area.cs

//Author: Przemyslaw Zaworski, 07.12.2017
//Create custom render texture and assign material with area.shader
//Script calculates ratio between white shape and total UV area.
//It can be use for compute  surface area in real-time.
using UnityEngine;

public class area : MonoBehaviour 
{
	public ComputeShader compute_shader;
	public RenderTexture render_texture;
	public Material material;
	private GUIStyle gui_style = new GUIStyle();	
	[HideInInspector] public uint[] data;  
	protected ComputeBuffer compute_buffer;
	int handle_init;	
	int handle_main;
	float percent;
  
	void Start () 
	{       
		handle_init = compute_shader.FindKernel("CSInit");
		handle_main = compute_shader.FindKernel("CSMain");
		compute_buffer = new ComputeBuffer(1, sizeof(uint));
		data = new uint[1];
		compute_shader.SetTexture(handle_main, "image", render_texture);
		compute_shader.SetBuffer(handle_main, "compute_buffer", compute_buffer);
		compute_shader.SetBuffer(handle_init, "compute_buffer", compute_buffer);	  
	}
	
	void OnDestroy() 
	{
		if (null != compute_buffer) 
		{
			compute_buffer.Release();
			compute_buffer = null;
		}
	} 

	void Update()
	{
		compute_shader.Dispatch(handle_init, 64, 1, 1);
		compute_shader.Dispatch(handle_main, render_texture.width  / 8, render_texture.height  / 8, 1);       
		compute_buffer.GetData(data);
		uint result = data[0];
		percent = ((float)result/((float)render_texture.width*(float)render_texture.height))*100.0f;
		Graphics.Blit(material.mainTexture,render_texture,material);
	}
	
	void OnGUI()
	{
		gui_style.fontSize = 40;
		GUI.Label(new Rect(10, 10, 300, 20), "Percents "+percent.ToString(),gui_style);
	}
	
}