I am currently creating a game based on a platform that tilts side to side and there is a ball on that platform. For this ball I applied dynamic body physics and got it to work great, but when I try updating the ball's sprite rotation based on the ball's body angle the sprite will not rotate.
My code is below.
public static void update(float delta) {
delta *= 0.7;
world.step(delta, 10, 4);
//Angular Impulse is here to test if ball sprite is rotating
ballBody.applyAngularImpulse(40, true);
AssetManager.ballSprite.setRotation(ballBody.getAngle());
AssetManager.ballSprite.setPosition(ballBody.getPosition().x,
ballBody.getPosition().y);
}
}
Whenever you want to rotate a sprite in libgdx when rendering it you must do:
sprite.draw(spritebatch);
but I made the mistake of trying to render it how I would render anything else:
spritebatch.draw(sprite);
Related
I've got a problem to draw a sprite to my project.
I have a map (960x900) divided into tiles (64x64).
As you can see in the picture, when i click on the bottom left corner of the purple square, the position is (0;0), and when I click on the top right corner of purple square, the position is (36;47)
The problem is that the picture of the purple square has a size of 32x32, and when I draw this picture with libgdx on the screen, the size doesn't match.
Another example: the square with black border has a size of 64x64. So if I draw the purple square in front of the black, the purple should be the half (in height and in width) of the black, no?
Does anyone know why libgdx resizes the purple square?
Sprite sprite = new Sprite(new Texture("assets/purpleSquare.png"));
i draw it in a method
public void render(SpriteBatch batch) {
batch.draw(sprite, 0, 0);
}
I don't know why the picture is resized by libgdx.. I have also tried to do
batch.draw(sprite, 0, 0, width, heigth);
To precise the sprite's size but it doesn't work too..
The size on screen bears no direct relation to the size of the original image. When you draw a sprite you provide the SpriteBatch with a position, width, and height in world coordinates. The sprite will be stretched to fit these world coordinates, regardless of the original image size.
When you click the screen, you are clicking in screen coordinates. The relation between screen and world coordinates is determined by the projection matrix that you use with the SpriteBatch. The projection matrix is typically controlled with a Camera or Viewport object, which you can use to convert between the two coordinate systems using the project and unproject methods.
I'm happy to see that after many hours i found a solution, even if i know which is not correct.
I would like some help to understand the problem's origin.
With this parts of code :
public void update(float delta) {
batch.begin();
drawBackground(); // Draw the background
drawButton(); // Draw the play/pause button
batch.end();
drawMap(); // draw a tmx map made with tiled
batch.begin();
if(!world.isInitial()) {
renderMonster(); // method which draw the monster
}
renderTower(); // method which draw the tower's level
batch.end();
}
I don't understand why i have to do "batch.begin()" and "batch.end()" twice.
I dont' understant why with this code, the purple square is resized.
With this code :
public void update(float delta) {
batch.begin();
drawBackground();
drawButton();
batch.end();
drawMap();
------->sb = new SpriteBatch();
sb.begin();
if(!world.isInitial()) {
renderMonster();
}
renderTower();
sb.end();
}
this line that i add fix the bug with the purple square. If i work with two SpriteBatch (because with one, if i reinitialize SpriteBatch in update method, my pause/play button diseapper) and i initialise the second (SpriteBatch sb) in the update method.
It is correct to initialise a SpriteBatch every time i'm passing on the update method ? There's no method with a SpriteBatch to avoid this problem ?
I have not found answer for this question anywhere, so let's go.
What i expect:
I want to render rocket. Rocket is flying from given start point with evaluated angle. I'm evaluating angle like this:
getVelocity().angle() - 90f
My problem is to calibrate rocket position on top of the rocket. Image below shows how should it work:
In the top picture is how libgdx render not rotated texture region. In the bottom picture is what i expect: I want to move and rotate texture region with given angle to have (x,y) coordinate on the top of rocket.
What i have:
I tired to write method to draw sprite how i expect but i failed. I think it is caused due to fact that i don't understand documentation of this method.
Following manual:
void com.badlogic.gdx.graphics.g2d.SpriteBatch.draw(TextureRegion region, float x, float y, float originX, float originY, float width, float height, float scaleX, float scaleY, float rotation)
Draws a rectangle with the bottom left corner at x,y and stretching the region to cover the given width and height. The rectangle is offset by originX, originY relative to the origin. Scale specifies the scaling factor by which the rectangle should be scaled around originX, originY. Rotation specifies the angle of counter clockwise rotation of the rectangle around originX, originY.
My code:
public static void drawRotatedTex(SpriteBatch pmRenderer, TextureRegion pmTex, float pmPosX, float pmPosY, float pmAngle)
{
pmRenderer.begin();
pmRenderer.draw(
pmTex, pmPosX, pmPosY, -pmTex.getRegionWidth()/2, pmTex.getRegionHeight(), pmTex.getRegionWidth(), pmTex.getRegionHeight(), 1f, 1f, pmAngle);
pmRenderer.end();
}
Results:
It is moment of collision. As we can see coordinates are offset in relation to rocket.
I don't ask about full solution. For me will be sufficient if someone explain me (on drawing or something) like this method works.
EDIT
Moderation suggested that this question is duplicate of:
libgdx: Rotate a texture when drawing it with spritebatch
I read this topic, but it is not my solution. I know how to rotate my sprite by i don't have idea why coordinates of rocket are offset in relation to rocket top.
EDIT
Invocation of my drawRotatedTex from rocket class:
#Override
public void render(Renderer pmRenderer, float pmX, float pmY) {
SpriteBatch lvSpritebatch = pmRenderer.getSpriteBatch();
Sprite lvSprite = null;
if(mIsExploding)
{
if((lvSprite = mExplosion.getTexture()) != null)
{
lvSpritebatch.begin();
lvSpritebatch.draw(lvSprite, pmX + lvSprite.getWidth()/2, pmY - lvSprite.getHeight()/2);
lvSpritebatch.end();
}
}
else
{
lvSprite = mAnimation.getTexture();
RendererTools.drawRotatedTex(lvSpritebatch,lvSprite,pmX,pmY,getVelocity().angle() - 90f);
}
}
It is not very clear what you are asking, if it's only about moving the origin you would not need that much text. Anyway, I will take a shot at it.
If you want to accomplish what you have in your picture you setup your sprite like this:
sprite.setOrigin(s.getWidth()/2, s.getHeight()); //Centers sprite on top of image.
If I now rotate it in the draw method it rotates around the top center.
sprite.rotate(5);
sprite.draw(batch);
Despite being rotated around the center top of itself it remains position remains the same. If I would set the origin far away from the image and rotate it then the image would travel very far but the position remains the same. Still if you would move it's position 10 pixels to the right the image (wherever it may be) will be moved to the right.
Hope this helps.
I am developing a 2d game; I am currently developing a system of movement of the camera on the map, I used the following method: my camera has own coordinates - x,y;
I have ArrayList with all my sprites for map with their coords from 0 to mapSize, every sprite has a Draw function, which looks simply like
g2d.drawImage(texture, getX(), getY(), getX() + getSizeX(), y + getSizeY(), 0, 0, getSizeX(), getSizeY(), null);
I'm always drawing all my sprites, without checking are they visible or not;
Whether there is a load on the computer at this drawing (when drawing textures that very far away from screen size)?
Do I need to check whether the object is visible before rendering?
My main DrawAll function contains():
public void DrawAll(graphics2D g2d){
g2d.translate(-playerCamera.getX(), -playerCamera.getY());
for (int i = 0; i < mapSprites.size(); i++) {
mapSprites.get(i).Draw(g2d);
}
g2d.translate(-playerCamera.getX(), -playerCamera.getY());
drawSomeStrings, etc....
}
This is not very good, because lines that were drawn after second translate may twitch when moving the screen.
Should I give translate up and do the offset coordinates manually in each object\sprite's Draw function?
graphics2D will clip your drawing. So it does not impact too much. If you have a lot of sprites, you should consider using a SpatialIndex to select which Sprite is in the screen. (https://github.com/aled/jsi)
I'm trying to make a game where the player ( the circle ) has to collect some stars. The stars will be at different positions and in order to get the stars the player must draw ramps in order to reach the stars. Picture below.
http://3w-bg.org/game/pic.PNG
The red line is where the user has drawn on the screen.
Ok so i capture the coordinates when the user touches and drags on the screen and then i use this coordinates to create a ChainShape for the line. The problem is that the line is drawn nowhere near the touched area. Picture below.
http://3w-bg.org/game/pic2.PNG
The world and the screen positions are not the same to my understanding. So how can i draw the chainshape line exactly where the user has touched. Tried camera.project/unproject but that didn't help.
Usually when using Box2D you should have some kind of pixel-to-meter ratio defined. This is done in order to keep the coordinates in your physics world smaller to keep numeric stability.
When using a Camera and a constant PIXEL_TO_METER to convert the values, you can convert your coordinates like this:
public static Vector2 screenToPhysics(Camera camera, Vector2 screenPos) {
Vector3 worldPos = camera.unproject(new Vector3(screenPos.x, screenPos.y, 0));
return new Vector2(worldPos.x, worldPos.y).scl(1f / PIXEL_TO_METER);
}
public static Vector2 physicsToScreen(Camera camera, Vector2 physicsPos) {
Vector3 worldPos = new Vector3(physicsPos.x, physicsPos.y, 0).scl(PIXEL_TO_METER);
Vector3 screenPos = camera.project(worldPos);
return new Vector2(screenPos.x, screenPos.y);
}
I am translating in my main class' render. How do I get the mouse position based on the translation?
public void render(GameContainer gc, Graphics g)
throws SlickException
{
float centerX = 800/2;
float centerY = 600/2;
g.translate(centerX, centerY);
g.translate(-player.playerX, -player.playerY);
gen.render(g);
player.render(g);
}
playerX = 800 /2 - sprite.getWidth();
playerY = 600 /2 - sprite.getHeight();
I update the player position on keydown by .2f * delta
Picture to help with explanation
i92.photobucket.com/albums/l22/occ31191/Untitled-4.png
World coordinates = camera position + mouse position
Camera position is calculated/explained in my answer to this question: Slick2D and JBox2D. How to draw
You're making a tile-based game, where each tile seems to have the same size. For this case, you don't need a generalized unprojection.
Imagine the complete map. The viewport shows only a portion of it; somewhere you need to store the (x,y) offets of the viewport into the complete map. Since the mouse coordinates are relative to the viewport, you need to add this offset to the mouse coordinates. Now, you can easily get the tile coordinates by using modulo operations on the shifted mouse coordinates with the tile's width and height.
Effectively, this is a coordinate transformation of window coordinates to tile coordinates.