Activate the given pass for rendering.

Pass indices start from zero and go up to (but not including) passCount.

This is mostly used in direct drawing code using GL class. For example, Image Effects use materials for implementing screen post-processing. For each pass in the material they activate the pass and draw a fullscreen quad.

If SetPass returns false, you should not render anything.

Here is an example of a full image effect that inverts the colors. Add this script to the camera and see it in play mode.

	private var mat : Material;
	function Start () {
		mat = new Material (
			"Shader \"Hidden/Invert\" {" +
			"SubShader {" +
			"	Pass {" +
			"		ZTest Always Cull Off ZWrite Off" +
			"		SetTexture [_RenderTex] { combine one-texture }" +
			"	}" +
			"}" +
			"}"
		);
	}
	function OnRenderImage (source : RenderTexture, dest : RenderTexture) {
		RenderTexture.active = dest;
		source.SetGlobalShaderProperty ("_RenderTex");
		GL.PushMatrix ();
		GL.LoadOrtho ();
		// activate the first pass (in this case we know it is the only pass)
		mat.SetPass (0);
		// draw a quad
		GL.Begin (GL.QUADS);
		GL.TexCoord2 (0, 0); GL.Vertex3 (0, 0, 0.1);
		GL.TexCoord2 (1, 0); GL.Vertex3 (1, 0, 0.1);
		GL.TexCoord2 (1, 1); GL.Vertex3 (1, 1, 0.1);
		GL.TexCoord2 (0, 1); GL.Vertex3 (0, 1, 0.1);
		GL.End ();
		GL.PopMatrix ();
	}

See Also: passCount property, GL class, ShaderLab documentation.