So I am making a tetris game and one of the problems I am running into is piece rotation. I know I can just hard code it but thats not the right way to do it. The way the system works is I have a 2d array of an object 'Tile' the 'Tile' object has x, y coords, boolean isActive, and color. The boolean isActive basically tells the computer which tiles are actually being used (Since tetris shapes are not perfect quadrilaterals).
Here is how I would make a shape in my system:
public static Tile[][] shapeJ() {
Tile[][] tile = new Tile[3][2];
for (int x = 0; x < 3; x++) {
for (int y = 0; y < 2; y++) {
tile[x][y] = new Tile(false, Color.blue);
}
}
tile[0][0].setActive(true);
tile[0][0].setX(0);
tile[0][0].setY(0);
tile[1][0].setActive(true);
tile[1][0].setX(50);
tile[1][0].setY(0);
tile[2][0].setActive(true);
tile[2][0].setX(100);
tile[2][0].setY(0);
tile[2][1].setActive(true);
tile[2][1].setX(100);
tile[2][1].setY(50);
return tile;
}
Now I need to rotate this object, I do not know how to do that without hard coding the positions. There has to be an algorithm for it. Can anyone offer some help?
A good way that I used when writing a tetris clone is to use rotational matrices:
http://en.wikipedia.org/wiki/Rotation_matrix
So the coordinates (x',y') of the point (x,y) after rotation are:
x' = x*cos(theta) - y*sin(theta);
y' = x*sin(theta) + y*cos(theta);
Where theta is the angle of rotation(+-90 degrees or +-PI/2 radians for the java functions that I know)
In this case the blocks are rotated around the origin (0, 0) so you either have to have the coordinates of the block in special "block space" that then gets transposed onto "field space" or you take away the offset of the block so that it is centered at the origin every iteration.
I hope that helps, I am happy to answer specific questions in the comments.
Related
I am using libgdx for easy 3D game, I need check model is clicked.
It is my code:
public int getObject (int screenX, int screenY) {
Ray ray = cam.getPickRay(screenX, screenY);
int result = -1;
float distance = -1;
for (int i = 0; i < rooms.size; ++i) {
final GameObject instance = rooms.get(i);
instance.transform.getTranslation(position);
position.add(instance.center);
final float len = ray.direction.dot(position.x-ray.origin.x, position.y-ray.origin.y, position.z-ray.origin.z);
if (len < 0f)
continue;
float dist2 = position.dst2(ray.origin.x+ray.direction.x*len, ray.origin.y+ray.direction.y*len, ray.origin.z+ray.direction.z*len);
if (distance >= 0f && dist2 > distance)
continue;
if (dist2 <= instance.radius * instance.radius ) {
result = i;
distance = dist2;
}
}
return result;
}
It it sometimes work.
Is is my model:
http://www6.zippyshare.com/v/97501566/file.html
What do I wrong?
Any help for me?
I am new with libgdx.
When was I press 1 it lights, but when I waas press 2, 1 lights too (instead 2)...
I didn't fully analyze your code nor do I know what It it sometimes work. actually means (e.g. in which circumstances doesn't it work?) but you're using a bounding sphere for detecting whether the object has been clicked or not.
Assuming your calculations are correct (as I said, I didn't check them in depth) you still can have false positives or negatives since the only shape which is perfectly represented by a bounding sphere is ... well... a sphere.
That might be the source for click detection to work "sometimes".
If that is the case and you want more accurate detection you should either use different bound volumes, bounding volumne hierarchies or a rendering based approach (i.e. render the object id into some buffer, which would allow for pixel perfect selection).
UPDATE:
From your post update it seems that bounding spheres are not the problem here, since they should not overlap, unless your data is wrong - which you should check/debug.
So the problem might actually lie in your calculations. From the documentation it looks like the ray you get is projected into the scene (i.e. into world space) so you'd need to transform your objects' center into worldspace as well.
You're currently only applying the position but ignore rotation and scale thus the resulting position might be wrong. I'm sure there's some built-in transform code, so instead of transforming manually you should use that. Please check the docs on how to do that.
I believe this is more of a logic question than a java question, sorry.
My intent is rather straightforward, i want the ship to move and rotate with a matrix, with the bitmap ship1 being the center pivot of the rotation. The code works great except the pivot is off by a strange offset. (picture of conundrum linked at bottom)
The default value rotation at 0 works but all the other values seem to slide away from the center, with 180 being the furthest from the center.
centerX = playerValues[Matrix.MTRANS_X] + ship1.getWidth()/2;
centerY = playerValues[Matrix.MTRANS_Y] + ship1.getHeight()/2;
newRotation = ((float) Math.toDegrees(Math.atan2(fingery1 - centerY, fingerx1 - centerX)));
matrix.postRotate((newRotation - prevRotation), centerX, centerY);
prevRotation = newRotation;
if (fingerx1 > playerX) {
xspeed = 1;
} else
if (fingerx1 < playerX) {
xspeed = 0;
} else
if (fingery1 > playerY) {
yspeed = 1;
} else
if (fingery1 < playerY) {
yspeed = 0;
}
matrix.postTranslate(xspeed, yspeed);
matrix.getValues(playerValues);
I tried to draw how the relation of the bitmap looks at different angles. (the blue dot is where I intend to rotate the bitmap around, the arrow pointing right is the only correct one).
http://i.stack.imgur.com/2Yw76.png
Please let me know if you see any errors or any feedback helps! I just need a second pair of eyes on this because mine are going to explode soon.
Consider studying a good computer graphics text re matrix math. Foley and Van Dam is always a safe bet.
The matrix A is applied to point x with multiplication Ax. You have A = RT a rotation with translation post multiplied. The result is RTx which is R (T x) meaning the point is translated then rotated, when you probably meant the opposite.
Additionally it appears you are concatenating incremental changes repeatedly. Floating point errors will accumulate, visible as worsening distortions. Instead maintain orientation parameters x, y, theta for each ship. These are controlled by the UI. Set the matrix from these in each rendering. The transform will be rotation about the point (w/2, h/2) followed by translation to (x, y). But the matrix to effect this is the translation post multiplied by the rotation! Also you must reset the matrix for each ship.
I have a school assignment where I'm supposed to (among other things) rotate a polygon. I can not use any premade rotate functions, so I have an array of points. The array is set up like this:
intArray[2][amount_of_points] where intArray[0] equals the points x coordinate, and intArray[1] holds the y coordinates.
//x=pivot point x coordinate, y = pivot point y coordinate.
public int[][] rotate(int[][]matrix,int x, int y, double degrees){
double s=Math.sin(degrees);
double c=Math.cos(degrees);
for (int i=0;i<matrix.length;i++){
//translate to origin
int px=matrix[0][i]-x;
int py=matrix[1][i]-y;
//rotate
double xnew = (px*c)-(py*s);
double ynew = (px*s)+(py*c);
//translate back
px=(int)((xnew+x)+0.5);
py=(int)((ynew+y)+0.5);
matrix[0][i]=px;
matrix[1][i]=py;
}
This is my code so far, and it is definitely not working out for me. I tried to trim the code as much as I could. Any help would mean a lot!
edit: I'm not getting any errors when I run the code, no exceptions etc. The only problem is that the polygon isn't rotating the way I intend it to.
I've made a test polygon:
polyArray = new int [2][3];
polyArray[0][0]=400;
polyArray[1][0]=200;
polyArray[0][1]=300;
polyArray[1][1]=500;
polyArray[0][2]=500;
polyArray[1][2]=500;
Which I draw in a JPanel, then I run this array through the rotation method like this:
polyArray=mm.rotate(polyArray, polyArray[0][0], polyArray[1][0], Math.PI);
Using the top point as pivotpoint. The whole polygon is then deformed.
Although still not very clear on question, I feel your problem is with the loop.
matrix.length is 2. So, the code never uses these :
polyArray[0][2]=500;
polyArray[1][2]=500;
If you change the condition as below, it should work :
for (int i=0;i<matrix[0].length;i++)
I am working on a platformer game that will use tile maps, which I don't know if is a good idea!
I've made a neat tile map editor with tools for setting a spawn point etc. but now that I want to be able to test play the game after editing map and for future use I need of course integrate physics which I've done with Box2D which comes with LibGDX!
I am creating a method to create a collision map from tile map which has data if tile is collideable or not!
So I came up with this great idea:
loop through the map and if we find a colliding tile loop through its neighbor tiles and see if they're colliding too, and do this til noncolliding tile is found when we set width and height for the colliding rectangle
after we got bunch of rectangle I sort them in order from biggest square to smallest so we get biggest pieces and I add the rectangles to final list and check against the final rect if any of them overlaps with current body so I don't have overlapping bodys
But you know, code tells more than 1000 words, right?
public void createBody() {
List<Rectangle> allRects = new ArrayList<Rectangle>();
for(int x = 0; x < info.getWidth(); x++) {
for(int y = 0; y < info.getHeight(); y++) {
if(tiles[x][y].getInfo().isColliding()) {
int width = 1;
int height = 1;
//loop through neighbors horizontally
for(int i = 0; i < info.getWidth() - x; i++) {
if(!tiles[x + i][y].getInfo().isColliding()) {
//if tile is not clipped, we set width to i which is current x offset
width = i;
break;
}
}
//only if width is bigger than zero can the rect have any tiels..
if(width > 0) {
boolean breakingBad = false;
//loop through neighbors horizontally
for(int j = 0; j < info.getHeight() - y; j++) {
//loop though neigbors vertizally
for(int i = 0; i < width; i++) {
//check if tile is not colliding
if(!tiles[x + i][y + j].getInfo().isColliding()) {
//and if so, we set height to j which is current y offset
height = j;
//breaking bad aka leaving both loops
breakingBad = true;
break;
}
}
if(breakingBad) {
break;
}
}
}
if(width * height > 0)
allRects.add(new Rectangle(x, y, width, height));
}
}
}
Collections.sort(allRects, new Comparator<Rectangle>() {
#Override
public int compare(Rectangle o1, Rectangle o2) {
Integer o1Square = o1.width * o1.height;
Integer o2Square = o2.width * o2.height;
return o2Square.compareTo(o1Square);
}
});
List<Rectangle> finalRects = new ArrayList<Rectangle>();
mainloop:
for(Rectangle rect: allRects) {
for(Rectangle finalRect: finalRects) {
if(finalRect.contains(rect)) {
continue mainloop;
}
}
finalRects.add(rect);
}
for(Rectangle rect: finalRects) {
PolygonShape polyShape = new PolygonShape();
polyShape.setAsBox((float)rect.getWidth() / 2, (float)rect.getHeight() / 2, Vector2.tmp.set((float)rect.getCenterX(), (float)rect.getCenterY()), 0f);
mapBody.createFixture(polyShape, 1);
polyShape.dispose();
}
}
however this sill seems pretty inefficient because for some reasons its still creating smaller fixtures than it could be possible, for example in upper right corner
also its creating single fixtures in the corners of the center rectangle and I can't figure out why!
Is the whole idea all inefficient, and should I use other method or manually create collision maps or what could be the best idea?
Originally each tile was its own fixture which caused weird bugs on their edges as expected
First off, a custom tile mapping tool is a great idea on the surface, but you're reinventing the wheel.
libGDX has built-in support for TMX maps.
http://libgdx.badlogicgames.com/nightlies/docs/api/com/badlogic/gdx/maps/tiled/TmxMapLoader.html
Instead of using your homebrew editor, you can use a full featured editor such as this Tiled - http://www.mapeditor.org/
So once you have a better system in place for your maps, I would look at this from an object oriented perspective. Since you want to use box2d physics, each collidableTile HAS A body. So all you need to do is assign a physics body to each collidableTile, and set the size according to your standard tile size.
Don't forget that there is a difference between the box2d world and your game screen, where box2d is measured in metric units, and your screen is measured in pixels. So you need to do some math to set positions and size properly. If you want a set of tiles to share a body, you may want to pass in the body as a parameter when you construct each collidableTile, and then adjust the size of the body based on how many adjacent tiles you can find. More complex shapes for the physics body may be more complex.
You can also save resources by setting those tiles to 'sleep', where box2d does a reduced simulation on those bodies until it detects a collision. If you're only using box2d for collision detection on terrain, you may want to consider other options, like using shape libraries to detect intersections, and then setting the box2d physics on your player characters body to stop downward acceleration while there is contact, or something.
Im trying to get a rectangle to move from a fixed location, to a click point in my game. I have it working to the point that im getting good coordinates from the e.getX and e.getY methods in the mouse listener class. I also have the rectangle moving in straight lines to the side or up and down by increasing and decreasing the positionX and Y values but i need a way to move it to any point that i click on, basically i need to set the change in x and y. The way i was thinking is to compute the rise and run of the line from the click points and the start point and then set the x and y values to the rise and run. If i do it this way, i need a way to decrease the rise and run values down to their lowest terms so it moves fluidly. Or if there is a way im not thinking of that you can offer any guidence that would be helpfull.
How are you drawing it at the moment? Below is a method I used to shoot bullets in a little game that I made/really should finish sometime.
This is by no means all the code you will need, and in some places there are better ways to do things (which I'm sure people will start to tell me in the comments section after :) ) but it should give you a basis to work from.
The one thing missing from this is regulating the speed at which it repaints (fps), sorry but I can't remember the simple way to do this right now (need to get back to my actual job!) Hope it helps.
The barebones of it will be something like this:
//these set out the current position of your rectangle
double recX, reYy, recH, recW;
//this gives something to manage speed
int speed;
public void paintComponent(Graphics g) {
g.drawRectangle(recX,rexY,recH,recW);
}
//here we work out the movement
public void clickedScreen(double x, double y){
double newX = x;
double newY = y;
//calculate the speed to move at
vX = newX - recX;
vY = newY - recY;
//get the distance
length = Math.sqrt((v1*v1)+(v2*v2));
//make it a unit vector
v1 = v1/length;
v2 = v2/length;
}
public moveRec(){
recX = recX+(v1*speed);
recY = recY+(v2*speed);
}
while(true) {
moveRec();
repaint();
}