So I am super stoked to start using LibGDX for my first android title for OUYA and PC, but I am running into some snags with LibGDX. (All of my questions can be answered by looking at source, but I am really trying to understand the design choices as well).
To start with, the coordinate system. I created a project using the Project Setup jar, and it creates an OrthographicCamera like so
camera = new OrthographicCamera(1, h/w);
From my reading, I understand that LibGdx uses bottom left corner for 0,0 and yUp. Fine.
I see that it is pretty easy to change to y down if I want to, but I am not understanding the next bit of code that was created.
For the default sprite that gets created the position is set like so.
logoSprite.setOrigin(logoSprite.getWidth()/2, logoSprite.getHeight()/2);
logoSprite.setPosition(-logoSprite.getWidth()/2, -logoSprite.getHeight()/2);
When I run this basic program, I see the logo image I have added is centered on the screen. What I am trying to understand is why the values are negative in set position, and why is it using the sprite width and height instead of the graphics w and h of the view port? If I change to the screen width and height, then the image is drawn in some odd position in the lower right hand side of the screen.
My next question is sprite.setSize vs sprite.setScale. Why is the difference between the two? (They appear to do the same thing, except setScale leaves getWidth and getHeight unchanged).
Since my game will be using a 2D camera heavily for panning, zooming and rotation, I am trying to understand as much as I can about the libgdx framework before I start writing any code.
As a side note, I have a game development and math background and I have made several 2D and 3D games using XNA. I am finding LibGdx a bit frustrating as it does not abstract away OpenGL as much as I was expecting it to, and so far the 2D drawing I have been experimenting with seems to be more confusing than it should be!
I also wanted to note that I am planning to use spine for my animations. Should that change my choice to use y-up or y-down?
If you want to draw a sprite in center of screen, do this in your create method
logosprite.setposition(scrw/2-logosprite.getwidth()/2,scrh/2-logosprite.getheight/2);
here scrw is your viewport's width,
and scrh is your viewport's height,
this way your sprite will be in center of screen
sprite.setsize is used for setting size of the sprite and sprite.setscale is used when we scale a large/small texture so that its quality remains good in all devices(hdpi.mdpi,xhdpi,ldpi)..
no need to worry if you are using spine it works smoothly in libgdx..
You can use just this code if possible
logoSprite.setPosition(Gdx.graphics.getWidth()/2 - image.getWidth()/2,
Gdx.graphics.getHeight()/2 - image.getHeight()/2);
To center the sprite into the middle of the screen Where "image" is the Texture you have loaded/declared initially.
As for why it is coming in a odd position is due to the fact that you are using a camera.
Which changes the view a lot just go through the documentations of libgdx about camera here
In my case, I needed to set position of camera and then call update() method.
Then never forget camera's (0,0) is its center. Everything is being placed that way. My camera code:
private void cameralariUpdateEt() {
cameraGame.position.set(cameraGame.viewportWidth * 0.5f,
cameraGame.viewportHeight * 0.5f, 0);
cameraGame.update();
cameraScore.position.set(cameraScore.viewportWidth * 0.5f,
cameraScore.viewportHeight * 0.5f, 0);
cameraScore.update();
}
Call this method from inside render();
Step 1: Set the sprite origin to the position you would like it to rotate around.
// camera center point is (c.x, c.y)
logoSprite.setOrigin(c.x, c.y);
Step 2: make sure to set your sprite center to origin
logoSprite.setOriginCenter();
Step 3: Rotate your sprite
logoSprite.setRotation(Angle);
Step 4: Set the sprite position, [subtract half the sprites width and height to center the sprite]
logoSprite.setPosition(c.x - logoSprite.getWidth() / 2, c.y - logoSprite.getHeight() / 2)
Related
I've some problem for render Box2D Debug with Box2DDebugRenderer.
I've 2 OrthographicCamera, one for render the world (named Cam) and one for the HUD (healthBar, Armor, ...) (named hudCam).
I've tried to render :
b2dr.render(world, cam.combined); -> I can't see the Box2D
b2dr.render(world, cam.projection);
b2dr.render(world, hudCam.combined);
b2dr.render(world, hudCam.projection);
b2dr.render(world, new OrthographicCamera().combined); and b2dr.render(world, new OrthographicCamera().projection)
I can't find a way to render the Box2D exactly like cam, to see the edge of all bodies.
If somebody understand my problem, please help me !
Thx.
Unfortunately some tutorial out there suggest to use a meter-to-pixel-conversion when using Box2D. This is not neccessary (at least with Libgdx), as this conversion can be done by using a camera.
The problem in your case is, that you are using a meter-to-pixel-conversion when rendering the Sprites, while the Box2DDebugRenderer renders everything 1:1.
To solve this problem you have to get rid of the meter-to-pixel conversion and use the camera or the viewport to "scale" the things.
THis way, the Box2DDebugRenderer and your SpriteBatch can (and should) use the same camera to render.
For the camera/viewport:
The constructor has the params width and height. Those params are often set as Gdx.graphics.getWidth() and Gdx.graphics.getHeight(), which in my optinion is not right, the game should be resolution-independent.
You should instead select those values depending on how big your player (or any other visible entity) is in real life and how big it should be on screen.
Let's say you have a little characte, like in your game. It is 1m tall in real live and should take 1/13 of the screen height (more or less like in your first picture, where the screen is about 13 times as high as the character).
So your cameras height should be 13, your characters height (also it's Box2Ds Body height) should be 1m. Next you need to define the width. For that i like to think about my desired aspect ratio. Lets assume the game should focus on 16/9 devices, the width is then (13/9)*16=23.
Now your camera should be created like this:
camera = new OrthographicCamera(23, 13);
I am working on a flash sound mixer application with multiple sound channels, and I am having trouble with the lights beside the volume knob.
Is there a way to hide just a part of an image?
On the image below, image-2 is on top of image-1 to create some kind of volume level indicator effect, and how much of image-2 is shown depends on the value of the volume.
image-url: http://s30.postimg.org/r3ow1g5bl/volume_lights_level.png
I've tried by just reducing the height of image-2, but it looks awful and distorted.
Is there something in flash that works closely the same as CSS's behavior.
example: I'll just make image-2 a background of a shape, and when I reduce the shape's height, the image-background does not get distorted or changes it's height as well.
By searching for solutions, I have come across the mask property, but I don't quite understand how it works, and most of the examples shown are images placed inside circles.
Is the mask property applicable in this situation?
I'm quite new to flash so I don't know a lot of things yet.
You can indeed use a mask.
How to programmatically create your mask
Put an occurrence of your image named myImage on the stage, and put over this occurrence a mask named myMask with the same dimensions. You can apply myMask mask to myImage using it's mask property like below:
Main Timeline
myImage.mask = myMask;
function mouseMoveHandler(e:MouseEvent):void {
myMask.height = myImage.y - e.stageY;
}
stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
You have just to adapt this code to your animation, in the function where you click your button.
I got it working now, many THANKS #VC.One. heres how I did it.
Imported img-2 to stage, converted it into symbol(type:Movie Clip), assigned instance name: img2_mc.
I created a new layer for the mask, drawn a rectangle using rectangle tool, converted it also to symbol(type:Movie Clip), assigned instance name: mask_mc.
Then applied the mask to img2_mc.
/* the code */
img2_mc.mask = mask_mc;
function onEnterFrame(event:Event):void{
var volumeKnob_y = volSliderKnobOn.y + 12; // adjust it to the center of the knob
mask_mc.height = volumeKnob_y;
}
I am making a game in cocos2dx(c++).Here i have to make dynamic sprites that are falling top to down and on touch i have to kill them.I mean the sprites are of insects and they will be killed on touch
The problem is that I am unable to get the idea on how to implement them as on increasing the level the insects will be falling more and with more speed.
I have made for one insect.But don't know how to handle for multiple insects
Suppose, your 1st Sprite is coming from y height and it fell to -y/2 with a velocity of 10.
Then, you have to make several sprites with differnt velocities and different positions of x.
You can move a sprite in cocos2dx with the help CCMoveTo()
You can use this custome method to move sprite
void GameLayer::_mov(CCSprite *cp, float x, float y)
{
cp->setPositionX(cp->getPositionX()-x);
cp->setPositionY(cp->getPositionY()-y);
}
In this method we passing sprite which we have to move and x is how much change in sprite position and y is how much change in sprite position. In this I subtract x and y from the current position of sprite but you can add also according to your requirement.
You have to call this method in your update method.
I have a spritesheet (packed by the wonderful TexturePacker) that looks like so:
and the animation as an animation works well using the current code.
However, when the animation moves to a frame where the bounding box is smaller (e.g. when the legs are closer, when the figure is kneeling, etc.), the image distorts so that the smaller bounding box fills the bounding box of the sprite.
How can I fix this?
The spritesheet above is a frame-extraction from a sample Adobe flash animation.
Easier way:
You can make all the textureregions the same size.
Hard way:
Keep it like this, but you need to save and calculate the size and position of every textureregion to draw.
I personally recommend you the first option, just make all the image the same size.
cant give you a link but here is what i do for these situations
while making the texture packer strip the white space
make a array of AtlasSprite for images
then in my render method
public void render(float delta) {
atlasSprite = animation.getKeyFrame(statetime, Animation.LOOPING);
atlasSprite.draw(batcher)
};
in my update method, which gives exact rectangular bounds of the current image displayed. Since you have stripped the whitespace and used AtlasSprite so bounds will be without blank whitespace.
public void update(float delta) {
bounds = sprite.getBoundingRectangle();
}
P.S. this is just a pseudo code and many syntatical error could be there its just to give you a idea
I have a bit problem with rotationX and rotationY.
It's cool if i just do a roationX and rotaionY below
_eventParent.rotationY =_differentX;
_eventParent.rotationX =_differentY;
However once i have assign a mouse move to the _eventParent. The roationX and roationY change perspectively while the mouse is moving. so instead the item remain the same size. it increase and decrease size prospectively. any idea why is it doing this? is there a possibility to stop this behavior?
Thanks
Please find the image below.
Perspective allows part of your shape to look closer to you than other parts. The problem is that perspective has a center, or "vanishing point" and by default, it is fixed. As you move your shape farther away from the vanishing point, the perspective changes, causing your shape to widen or narrow.
You can fix this by updating the vanishing point so that it is always at the same coordinates as your shape. Since the shape will always be at the vanishing point, the perspective shouldn't change.
To do this, create a perspectiveProjection for your shape:
_eventParent.transform.perspectiveProjection = new PerspectiveProjection();
PerspectiveProjection is located in the flash.geom package, so don't forget to import it.
Then whenever you update your shape's position, update it's vanishing point:
_eventParent.transform.perspectiveProjection.projectionCenter =
new Point(_eventParent.x, _eventParent.y);
You might need to offset the vanishing point by a set number of pixels to get the perspective looking the way you want it to.
Correct me if I misunderstood your question. Your question is that if you apply rotation to the movieClip object, then why does the size appear to be changing?
For simplification, Let's not apply rotation on both X and Y axis. Let's take a rectangular movie clip and onMouseMove we do ++myMovieClip.rotationX;
Now, this statement is going to apply rotation on the object about the X-axis and one would get a perspective of the movie clip flipping across X -axis and this flipping will show as change in size of the object.
The same applies to rotating across y-axis.