Precise Touch Screen Dragging Issue: Trouble Aligning with the Finger due to Different Screen Resolution
- by David Dimalanta
Please, I need your help. I'm trying to make a game that will drag-n-drop a sprite/image while my finger follows precisely with the image without being offset. When I'm trying on a 900x1280 (in X [900] and Y [1280]) screen resolution of the Google Nexus 7 tablet, it follows precisely. However, if I try testing on a phone smaller than 900x1280, my finger and the image won't aligned properly and correctly except it still dragging. This is the code I used for making a sprite dragging with my finger under touchDragged():
x = ((screenX + Gdx.input.getX())/2) - (fruit.width/2);
y = ((camera_2.viewportHeight * multiplier) - ((screenY + Gdx.input.getY())/2) - (fruit.width/2));
This code above will make the finger and the image/sprite stays together in place while dragging but only works on 900x1280.
You'll be wondering there's camera_2.viewportHeight in my code. Here are for two reasons: to prevent inverted drag (e.g. when you swipe with your finger downwards, the sprite moves upward instead) and baseline for reading coordinate...I think.
Now when I'm adding another orthographic camera named camera_1 and changing its setting, I recently used it for adjusting the falling object by meter per pixel. Also, it seems effective independently for smartphones that has smaller resolution and this is what I used here:
show()
camera_1 = new OrthographicCamera();
camera_1.viewportHeight = 280; // --> I set it to a smaller view port height so that the object would fall faster, decreasing the chance of drag force.
camera_1.viewportWidth = 196; // --> Make it proportion to the original screen view size as possible.
camera_1.position.set(camera_1.viewportWidth * 0.5f, camera_1.viewportHeight * 0.5f, 0f);
camera_1.update();
touchDragged()
x = ((screenX + (camera_1.viewportWidth/Gdx.input.getX()))/2) - (fruit.width/2);
y = ((camera_1.viewportHeight * multiplier) - ((screenY + (camera_1.viewportHeight/Gdx.input.getY()))/2) - (fruit.width/2));
But the result instead of just following the image/sprite closely to my finger, it still has a space/gap between the sprite/image and the finger. It is possibly dependent on coordinates based on the screen resolution. I'm trying to drag the blueberry sprite with my finger. My expectation did not met since I want my finger and the sprite/image (blueberry) to stay close together while dragging until I release it. Here's what it looks like:
I got to figure it out how to make independent on all screen sizes by just following the image/sprite closely to my finger while dragging even on most different screen sizes instead.
