I want to generate some randoms polygon but I want it to be more or less centered in the middle of the given window coordinates.
Here is my code, it generates a random polygon but most of the time it's on the bottom of the window and I'd like to have it a bit more centered:
private static final double CORNER_MARGIN = 100.0; // max offset for a corner of the field, to randomize the polygon
private static double[] standardPolygon(double x1, double x2, double y1, double y2) {
// minX maxX minY maxY --> it's the coordinate of the window
double centerX = (x1 + x2) / 2;
double centerY = (y1 + y2) / 2;
// this is a standard polygon "centered" in the middle of the program window
return new double[]{
x1 - (x2 - x1) * RANDOM.nextDouble(), y2 + (y2 - y1) *RANDOM.nextDouble() * CORNER_MARGIN,
x2 + (x2 - x1) * RANDOM.nextDouble(), y2 + (y2 - y1) *RANDOM.nextDouble() * CORNER_MARGIN,
x2 + (x2 - x1) * RANDOM.nextDouble(), y1 - (y2 - y1) *RANDOM.nextDouble() * CORNER_MARGIN,
x1 - (x2 - x1) * RANDOM.nextDouble(), y1 - (y2 - y1) *RANDOM.nextDouble() * CORNER_MARGIN,
};
/*return new double[]{
x1 - RANDOM.nextDouble() * CORNER_MARGIN, y2 + RANDOM.nextDouble() * CORNER_MARGIN, // up left
x2 + RANDOM.nextDouble() * CORNER_MARGIN, y2 + RANDOM.nextDouble() * CORNER_MARGIN, // up right
x2 + RANDOM.nextDouble() * CORNER_MARGIN, y1 - RANDOM.nextDouble() * CORNER_MARGIN, // down right
x1 - RANDOM.nextDouble() * CORNER_MARGIN, y1 - RANDOM.nextDouble() * CORNER_MARGIN, // down left
};*/
}
The code in comment is working but now I tried to center it but I only get some rectangles/squares. How can I manage to keep random polygon forms but a bit more centered ?
[EDIT]
Here is how I draw the area of the polygon :
private void drawZone(Group group, IGameParameters gameParameters) {
Polygon polygon = new Polygon();
double[] points = gameParameters.dronePadDeliveryZonePolygon();
List<Double> pointsList = new ArrayList<>();
for (double point : points) pointsList.add(point);
polygon.getPoints().addAll(pointsList);
polygon.setFill(Color.ANTIQUEWHITE);
group.getChildren().add(polygon);
}```
You calculated the center but don't use it anywhere. Just so I understand correctly, this is a 4-sided polygon only and the corners randomly positioned at most 100 from the corner of the window?
I'm not 100% sure on how you want the polygon to be shaped but give this a try. Logically it works in my head, but I don't have a way to test the code right now.
private static final double CORNER_MARGIN = 100.0;
private static double[] standardPolygon(double x1, double x2, double y1, double y2) {
double centerX = (x1 + x2) / 2;
double centerY = (y1 + y2) / 2;
// Get the corner offsets
ox1 = x1 + CORNER_MARGIN * RANDOM.nextDouble(); // top left
oy1 = y1 + CORNER_MARGIN * RANDOM.nextDouble();
ox2 = x2 - CORNER_MARGIN * RANDOM.nextDouble(); // top right
oy2 = y1 + CORNER_MARGIN * RANDOM.nextDouble();
ox3 = x1 + CORNER_MARGIN * RANDOM.nextDouble(); // bottom left
oy3 = y2 - CORNER_MARGIN * RANDOM.nextDouble();
ox4 = x2 - CORNER_MARGIN * RANDOM.nextDouble(); // bottom right
oy4 = y2 - CORNER_MARGIN * RANDOM.nextDouble();
// Calculate the center of the polygon
double cx = (ox2 - ox1) / 2;
double cy = (oy2 - oy1) / 2;
// difference between window's center and polygon
double offsetX = centerX - cx;
double offsetY = centerY - cy;
// offset the calculated points so the polygon's center matches the window
ox1 += offsetX;
oy1 += offsetY;
ox2 += offsetX;
oy2 += offsetY;
ox3 += offsetX;
oy3 += offsetY;
ox4 += offsetX;
oy4 += offsetY;
// this is a standard polygon "centered" in the middle of the program window
return new double[]{
ox1, oy1,
ox2, oy2,
ox3, oy3,
ox4, oy4
};
}
I am trying to draw an arc on Jpanel in swing from user input having the center of arc, starting point and end point of arc.
here is my current
int x1 = 300; //start point
int y1 = 300;
int x2 = 350; //center point of arc
int y2 = 350;
int x3 = 300; //end point of arc
int y3 = 400;
int h1 = y1 - y2; //calculate with and height from start-center and center-end
int d1 = x2 - x1;
int h2 = y2 - y3;
int d2 = x3 - x2;
int startangle = (int)(Math.atan(h1 / d1) * 180 / Math.PI);
if (x2 > x1 && y2 > y1) {
startangle = 180 - startangle;
} else if (x2 < x1) {
//change sign
} else if (y1 < y2) {
//change sign
}
System.out.println("x1,y1\n" + x1 + "\n" + y1 + "\n" + d2 / h2 + "\n" + Math.atan(d2 / h2) * 180 / Math.PI);
int endangle = (int)(Math.atan2(x3, y3) * 180 / Math.PI);
System.out.println("args: " + "\n" + x2 + "\n" + y2 + "\n" + startangle + "\n" + endangle + "\n");
g2.drawArc(x1, y1, d1, h1, startangle, startangle);
g2.drawArc(x2, y2, d2, h2, 0, endangle);
However i am not getting the arc on screen, literally nothing related to it (other shapes work but not this one). No errors or exceptions were thrown.
Edit: Thanks to #MadProgrammer's comment, i am getting a shape but not what i expect.
What i get:
What i expect from the same set of coordinates:
Edit 2: managed to make it work by using a bezier curve instead of an arc
It worked by using a bezier curve and drawing quadcurve in two phases (start-middle,middle-end) using the calculated control points instead of the drawArc method.
I think the bounding rectangle of drawarc is the height and width of the ellipse that your arc is part of.
I'm trying to make an Asteroids remake using Java and I'm having problems making the player (which is a triangle) rotate when I press a button. I have looked up methods and the math to make the points of the triangle rotate but I haven't figured out how to use the formulas. Your help will be greatly appreciated. Thank You!
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import Main.GameObject;
import Main.ID;
public class Player extends GameObject {
public float x1 = 16 + xPos;
public float y1 = 0 + yPos;
public float x2 = 0 + xPos;
public float y2 = 48 + yPos;
public float x3 = 32 + xPos;
public float y3 = 48 + yPos;
public float centerX = xPos + 16;
public float centerY = yPos - 24;
public Point2D.Float center = new Point2D.Float(xPos + 16, yPos - 24);
public Point2D.Float p1 = new Point2D.Float(x1, y1);
public Point2D.Float p2 = new Point2D.Float(x2, y2);
public Point2D.Float p3 = new Point2D.Float(x3, y3);
public Player(float startX, float startY, ID id) {
super(startX, startY, id);
this.xPos = startX;
this.yPos = startY;
this.id = id;
}
public void tick() {
}
public void render(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.WHITE);
g2.draw(new Line2D.Float(p1, p2));
g2.draw(new Line2D.Float(p2, p3));
g2.draw(new Line2D.Float(p3, p1));
}
public Rectangle getBounds() {
return null;
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT) {
//Rotate triangle here
}
}
}
To rotate a single point around the origin (0,0).
float rot = 2.0; // angle in radians
Point2D.Float p1 = new Point2D.Float(10.0,10.0);
Point2D.Float p1Rotated = new Point2D.Float(0,0);
float dx = Math.cos(rot);
float dy = Math.sin(rot);
p1Rotated.x = p1.x * dx + p1.y * -dy;
p1Rotated.y = p1.x * dy + p1.y * dx;
So for a triangle that has its center at 0,0 do the above to each point then position the triangle by adding the offset to each point.
float rot = 2.0; // angle in radians
float x = 100.0; // space ship center at 100,100
float y = 100.0;
Point2D.Float p1 = new Point2D.Float(10.0,10.0);
Point2D.Float p2 = new Point2D.Float(-10.0,10.0);
Point2D.Float p3 = new Point2D.Float(0.0,-10.0);
Point2D.Float p1R = new Point2D.Float(0,0);
Point2D.Float p2R = new Point2D.Float(0,0);
Point2D.Float p3R = new Point2D.Float(0,0);
float dx = Math.cos(rot);
float dy = Math.sin(rot);
p1R.x = p1.x * dx + p1.y * -dy + x;
p1R.y = p1.x * dy + p1.y * dx + y;
p2R.x = p2.x * dx + p2.y * -dy + x;
p2R.y = p2.x * dy + p2.y * dx + y;
p3R.x = p3.x * dx + p3.y * -dy + x;
p3R.y = p3.x * dy + p3.y * dx + y;
I wrote a program which draws a circle colored thanks to a chromatic gradation, using the Andres' algorithm. Here is an execution's result :
Now I would want to shift this gradation. For example, I would want the red to begin at the right of the circle. Or at 70°. Etc.
So I have a shift, in radians. And I must use it in my Andres' algorithm.
But I don't understand how. However, I see two ways to do that :
Either I change the Andres' algorithm, I mean I change the coordinates of each pixel of each octant (= I change the circle's drawing) ;
Or I really shift the gradation and not the drawing.
I would prefer the solution number one. And I know it will make use of trigonometry. But my skills are too bad and I really need your help please...
Here is the source of my Andres' implementation. If you need it, I can also show you the code of my gradation-function. Thank you in advance.
NB : the most important part is just below the line while (y >= x) (id est : the octants' coordinates).
case "Andres' algorithm":
w = 2 * Math.PI;
for(double current_thickness = 0; current_thickness < this.thickness; current_thickness++) {
x = 0;
y = (int) (radius + current_thickness);
double d = radius + current_thickness - 1;
while (y >= x) {
double octant_1_x = x0 + x, octant_1_y = y0 + y;
double octant_2_x = x0 + y, octant_2_y = y0 + x;
double octant_3_x = x0 - x, octant_3_y = y0 + y;
double octant_4_x = x0 - y, octant_4_y = y0 + x;
double octant_5_x = x0 + x, octant_5_y = y0 - y;
double octant_6_x = x0 + y, octant_6_y = y0 - x;
double octant_7_x = x0 - x, octant_7_y = y0 - y;
double octant_8_x = x0 - y, octant_8_y = y0 - x;
max_counter++;
double[] rgb_gradation_octant_1 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_1_y - y0, octant_1_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_1_x, octant_1_y, Color.color(rgb_gradation_octant_1[0], rgb_gradation_octant_1[1], rgb_gradation_octant_1[2]))); // octant n°1
double[] rgb_gradation_octant_2 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_2_y - y0, octant_2_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_2_x, octant_2_y, Color.color(rgb_gradation_octant_2[0], rgb_gradation_octant_2[1], rgb_gradation_octant_2[2])));
double[] rgb_gradation_octant_3 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_3_y - y0, octant_3_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_3_x, octant_3_y, Color.color(rgb_gradation_octant_3[0], rgb_gradation_octant_3[1], rgb_gradation_octant_3[2])));
double[] rgb_gradation_octant_4 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_4_y - y0, octant_4_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_4_x, octant_4_y, Color.color(rgb_gradation_octant_4[0], rgb_gradation_octant_4[1], rgb_gradation_octant_4[2]))); // octant n°4
double[] rgb_gradation_octant_5 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_5_y-y0, octant_5_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_5_x, octant_5_y, Color.color(rgb_gradation_octant_5[0], rgb_gradation_octant_5[1], rgb_gradation_octant_5[2]))); // octant n°5
double[] rgb_gradation_octant_6 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_6_y-y0, octant_6_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_6_x, octant_6_y, Color.color(rgb_gradation_octant_6[0], rgb_gradation_octant_6[1], rgb_gradation_octant_6[2])));
double[] rgb_gradation_octant_7 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_7_y-y0, octant_7_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_7_x, octant_7_y, Color.color(rgb_gradation_octant_7[0], rgb_gradation_octant_7[1], rgb_gradation_octant_7[2])));
double[] rgb_gradation_octant_8 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_8_y-y0, octant_8_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_8_x, octant_8_y, Color.color(rgb_gradation_octant_8[0], rgb_gradation_octant_8[1], rgb_gradation_octant_8[2]))); // octant n°8
if (d >= 2 * x) {
d -= 2 * x + 1;
x++;
} else if (d < 2 * (radius + thickness - y)) {
d += 2 * y - 1;
y--;
} else {
d += 2 * (y - x - 1);
y--;
x++;
}
}
}
gui.getImageAnimation().setMax(max_counter*8);
break;
In 2 dimensions, you can achieve rotation with the following formulas:
x' = x cos f - y sin f
y' = y cos f + x sin f
Instead of repeating the transformation in every Pixel instantiation, you could write a helper that creates a rotated pixel and returns it. I meant something like:
Pixel rotated_pixel (double x, double y, Pixel rotation_center, Color color, double angle) {
double x0 = rotation_center.x,
y0 = rotation_center.y, // Oh god I hope I'm not also wrong about the field names now
sinw = Math.sin(angle), cosw = Math.cos(angle),
x_rot = x0 + (x-x0)*cosw - (y-y0)*sinw,
y_rot = y0 + (y-y0)*cosw + (x-x0)*sinw;
return new Pixel(x_rot, y_rot, color); // or smth
}
Then you can use it like updates.add(rotated_pixel(x,y,whatever));
I'm sorry that I cannot check the validity of this code; I don't currently have access to a computer with Java.
Thanks to #kubuzetto , the code below allows me to draw a circle taking account of a shift, expressed in radians. I mean its drawing begins at a certain angle (which is the shift). I still use Andres.
The only new problem with this solution is that gaps appear when the circle is rotated (ie. : when there is a shift).
Indeed :
http://imgur.com/BcAsP9n
I thought it was because of a cast which would have decreased the precision of the coordinates, but it's not the case.
If someone see why there is this problem, it would be fine !
/**
* Constructs a Pixel taking account of a shift and near the position (x0 ; y0)
* #param x
* #param y
* #param color
* #param angle
* #param x0
* #param y0
*/
Pixel(double x, double y, Color color, double angle, double x0, double y0) {
this.x = (int) (x0 + (x-x0) * Math.cos(angle) - (y-y0) * Math.sin(angle));
this.y = (int) (y0 + (y-y0) * Math.cos(angle) + (x-x0) * Math.sin(angle));
this.color = color;
}
And the Andres' algorithm :
case "Andres' algorithm":
w = 2 * Math.PI;
for(double current_thickness = 0; current_thickness < this.thickness; current_thickness++) {
x = 0;
y = (int) (radius + current_thickness);
double d = radius + current_thickness - 1;
while (y >= x) {
double octant_1_x = x0 + x, octant_1_y = y0 + y;
double octant_2_x = x0 + y, octant_2_y = y0 + x;
double octant_3_x = x0 - x, octant_3_y = y0 + y;
double octant_4_x = x0 - y, octant_4_y = y0 + x;
double octant_5_x = x0 + x, octant_5_y = y0 - y;
double octant_6_x = x0 + y, octant_6_y = y0 - x;
double octant_7_x = x0 - x, octant_7_y = y0 - y;
double octant_8_x = x0 - y, octant_8_y = y0 - x;
max_counter++;
double[] rgb_gradation_octant_1 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_1_y - y0, octant_1_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_1_x, octant_1_y,
Color.color(rgb_gradation_octant_1[0], rgb_gradation_octant_1[1], rgb_gradation_octant_1[2]),
circle_gradation_beginning, x0, y0)); // octant n°1
double[] rgb_gradation_octant_2 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_2_y - y0, octant_2_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_2_x, octant_2_y,
Color.color(rgb_gradation_octant_2[0], rgb_gradation_octant_2[1], rgb_gradation_octant_2[2]),
circle_gradation_beginning, x0, y0));
double[] rgb_gradation_octant_3 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_3_y - y0, octant_3_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_3_x, octant_3_y,
Color.color(rgb_gradation_octant_3[0], rgb_gradation_octant_3[1], rgb_gradation_octant_3[2]),
circle_gradation_beginning, x0, y0));
double[] rgb_gradation_octant_4 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_4_y - y0, octant_4_x - x0) + Math.PI, w);
updates.add(new Pixel(octant_4_x, octant_4_y,
Color.color(rgb_gradation_octant_4[0], rgb_gradation_octant_4[1], rgb_gradation_octant_4[2]),
circle_gradation_beginning, x0, y0)); // octant n°4
double[] rgb_gradation_octant_5 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_5_y-y0, octant_5_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_5_x, octant_5_y,
Color.color(rgb_gradation_octant_5[0], rgb_gradation_octant_5[1], rgb_gradation_octant_5[2]),
circle_gradation_beginning, x0, y0)); // octant n°5
double[] rgb_gradation_octant_6 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_6_y-y0, octant_6_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_6_x, octant_6_y,
Color.color(rgb_gradation_octant_6[0], rgb_gradation_octant_6[1], rgb_gradation_octant_6[2]),
circle_gradation_beginning, x0, y0));
double[] rgb_gradation_octant_7 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_7_y-y0, octant_7_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_7_x, octant_7_y,
Color.color(rgb_gradation_octant_7[0], rgb_gradation_octant_7[1], rgb_gradation_octant_7[2]),
circle_gradation_beginning, x0, y0));
double[] rgb_gradation_octant_8 = PhotoRetouchingFormulas.chromatic_gradation(Math.atan2(octant_8_y-y0, octant_8_x-x0) + Math.PI, w);
updates.add(new Pixel(octant_8_x, octant_8_y,
Color.color(rgb_gradation_octant_8[0], rgb_gradation_octant_8[1], rgb_gradation_octant_8[2]),
circle_gradation_beginning, x0, y0)); // octant n°8
if (d >= 2 * x) {
d -= 2 * x + 1;
x++;
} else if (d < 2 * (radius + thickness - y)) {
d += 2 * y - 1;
y--;
} else {
d += 2 * (y - x - 1);
y--;
x++;
}
}
}
gui.getImageAnimation().setMax(max_counter*8);
break;
Here is the circle class:
public class Circle {
private double radius;
private double x;
private double y;
}
How can I tell if two objects from this class (circles) are colliding?
P.S. Can you use the method that avoids taking a square root?
double xDif = x1 - x2;
double yDif = y1 - y2;
double distanceSquared = xDif * xDif + yDif * yDif;
boolean collision = distanceSquared < (radius1 + radius2) * (radius1 + radius2);
dx = x2 - x1;
dy = y2 - y1;
radiusSum = radius1 + radius2;
return dx * dx + dy * dy <= radiusSum * radiusSum; // true if collision
The link from #instanceofTom in the comments is better... with pictures.
The circles will touch when the distance between their centres is equal to the sum of their radii, or collide when the distance is less.
Since we are using absolute distance, it is Ok to compare the square of the distance between centres with the square of the sum of the radii.
Here's the updated Java solution:
public boolean hasCollision(Circle circle){
double xDiff = x - circle.getX();
double yDiff = y - circle.getY;
double distance = Math.sqrt((Math.pow(xDiff, 2) + Math.pow(yDiff, 2)));
return distance < (radius + circle.getRadius());
}