I am trying to move a sprite to the mouse position on click.
However, the coordinates I am getting from Gdx.input.getX()and Gdx.input.getY() is relative to the top left corner, and the setPosition() method of Sprite is relative to the bottom left corner.
Why is this so, and how do I position my sprite where the mouse was clicked?
Screen coordinates come from Android and use a Y-down frame of reference. Cameras in libgdx by default use a Y-up frame of reference (because OpenGL by convention also uses a Y-up frame of reference).
If you prefer the Y-down frame of reference, you can use camera.setToOrtho(true); method to flip it upside down. You might prefer this if coming from a Flash background.
But in general, the safe way to translate screen coordinates from a touch into the camera's coordinate system is to do the following. This will work regardless of what platform you're on and whatever coordinate system you chose for the camera. For example, for some types of games, you wouldn't even be using a camera that matches the screen resolution, but you'd still want screen coordinates converted to camera coordinates. Also, if you have a camera that moves around the world, this will automatically change the touch point to world coordinates.
tempVector3.set(Gdx.input.getX(), Gdx.input.getY(), 0);
camera.unproject(tempVector3);
//now tempVector3 contains the touch point in camera coordinates.
It uses Vector3 because this also works for 3D cameras.
Related
Like everyone else, I'm having trouble following how libgdx's coordinate transformations. I'm creating a scrabble-like game, and dragging a finger on the screen pans the camera. The tiles are Actors on a Stage, and I'm doing the camera transformations on the stage's camera. That all works. Now I'm trying to give it a fancy background for the tiles to sit on. I can't quite figure out the draw method to make it work.
//Assets class
static final Texture feltBackground = new Texture(
Gdx.files.internal("felt_background.png"));
feltBackground.setWrap(Texture.TextureWrap.Repeat,
Texture.TextureWrap.Repeat);
//board rendering snippet
private void drawBackground() {
batch.setProjectionMatrix(board.getCamera().combined);
batch.begin();
screenUpperLeft.set(0, 0, 0);
screenLowerRight.set(Gdx.graphics.getWidth(),
Gdx.graphics.getHeight(), 0);
board.getCamera().unproject(screenUpperLeft);
board.getCamera().unproject(screenLowerRight);
batch.draw(Assets.feltBackground,
0, 0,
(int)screenUpperLeft.x, (int)screenUpperLeft.y,
(int)screenLowerRight.x, (int)screenLowerRight.y);
batch.end();
}
What I'm attempting in drawBackground is:
set boundary points to screen bounds
unproject those points into world space to find the region of the texture I should draw
draw that region to the screen origin
However, with the code like this I'm having various weird problems like the lower boundary of the background region starting offscreen, the upper boundary moving when the camera is zoomed, the texture panning faster than my finger's movement (although the boundaries of the background region pan correctly), the y axis pans mirrored, etc. Changing the code changes these symptoms, but I haven't found a pattern to try to get closer to being correct. Any words of wisdom for drawing like this?
Edit:
Here are some screenshots to add clarity.
When I open the game, there is no background.
I can drag up, which moves up the upper boundary of the background (if there is a lower boundary, I can't ever find it)
I can drag the left boundary right, but like the bottom I can't ever find a right boundary (if it exists)
Whenever you see weird synchronization issues between your camera and the stuff you're trying to draw, it's generally a symptom of confusing world coordinates with viewpoint coordinates (or vise versa) somewhere in your code.
You're using a SpriteBatch to do the rendering, right? When I look up the API for the version of SpriteBatch#draw() which you are calling, it says that those first two floats are the position that you're rendering the sprite in the world, and the four integers have to do with the source and height of the source image.
When you pass (0,0) as the position, it is drawing the image at 0,0 in your game world, which is not (0,0) on your viewport.
I would recommend a simpler approach- instead of trying to project or unproject the coordinates, set the draw location (those first two floats) to stage.getCamera().position.x and stage.getCamera().position.y.
I'm doing a platformer game using cocos2d-x v3 in c++, where the maps are usually very large, the visible screen follows the object through the map but I can't find a way to get the position of the visible screen in the map.
Using Size visibleSize = Director::getInstance()->getVisibleSize();gives me the dimensions of the entire map.
Let's say I want to show a sprite in the top right corner os the screen whenever the object reaches a point in the map, and this sprite would be always in the top right corner os the screen.
Using the object position doesn't do it.
Is there a way to get the position of the current screen?
Or is there a way to show a sprite or whatever in the screen and it would be in the screen even when the screen is moving?
Ps. I'm super noob in game development
There is a simple resolution:
You need two layer:
1: gamelayer
2: uilayer
Gamelayer is the one which you can move.Your map is added on gamelayer and when you need move the map you can just move the gamelayer.
Uilayer doesnt't move and its zorder is larger than the gamelayer.The sprite that shuold be always in the top right corner of the screen is on this layer.
Also:
There is a more complicated way：
You doesn't need to move the gamelayer.Just bind a camera to gamelayer and bind another camera to uilayer.
When you need to see the rest of your big map,you just move the camera of the gamelayer where you want.
BTW:
This is my first answer on stackoverflow.
English is not my first language,not very fluent.
Hope this can help you :)
I answered this question for you, which is a duplicate of the current question. The exact same solution applies to both situations. Add your sprite to the HudLayer as described in this question.
In Cocos2d-x's sample code cpp-tests, there is a UIVideoPlayer sample in android platform.
I change the video's position to (0,0) and even add a layer(or a sprite) overlapped on it, the video just can't be covered any way(video playing is fine), even the FPS and the vertex count info are the same.
Is it normal? Nothing can overlaps the video? If not, how can I overlap my sprite(or layer) on it?
By default, all non-cocos2d views are on top of everything drawn by cocos2d.
You can only add the video in the background, with cocos2d drawing everything on top.
What you can not do is to have a cocos2d node drawn in the background, draw the video over it, then draw another cocos2d node on top of the video. The reason is simple: cocos2d draws everything to its own view, and there's only one cocos2d view. So you can only change the draw order of everything drawn by cocos2d with some other view, since nodes aren't views themselves.
Question: How do you drag an object in a 3d environment with libgdx?
I manage to pick the object by using a Ray projected from the screen point that I touch and checking if intersects the object's bounding box but I don't understand how to actually update its position. What I'm trying to achieve is a movement on the xz plane, so that when I drag my finger towards the upper ( or lower) end of the screen, the objects move in depth on the plane. Anybody can help?
Hi to keep it short and simple let's say I have a stage with 400x400 size in pixels, but I've drawn a map of 1000x1000 size in pixels. I want my player to be able to "walk" about the stage, but it appears stage.x and stage.y are read-only? Is there any method or way to have the stage "scroll" about, without having to move each object on the map?
Don't move the stage, move the 1000x1000 object,then it'll look like the whole thing is moving.
You should see the stage like a window. You can see everything behind it depending on the size of the window. You cannot change the size of the stage, or move it.
Just like a window you can measure the size of the stage. You can use this to navigate for example movieclips across the stage with actionscript.
Why don't you put the map and the other objects in a seperate layer, and move the map around. Other objects (for example a big red dot to tell the user its' location on the map) are on a fixed position on the map. Just move the map following a sort of path according the red dot.
Not entirely sure what you want to do, but it isn't possible to move the stage.
You can put all the movieclips (the player and the map, if you want) in one movieclip, put only that movieclip on the stage and move that.
But if you only want the map to scroll, just move the map around.
The other answers are correct, but there's an alternative to moving the map:
ScrollRect
Attach a rectangle to a your map's scrollRect property. Moving that rectangle will have the same apparent effect as moving the stage around.
There are minor pros and cons to using scrollRect vs. moving the world, but try them both and see which works better for you.