using UnityEngine;

namespace Scanner
{
	public class ScannerCameraEffect : MonoBehaviour
	{
		public Vector3 m_Origin;
		public Material m_Material;
		float m_ScanDistance;
		Camera m_Camera;

		public void SetScanDistance(float dist)
		{
			m_ScanDistance = dist;
		}
		public Material GetMaterial()
		{
			return m_Material;
		}
		void OnEnable()
		{
			m_Camera = GetComponent<Camera>();
			m_Camera.depthTextureMode = DepthTextureMode.Depth;
		}
		[ImageEffectOpaque]
		void OnRenderImage(RenderTexture src, RenderTexture dst)
		{
			m_Material.SetVector("_WorldSpaceScannerPos", m_Origin);
			m_Material.SetFloat("_ScanDistance", m_ScanDistance);
			RaycastCornerBlit(src, dst);
		}
		void RaycastCornerBlit(RenderTexture src, RenderTexture dst)
		{
			// calculate frustum corners
			float camFar = m_Camera.farClipPlane;
			float fovWHalf = m_Camera.fieldOfView * 0.5f;
			float camAspect = m_Camera.aspect;

			Vector3 toRight = m_Camera.transform.right * Mathf.Tan (fovWHalf * Mathf.Deg2Rad) * camAspect;
			Vector3 toTop = m_Camera.transform.up * Mathf.Tan (fovWHalf * Mathf.Deg2Rad);
			Vector3 topLeft = m_Camera.transform.forward - toRight + toTop;
			float camScale = topLeft.magnitude * camFar;

			topLeft.Normalize ();
			topLeft *= camScale;

			Vector3 topRight = m_Camera.transform.forward + toRight + toTop;
			topRight.Normalize ();
			topRight *= camScale;

			Vector3 bottomRight = m_Camera.transform.forward + toRight - toTop;
			bottomRight.Normalize ();
			bottomRight *= camScale;

			Vector3 bottomLeft = m_Camera.transform.forward - toRight - toTop;
			bottomLeft.Normalize ();
			bottomLeft *= camScale;

			// post process pass
			RenderTexture.active = dst;
			m_Material.SetTexture ("_MainTex", src);

			GL.PushMatrix ();
			GL.LoadOrtho ();

			m_Material.SetPass (0);

			GL.Begin (GL.QUADS);
			GL.MultiTexCoord2 (0, 0f, 0f);
			GL.MultiTexCoord (1, bottomLeft);
			GL.Vertex3 (0f, 0f, 0f);

			GL.MultiTexCoord2 (0, 1f, 0f);
			GL.MultiTexCoord (1, bottomRight);
			GL.Vertex3 (1f, 0f, 0f);

			GL.MultiTexCoord2 (0, 1f, 1f);
			GL.MultiTexCoord (1, topRight);
			GL.Vertex3 (1f, 1f, 0f);

			GL.MultiTexCoord2 (0, 0f, 1f);
			GL.MultiTexCoord (1, topLeft);
			GL.Vertex3 (0f, 1f, 0f);

			GL.End();
			GL.PopMatrix();
		}
	}
}