Crop an UI Image with a material

Hi all!

I've a plane with a webcam stream on it (WebCamTexture). I apply a chromaKey shader to it and I copy this material to an image in my UI.

Now I would want to crop this image and take only a portion of it. I tried to mask the image but if the image has a material as in my case it doesn't work.

What can I do to crop the image?

This is the shader:

Code (CSharp):

1.  
2. Shader "Unlit/Transparent Chroma" {
3.          Properties {
4.                 _MainTex ("Base (RGB)", 2D) = "white" {}
5.                 _MaskCol ("Mask Color", Color)  = (1.0, 0.0, 0.0, 1.0)
6.                 _Sensitivity ("Threshold Sensitivity", Range(0,1)) = 0.5
7.                 _Smooth ("Smoothing", Range(0,1)) = 0.1
8.         }
9.         SubShader {
10.                 Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
11.                 LOD 100
12.                 ZTest Always Cull Back ZWrite On Lighting Off Fog { Mode off }
13.                 CGPROGRAM
14.                 #pragma surface surf Lambert alpha
15.  
16.                  struct Input {
17.                     float2 uv_MainTex;
18.                 };
19.  
20.                 sampler2D _MainTex;
21.                 float4 _MaskCol;
22.                 float _Sensitivity;
23.                  float _Smooth;
24.  
25.                 void surf (Input IN, inout SurfaceOutput o) {
26.                         half4 c = tex2D (_MainTex, IN.uv_MainTex);
27.  
28.                         float maskY = 0.2989 * _MaskCol.r + 0.5866 * _MaskCol.g + 0.1145 * _MaskCol.b;
29.                         float maskCr = 0.7132 * (_MaskCol.r - maskY);
30.                          float maskCb = 0.5647 * (_MaskCol.b - maskY);
31.  
32.                         float Y = 0.2989 * c.r + 0.5866 * c.g + 0.1145 * c.b;
33.                          float Cr = 0.7132 * (c.r - Y);
34.                          float Cb = 0.5647 * (c.b - Y);
35.  
36.                          float blendValue = smoothstep(_Sensitivity, _Sensitivity + _Smooth, distance(float2(Cr, Cb), float2(maskCr, maskCb)));
37.                         o.Alpha = 1.0 * blendValue;
38.                         o.Emission = c.rgb * blendValue;              
39.                 }
40.                 ENDCG
41.         }
42.         FallBack "Diffuse"  
43. }

This is the script that put the material to the image.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5.  
6. public class streamCam : MonoBehaviour {
7.     public WebCamDevice[] devices;
8.     public int index;
9.     public RawImage rawImage;
10.     public Image image;
11.     public Rect rect;
12.     public Texture2D text2D;
13.     public Texture outText;
14.     public RenderTexture inText;
15.  
16.     // Use this for initialization
17.     void Start () {
18.         devices = WebCamTexture.devices;
19.         WebCamTexture webcamTexture = new WebCamTexture ();
20.         int i = 0;
21.         foreach(WebCamDevice cam in devices){
22.             print(cam.name+" "+i);
23.             i++;
24.         }
25.  
26.         Renderer renderer = GetComponent<Renderer>();
27.         webcamTexture.deviceName = devices[index].name;
28.  
29.         renderer.material.mainTexture = webcamTexture;
30.         rawImage.material = renderer.material;
31.         image.material = renderer.material;
32.         webcamTexture.Play();
33.         //renderer.material.SetColor("_MaskCol",new Color(0f,0.69f,.25f));
34.  
35.  
36.  
37.     }
38.    
39.     // Update is called once per frame
40.     void Update () {
41.         rect = new Rect (Vector2.zero,new Vector2(100f,100f));
42.         Renderer renderer = GetComponent<Renderer>();
43.         /*rawImage.material = renderer.material;
44.         rawImage.texture = renderer.material.mainTexture;*/
45.         image.material = renderer.material;
46.         text2D = renderer.material.mainTexture as Texture2D;
47.         image.sprite = Sprite.Create (text2D, rect, new Vector2(0f,0f));      
48.     }
49. }
50.