I'm using AutoParallaxBackground (from the AndEngine example) to create a background (only 20% of screen height), that appears to be moving. It works, but now I would like to add a Sprite that also moves in X direction, but isn't repeating.
The sprite should be positioned behind the background.
How can I achieve this?
I tried setting the Z index on sprites, but it isn't working, probably because the background is always the lowest.
Related
I want to use OpenGL for Android to take the screen (make "continuous" screenshots), make it smaller vertically, then paint it back to leave a black bar at the bottom of the display.
Basically:
Read pixels
Transform (shrink the screen vertically)
Paint back the shrunk screenshot on the display.
Repeat 1.-3. continuously.
How can I do this? The bottom line is that I want to have space for some other stuff at the bottom of the screen while still not missing something underneath what I want to display (think the soft home buttons in Android).
This sounds insanely expensive. I'd really try just to render it at the correct size in the first place.
Use glScissor to limit the region of the screen to stop drawing outside of that, and glViewport to correct the transform behaviour.
I am trying to move background image from upward to downward direction on cocos2d so that the fixed character sprite seem to be moving in upward direction.
Can any body tell me how to do this.
The easiest way would be to have two Sprites of screen size . move the sprite from upside to down and the give the position start of second sprite to the endposition of first sprite, this way you can have continues loop of background images.
I'm new to Android (and Java for that matter), and I'm making a simple game. I'm stuck.
My problem is this:
I have 2 png images (a background and foreground) that take up the whole screen on startup. I now want to be able to set the width of the "drawn portion" of the foreground to the x-coordinate of ON_DRAG. My control method works fine; it's used like this:
g.drawRect(0, 0, scene.getLine(), g.getHeight(), Color.GREEN);
where scene.getLine() returns the x-value of the touch. So at this point I can draw a green rectangle above my images. But what I actually want is for those rectangle dimensions to "punch a hole" in my top-layer png (so the background is revealed beneath). I do not want to scale the foreground.
I have tried clipRect, but it doesnt work because I have other images that need to be drawn on top of these two, and clipRect prevents this. I have looked at a bunch of "PorterDuffXfermode" code, but cannot understand how to apply it to my situation, and cannot make it work. i.e. I can make a Paint with the PorterDuff "SRC" mode set, but I dont know how to define "source" and "destination" images so the Paint will work its magic. A final consideration with this is that even if the PorterDuff would work, Im not sure it would be practical given that I want this thing to run at 60fps.
Any suggestions?
Thanks.
You can call canvas.save() before a clip and canvas.restore() after your drawing to return the canvas to the sate it was in before you stared. Then you can draw your additional images.
I'm working on a small app that uses sprites which are rendered using a canvas and simple drawBitmap.
Once the user touch the screen I need to know which sprite was clicked on.
I'm able to achieve this goal when I treat each sprite as a rectangular which has the width and height of the image.
However, some of the sprites takes only small portion of the entire rectangular and I would like to ignore when user clicked inside the rectangular but not on the internal shape.
Any ideas what could be a good method to do that?
Edit: Just to be more clear, lets say I have a sprite with size of 200x200, the sprite is an image of an airplane from above and the airplane has long long wings. Since the wings are long there will lots of "dead" areas in the sprite.
I would like to detect when user clicks the airplane itself only and not the "dead" area.
Thanks.
You will need to create a 2d array of all the pixels in the bitmap. Mask the pixels to either a 0(transparent) or a 1(has color). Then when you click inside of a rectangle you will just need to get the width offset and the height offset within the rectangle. This gives you your indices for mapping to the pixel array. Then check and see if the index in the pixel array contains a 1 for a value. If so then you clicked on the actual image. Does that make sense?
You have to check for the area where your Bitmap gets drawn, not another rectangular shape. Just treat every sprite (which may have different sizes) as a single rectangle, whose width and height equals to the width and height of the sprites.
Since you elaborated your question I'll give another suggestion.
When you have detected a click on the sprite, simply check (in the Bitmap's area) the current pixel via the Bitmap.getPixel() function. You can then easily check if the color at the specified position is something you're interested in, otherwise you can just skip detecting the touch.
i am trying to do this:
1) user long touches the screen,
2) a circle/ball pops up (centered around the user's finger) and grows in size as long as the user is touching the screen
3) once the user lets go of the finger, the ball (now in its final size) will bounce around.
i think i have the bouncing around figure out from the DivideAndConquer example, but i am not sure how to animate the ball's growth. i looked at various view flipper examples such as this:
http://www.inter-fuser.com/2009/08/android-animations-3d-flip.html
but it seems like view flipper is best for swapping two static pictures. i wasn't able to find a good view animator example other than the flippers. also, i would prefer to use images as opposed to just a circle. can someone point me in the right direction?
thanks.
Here are two simple tutorials to help you get started with drawing basic animations including touch input: balls bouncing randomly around the screen and basic drag and drop.
In brief: You're right, ViewFlipper is really not suited for this. You want to draw on a Canvas by making your own custom View. This is the basic framework for 2D graphics. Canvases let you draw image files, solid colors and other things to the screen, while applying transformations ot them at the same time. Handling the user input (i.e. the finger on the screen) is done via the onTouchEvent(...) method, which lets you do something when the finger touches the screen, moves on the screen or lifts off. Have a play with those two tutorials, they should give you the basics.
If you're using a bitmap on a canvas to draw it
http://developer.android.com/reference/android/graphics/Canvas.html#drawBitmap(android.graphics.Bitmap, android.graphics.Matrix, android.graphics.Paint)
Use a scale matrix, the identity multiplied by the scalar of the size you want the image to be.