-right, lower-left
int p1x1 = 150, p1x2 = 250, p1x3 = 350, p1x4 = 300;
int p1y1 = 25, p1y2 = 25, p1y3 = 280, p1y4 = 280;
int[] poly_1_x = {
p1x1, p1x2, p1x3, p1x4
};
int[] poly_1_y = {
p1y1, p1y2, p1y3, p1y4
};
Polygon yellow = new Polygon(poly_1_x, poly_1_y, num_rect_points);
/*************************************Draw**********************************/
g.setColor(Color.yellow);
g.fillPolygon(yellow);
}
}
This produces the following result:
There should be a yellow rhombus/rectangle slanted to the left. I asked my teacher, and she reviewed my code, but could not isolate the problem, and told me it "should" be working. Should doesn't mean it is however, and this is a rather large grade. Spent most of two class periods and downloaded the project to my home computer to debug, but I just can't seem to figure out what the problem is.
Things I know; the polygon coordinates must be in order, so to draw a rectangle, I cannot list them top-left, bottom-right, bottom-left, top-right, but I can list them top-left, top-right, bottom-right, bottom-left.
Okay, I solved this by experimenting around. For whatever reason, the call to g.fillPolygon(Polygon p) was not working, but when I called g.fillPolygon(poly_1_x, poly_1_y, num_recto_points); it worked properly.
I am a beginner in Java Swing . I was trying to draw the graph of sin(x) in applet . I am surprised why applet always draws my axis only not my graph?
here is my code :
import java.applet.Applet;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
public class NewApplet extends Applet
{
public void init()
{
// TODO start asynchronous download of heavy resources
}
public void paint(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
//get dimension
Dimension appletSize = this.getSize();
// make the applet empty at start
g2.setBackground(Color.white);
g2.setColor(Color.white);
g2.fillRect(0, 0, appletSize.width, appletSize.height);
//now draw all you need
g2.setColor(Color.red);
//x axis
g2.drawLine(0, appletSize.height/2, appletSize.width, appletSize.height/2);
//y axis
g2.drawLine(appletSize.width/2, 0, appletSize.width/2, appletSize.height);
//function
g2.setColor(Color.black);
for(int k=0; k<=180; k++)
{
g2.drawString(".", (float) Math.toRadians(k), (float) Math.sin(Math.toRadians(k)));
}
}
}
I am plotting 180 points of sin(x) with String "." , but My applet didn't show a single plot.Why?
[ Mention if there any good practice I should follow or suggest me any good library (JAR) for drawing graphs ]
It actually draws a graph.
Since values sine are between -1 and +1, and the radian values are between0 +π and -π, so the graph is drawn at those coordinates.
If you change this line:
g2.drawString(".", (float) Math.toRadians(k), (float) Math.sin(Math.toRadians(k)));
to this line:
g2.drawString(".", (appletSize.height/2)+(float) Math.toRadians(k)*50, (appletSize.width/2)+(float) Math.sin(Math.toRadians(k))*50);
You will see half the graph (since you have written the code for half the graph.)
Here:
I add (appletSize.height/2) and (appletSize.width/2) to the values, to bring them to the center of the screen (on the graph)
I multiply them by 50 to make the graph large, else, the graph is too small to understand.
I've been looking for solutions in google with no success, I'm creating a small library (just a wrapper) for Box2D in LibGDX and I'm drawing a texture for each body, taking as base the Body.getPosition() vector, however, I see polygon's getPosition() is different respect to CircleShapes and the walls (which were created with setAsBox() method).
Here's an image:
http://i.stack.imgur.com/NzooG.png
The red points are the center of mass, the cyan circles are the geometric center (right?) given by body.getPosition(), as you can see I can adapt the texture to the body in terms of position, rotation and scale but this does not happen with polygons (except the ones made with setAsBox()).
Basically, what I want is to get the cyan circle in the AABB centre of the regular polygons. here's a runnable example:
import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.math.Vector2;
public class MyGdxGame extends ApplicationAdapter {
Tabox2D t;
float w ,h;
#Override
public void create () {
w = Gdx.graphics.getWidth();
h = Gdx.graphics.getHeight();
t = Tabox2D.getInstance();
t.debug = true;
t.newBall("d", 100, 200, 25);// Ball.
t.newBox("s", 10, 10, w - 20, 50);// Floor.
t.newHeptagon("d", new Vector2(200, 200), 40);
}
#Override
public void render () {
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
t.update(0);// Don't move anything just to see the cyan circle.
t.draw();
}
}
Tabox2D class is here: https://github.com/tavuntu/tabox2d
NOTE: this was tested with the last version of Android Studio and LibGDX.
Thanks in advance!
Looks to me like you are positioning the shapes on the centre point, instead of the body. The centre of the shapes should be 0,0, not center.x,y. Fixture positions are relative to the body.
OK, so I think I solved this maybe in an inelegant way. What I did was:
Create the polygons points around the origin
Get AABB center of polygon and centroid (not necessarily the same)
Translate points to make AABB center the shape center, so the image can be drawn respect to this and not the center of mass.
The code needs a lot of cleaning but it seems to work just well, updated code in github repo, thanks!
The change was basically translate points from the original centroid to AABB center:
for(int i = 0; i < pts.length - 1; i += 2) {
pts[i] -= aabbCenter.x;
pts[i + 1] -= aabbCenter.y;
}
My issues is the following: My actual project (of which the code below is a simplified version of) involves many concentric circles (each with a different colour) and animation utilising a Timer. The circles are drawn using the drawOval method.
My problem is that when these concentric circles are drawn, there appears to be loads of gaps in the outline of these circles, which I'm guessing is something to do with the fact that a circle is composed of pixels and lines as is any shape so the appearance of roundness is an illusion. I say this because when I swap the drawOval method for drawRect the painting looks as you would expect.
When messing around with other people's codes I saw that using RenderingHints somehow solved this problem however slowed down the animation beyond a point that I felt was acceptable.
Below is a screenshot of what is painted. Rather than seeing a solid opaque circle (as all of the circles drawn have the same colour in this example) we see this:
Here is my simplified code:
Test10
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
public class Test10 extends JPanel {
Circle[] circles;
public static void main(String[] args) {
new Test10().go();
}
void go() {
JFrame frame = new JFrame("Circle Test");
frame.getContentPane().add(this);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
circles = new Circle[200];
for (int i = 0; i < 200; i++) {
circles[i] = new Circle(i, ((2 * ( 200 - i) + 1)));
}
repaint();
frame.setPreferredSize(new Dimension(500,500));
frame.pack();
frame.setVisible(true);
}
public void paintComponent(Graphics g) {
for (Circle circle : circles ) {
circle.draw(g);
}
}
}
Circle
import java.awt.Graphics;
public class Circle {
int topLeft;
int diameter;
public Circle(int topLeft, int diameter) {
this.topLeft = topLeft;
this.diameter = diameter;
}
void draw(Graphics g) {
g.drawOval(topLeft, topLeft, diameter, diameter);
}
}
Could anyone explain to me a) Why this is happening and b) How to overcome this problem.
UPDATE
Having tried various methods including starting with the outermost circle and using fillOval instead of drawOval, and using a higher stroke value, I still find I have a problem with certain artefacts appearing similar to the screenshot Pavel posted. Here is a screenshot from my full application running the animation, if you look carefully you can see inconsistencies in the colour of mostly any given circle, resulting in these strange results. Their distribution actually follows the same pattern as the screenshot posted above so clearly something fundamental isn't being addressed by these options. Here is my screen shot:
It is impossible to draw perfect circle.
Try using the following method
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(2));
int i = 0;
for (Circle circle : circles ) {
Shape circle2 = new Ellipse2D.Double(i++, i, circle.diameter, circle.diameter);
g2d.draw(circle2);
}
}
You said you tried with RenderingHints, and it slowed your animation, but you haven't give us any code with animation, so maybe try my code (it would be good to see animation implementation). It looked better, but still not what you wanted. Setting stroke to another value will solve this (set to at least 2). Another one is to use .fill() instead of .draw(). I know that it is not perfect, but you may try it.
ANOTHER IDEA
I thought, that maybe you could add some blur to your image, so those artifacts are not visible?
I haven't done it before, but I found this (found HERE):
private class BlurGlass extends JComponent {
private JFrame f;
public BlurGlass(JFrame f) {
this.f = f;
setOpaque(false);
setFocusable(false);
}
public void paintComponent(Graphics g) {
int w = f.getWidth();
int h = f.getHeight();
setLocation(0, 0);
setSize(w, h);
g.setColor(new Color(0, 0, 0, 0.3f));
g.fillRect(0, 0, w, h);
}
}
now somwhere in go() method:
frame.setGlassPane(new BlurGlass(frame));
frame.getGlassPane().setVisible(true);
It looks a lot better for me. Play a bit with this GlassPane color (try changing .3f to some other value).
You might want to make the Stroke bigger. I've had luck with this in situations similar to yours
You can try by adding this line in your Circle class inside draw function:
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
//and draw the Oval on g2
Also another solution might be to fill the circles:
Ellipse2D.Double circle = new Ellipse2D.Double(x, y, diameter, diameter);
g2.fill(circle);
That happens because a computer cannot draw a perfect circle.
A computer uses square pixels to approximate a real circle but its just not possible to achieve perfection and that results in some pixels not being shown
Drawing a filled circle will help you
a detailed explanation
Can you please try fillOval method instead of drawOval.
g.fillOval(topLeft, topLeft, diameter, diameter);
Reverse your idea. Start with the outermost circle, then draw the inner circle and so on, finishing with the smallest circle. You should use fillOval in the process.
The other rendering hint that is often useful for circles/ovals is
g.setRenderingHint( RenderingHints. KEY_STROKE_CONTROL,
RenderingHints.VALUE_STROKE_PURE);
See my other answer with more details and example.
I got the head, one arm and the body. I am trying to make another arm using the same first two coordinates, which starts at the bottom of the head, but a negative last (but same number) last two coordinates. I assumed that if I made a negative version, it would just make an opposite version of the line. Instead, its just sticking straight up! I am confused on why this is happening.
import javax.swing.JComponent;
import java.awt.*;
import java.awt.geom.*;
public class StickFigure extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
Ellipse2D.Double head = new Ellipse2D.Double(5, 10, 50, 50);
g2.draw(head);
Line2D.Double body=new Line2D.Double(30,60, 30,150);
g2.draw(body);
Line2D.Double arm1=new Line2D.Double(30,60,75,75);
g2.draw(arm1);
Line2D.Double arm2=new Line2D.Double(30,60,-75,-75);
g2.draw(arm2);
}
}
That is the code that is giving me trouble. I am using a viewer which is the following:
import javax.swing.JFrame;
public class Viewer
{
public static void main(String[] arg)
{
JFrame frame = new JFrame();
frame.setSize(1000,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
StickFigure fig1=new StickFigure();
frame.add(fig1);
frame.setVisible(true);
}
}
Please let me know what I am doing wrong, I would greatly appreciate it.
Line2D.Double arm2=new Line2D.Double(30,60,-75,-75);
You need to think about what you're saying with -75 and -75. Remember those make a coordinate, and (0, 0) represents the top left corner in Swing (unless you're explicitly telling it not to). Those coordinates are offscreen to the northwest.
Try something like:
Line2D.Double arm2=new Line2D.Double(30,60, 45,75);
Try using a positive y last coordinate for both:
Line2D.Double arm1=new Line2D.Double(30,60,75,75);
g2.draw(arm1);
Line2D.Double arm2=new Line2D.Double(30,60,-75,75);
g2.draw(arm2);
You are right that -75 -75 "would just make an opposite version of the line", but when you alter both coordinates you get radial simmetry, that is simmetry around a point (the neck) hence one of your arm is low and the other is up. You want axial symmetry in this case, and for that you only need to flip one coordinate; since people's axis of symmetry is the spine, and it is vertical (y-direction) you need to flip coordinate x only.