ReadPixels on a specific area of the screen with NGUI

Unity Engine
1

Hi,

I’m having huge problems getting to take a screenshot of a particular part of the screen. I’ve tried several things but none of them seem to work. I’m using NGUI to build my GUI and the part of the screen i’m trying to take a screenshot off is part of a UITexture with several other textures.
The screenshot function is working but it always starts at the wrong coordinates.

Here’s my code:

banknote.worldCorners[0] is the bottomLeft point of the texture
banknote.worldCorners[1] is the topLeft point of the texture

public class TakeScreenShot : MonoBehaviour
{
    //The banknote UITexture
    public UITexture banknote;

    //Camera used by NGUI
    public UICamera cam;

    //The rect with the size and coordinates of the banknote
    private Rect texRect;

    private IEnumerator ScreenShot()
    {
        Debug.Log ("Grabbing texture!");

        Texture2D tex = new Texture2D((int) texRect.width, (int) texRect.height, TextureFormat.RGB24, false);
        yield return new WaitForEndOfFrame();

        tex.ReadPixels(texRect, 0, 0);

        tex.Apply();

        Destroy(tex);
        byte[] bytes = tex.EncodeToPNG();
      
        File.WriteAllBytes(Application.persistentDataPath + "/Banknote.png", bytes);
        StartCoroutine(ScreenshotManager.SaveExisting( bytes, "banknote"));
    }

    public void CaptureImage()
    {
        //Set the right coordinates for the picture
        Vector3 NoteBottomRight = cam.camera.WorldToScreenPoint(banknote.worldCorners[3]);
        Vector3 NoteTopLeft = cam.camera.WorldToScreenPoint(banknote.worldCorners[1]);

        int width     = (int) (NoteBottomRight.x - NoteTopLeft.x);
        int height    = (int) (NoteTopLeft.y - NoteBottomRight.y);

        float x = banknote.worldCorners[0].x;    //Left side of the banknote
        float y = banknote.worldCorners[1].y;    //Top Y of the banknote

        Debug.Log ("Starting capturing image:\n x: " + x + "\n y: " + y + "\n width: " + width + "\n height: " + height);

        texRect = new Rect(x, y, width, height);

        Debug.Log (texRect);

        StartCoroutine("ScreenShot");
    }
}

I’m trying to take a screenshot of the following item (whole banknote):

And the result:

As you can see the size is about right, but the pixel coordinates are way off. Any idea how to fix this?

I forgot to mention, i’ve created some simple primitives (cubes) to check if the positions are right. And when I create a primitive at banknote.worldCorners[0] it is positioned at the bottom left corner of the banknote. Same goes for banknote.worldCorners[1] the cube is then positioned at the top left corner of the banknote.

2

Anyone?

3

And again, I still need help with this problem!

4

Bounds imgBounds = NGUIMath.CalculateAbsoluteWidgetBounds(img.transform);
Vector3 tlPoint = UICamera.currentCamera.WorldToScreenPoint(imgBounds.min);
Vector3 brPoint = UICamera.currentCamera.WorldToScreenPoint(imgBounds.max);
int w = (int)(brPoint.x - tlPoint.x);
int h = (int)(brPoint.y - tlPoint.y);
Rect rect = new Rect(tlPoint.x, tlPoint.y, w, h);

img is a Widget
ReadPixels by rect