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Parallax effect for background [C#] just a simple math error but I can't fix it
I've been trying to solve this problem on my own for a couple hours and I can't seem to figure it out, so I thought I'd ask it here.
I have three background layers (with layer3 being the farthest) and I want them to scroll depending on where you are in the level. (e.g. when in the exact center they all are centered, on the left their left edges match the left side of the screen, etc.)
However, instead they all start perfectly centered with the camera, when they should have their left edges aligned with the left side of the screen. (the camera is at it's farthest left position at the beginning)
Then, as the camera moves, they move super fast, like in the screenshots provided.
This is about ten units into the level and you can already see their edges. 
Then at just over halfway through the level, they are way offscreen. (They should be about centered here.)
How can I edit my math to make it work correctly?
Code
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class BackgroundHandler : MonoBehaviour {
float lC, rC, tC, bC, hDist, vDist, hMid, vMid, hSpan, vSpan;
float sprSize;
SpriteRenderer rend;
Transform cam;
void Start () {
rend = GetComponent<SpriteRenderer>();
cam = GameObject.Find("Main Camera").transform;
if (rend.sprite.name == "layer3")
{
sprSize = 2;
}
if (rend.sprite.name == "layer2")
{
sprSize = 3;
}
if (rend.sprite.name == "layer1")
{
sprSize = 4;
}
lC = GameObject.Find("PConstLeft").transform.position.x + 6.5f;
rC = GameObject.Find("PConstRight").transform.position.x - 6.5f;
tC = GameObject.Find("PConstUp").transform.position.y - 5f;
bC = GameObject.Find("PConstDown").transform.position.y + 5f;
hSpan = rC - lC;
vSpan = tC - bC;
hMid = lC + (hSpan / 2);
vMid = bC + (vSpan / 2);
}
void Update () {
hDist = -(hMid - cam.position.x);
vDist = -(vMid - cam.position.y);
transform.position = new Vector2(
(hMid + lC + hDist) * sprSize,
(vMid + bC + vDist) * sprSize
);
}
}
Explanation:
lC, rC, bC, and`tC` are the extents of the camera movement, left, right, bottom and top.hDist and vDist are the horizontal and vertical distances of the camera and middle of the scene.hMid and vMid are the midpoints of the constraints. hSpan and vSpan are the total distance from constraint to constraint. sprSize is the size (in screens) of the background image.
If anyone can help with my faulty math or has any clarifying questions please let me know!
@SoshJam you don't ask a question. i.e. why is the math wrong? What do you get when you run this code? $$anonymous$$aybe some some screenshots would help as well.
I think the problem may be with your "sprSize", try a lower value such as 0.2f ins$$anonymous$$d of 2
And layer 1 should have a lower value that layer 3.
Still lots of info missing, plus you seem to be using sprSize, which you say is the "size of number of background screens", in lieu of "speed" (because it seems to me that you should be using speed at that point). Of course, speed should be higher for the front layers, which correspond to larger size, but I suspect that by using size the way you do, makes it difficult to adjust the layer speed to good values.
To be able to provide more help, I'd like to know the transform.position of all you constraints and camera (starting pos). Still, better than that, would be to upload (in OneDrive or something) a repro project, which I could take a look directly.
I fixed it on my own. What I did was calculate how far in percent the player was to the end of the level, and factored that in to the screen bounds and sprSize. It works.
