Unity Sprite Merging - Takes children Sprite Renderers, Merges them into a single parent

SpriteMerger.cs

using System.Collections;
using System.Collections.Generic;
using Sirenix.OdinInspector;
using UnityEngine;

[RequireComponent(typeof(SpriteRenderer))]
public class SpriteMerger : MonoBehaviour
{
    private const int PixelsPerUnit = 256;
    
    [Button]
    public void Combine()
    {
        // Calculate the bounds of all child sprites
        Rect totalBounds = GetTotalBounds();
        
        // Create a combined texture
        Texture2D combinedTexture = CreateCombinedTexture(totalBounds);
        
        // Trim the combined texture
        combinedTexture = TrimTexture(combinedTexture);

        // Create the final sprite
        CreateFinalSprite(combinedTexture);
    }

    private Rect GetTotalBounds()
    {
        SpriteRenderer[] childSprites = GetComponentsInChildren<SpriteRenderer>();

        float minX = float.MaxValue, minY = float.MaxValue, maxX = float.MinValue, maxY = float.MinValue;

        foreach (SpriteRenderer childSprite in childSprites)
        {
            if (childSprite.gameObject != this.gameObject)
            {
                Vector2 spriteSize = childSprite.sprite.bounds.size;
                Vector2 localPosition = childSprite.transform.localPosition;

                minX = Mathf.Min(minX, localPosition.x);
                minY = Mathf.Min(minY, localPosition.y);
                maxX = Mathf.Max(maxX, localPosition.x + spriteSize.x);
                maxY = Mathf.Max(maxY, localPosition.y + spriteSize.y);
            }
        }

        Vector2 min = new Vector2(minX, minY);
        Vector2 size = new Vector2(maxX - minX, maxY - minY);

        return new Rect(min, size);
    }


    private Texture2D CreateCombinedTexture(Rect totalBounds)
    {
        // Convert bounds size to pixel size
        Vector2Int totalSize = new Vector2Int(
            Mathf.CeilToInt(totalBounds.width * PixelsPerUnit),
            Mathf.CeilToInt(totalBounds.height * PixelsPerUnit)
        );

        // Create a new texture with the calculated size
        Texture2D combinedTexture = new Texture2D(totalSize.x, totalSize.y, TextureFormat.RGBA32, false);
        combinedTexture.filterMode = FilterMode.Point;

        // Initialize all pixels to be fully transparent
        for (int x = 0; x < combinedTexture.width; x++)
        {
            for (int y = 0; y < combinedTexture.height; y++)
            {
                combinedTexture.SetPixel(x, y, new Color(0, 0, 0, 0));
            }
        }

        // Go through all child sprites and draw them onto the new texture
        SpriteRenderer[] childSprites = GetComponentsInChildren<SpriteRenderer>();
        foreach (SpriteRenderer childSprite in childSprites)
        {
            if (childSprite.gameObject != this.gameObject)
            {
                // Position is local to the parent transform
                Vector2 localPosition = childSprite.transform.localPosition;
                AddSpriteToTexture(localPosition, childSprite.sprite, totalBounds, combinedTexture);
                childSprite.gameObject.SetActive(false);
            }
        }

        combinedTexture.Apply();
        return combinedTexture;
    }


    private void AddSpriteToTexture(Vector2 position, Sprite sprite, Rect totalBounds, Texture2D combinedTexture)
    {
        Texture2D spriteTexture = sprite.texture;
        Vector2Int pixelPos = WorldToPixelCoordinates(position, totalBounds);

        for (int x = 0; x < spriteTexture.width; x++)
        {
            for (int y = 0; y < spriteTexture.height; y++)
            {
                Color pixelColor = spriteTexture.GetPixel(x, y);
                if (pixelColor.a > 0) // Don't overwrite pixels if the current pixel is transparent
                {
                    combinedTexture.SetPixel(pixelPos.x + x, pixelPos.y + y, pixelColor);
                }
            }
        }
    }

    private Vector2Int WorldToPixelCoordinates(Vector2 worldPos, Rect totalBounds)
    {
        return new Vector2Int(
            Mathf.FloorToInt((worldPos.x - totalBounds.xMin) * PixelsPerUnit),
            Mathf.FloorToInt((worldPos.y - totalBounds.yMin) * PixelsPerUnit)
        );
    }

    private Texture2D TrimTexture(Texture2D original)
    {
        int xMin = int.MaxValue, xMax = int.MinValue, yMin = int.MaxValue, yMax = int.MinValue;

        for (int x = 0; x < original.width; ++x)
        {
            for (int y = 0; y < original.height; ++y)
            {
                Color pixelColor = original.GetPixel(x, y);
                if (pixelColor.a > 0)
                {
                    if (x < xMin) xMin = x;
                    if (x > xMax) xMax = x;
                    if (y < yMin) yMin = y;
                    if (y > yMax) yMax = y;
                }
            }
        }

        int width = xMax - xMin + 1;
        int height = yMax - yMin + 1;
        Color[] pixels = original.GetPixels(xMin, yMin, width, height);

        Texture2D trimmedTexture = new Texture2D(width, height);
        trimmedTexture.SetPixels(pixels);
        trimmedTexture.Apply();

        return trimmedTexture;
    }

    private void CreateFinalSprite(Texture2D combinedTexture)
    {
        Sprite finalSprite = Sprite.Create(combinedTexture, new Rect(0.0f, 0.0f, combinedTexture.width, combinedTexture.height), new Vector2(0.5f, 0.5f), PixelsPerUnit);
        SpriteRenderer renderer = GetComponent<SpriteRenderer>();
        renderer.sprite = finalSprite;
    }
}

Hello!
Apologies for commenting on an unrelated gist but a while ago I've commented on your SLayoutGroup gist with a question about its licence because I wanted to know if it's ok if I use it in a commercial project. However, you hid or deleted that gist right after. Was there any problem with the licensing of that code? Could you please let me know? I have my email address public on my profile. Thanks in advance!

Hey, The code was a modified version of Unity's layout group. Because Unity's terms are pretty strict, I thought it best just to remove the gist, despite everyone having access to the original, and it only being operable in Unity. If it was just my code, I would share it freely.

…

On Tue., Jan. 7, 2025, 5:43 p.m. Wiktor Aaron Wąsowski, < ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Hello! Apologies for commenting on an unrelated gist but a while ago I've commented on your SLayoutGroup gist with a question about its licence because I wanted to know if it's ok if I use it in a commercial project. However, you hid or deleted that gist right after. Was there any problem with the licensing of that code? Could you please let me know? I have my email address public on my profile. Thanks in advance! — Reply to this email directly, view it on GitHub <https://gist.github.com/codorizzi/bf544229f76266c9df0b723a1e83a152#gistcomment-5377146> or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACUV6NIYQG4R66DEV5KDA432JPYYZBFKMF2HI4TJMJ2XIZLTSKBKK5TBNR2WLJDUOJ2WLJDOMFWWLO3UNBZGKYLEL5YGC4TUNFRWS4DBNZ2F6YLDORUXM2LUPGBKK5TBNR2WLJDHNFZXJJDOMFWWLK3UNBZGKYLEL52HS4DFVRZXKYTKMVRXIX3UPFYGLK2HNFZXIQ3PNVWWK3TUUZ2G64DJMNZZDAVEOR4XAZNEM5UXG5FFOZQWY5LFVEYTEMZRGE2DONZQU52HE2LHM5SXFJTDOJSWC5DF> . You are receiving this email because you authored the thread. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub> .

Ok, thank you for clarification!