CODEWITHSUNDEEP
androideclipseopengl-es
Aida E
Aida E

Reputation: 1100

Updating positions and positions outside screen

I want to show the movement of a car in a road . I have a textfile containing the positions and I built the movement by updating the position of a car every second .lets say the plain is (200,200) . now what should I do for positions that are outside this screen ? how could I follow my car there ? should I set up a camera or something? by the way my app is 2D.

Upvotes: 0

Views: 70

Answers (1)

PaulG
PaulG

Reputation: 7102

From my experience, there is no actual concept of setting up a camera in 2D programming, but I could be wrong. You'll have to do this yourself, create a camera class etc.....

What I think will end up happening is that the car will stay centered on the screen and everything under it will be moving instead. Depends on what you're trying to achieve.

So if your car is moving northeast at 20 km/h, don't actually move the car, make everything under the car move southwest at 20km/h (or how many pixels per frame this comes out to)

This is if you want to follow the car. If you want to center the "camera" on the car whenever it goes out of bounds you'll probably have to move the landscape and the car towards the center of the screen.

EDIT: I'm assuming that the car will be the main focus?? So it should always be at the center of the screen.

All objects in the game should have a velocity and a position. The position tells you where the object currently is and the velocity tells you how many x's and how many y's it should be moving per frame. So every frame you would say position = position + velocity.

The non-car objects can move off the screen as they wish without having the camera follow them, so let them go. Keep the car centered and adjust all the other objects' velocities based on the car's.

Ex:

Car's velocity (3, 0) ---> means it's moving right in the straight line at 3 pixels per frame

Object 1 velocity (4, 0) ---> means it's also moving right in a straight line but 4 pixels per frame

The velocity of object 1 will have to adjust itself according the the car's velocity. So say:

object1.position = object1.position + (object1.velocity - car.velocity)

Object 1's new velocity is (1, 0), so it's moving faster than the car by one.

If the car gains speed to let's say (5, 0) then object one will appear to be moving backwards by 1.

Upvotes: 1

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