Sobel Shader as a Effect

[optimus007]

Is your feature request related to a problem?

Refereing to ths kalidoscope example i managed to get sobel added as a pass.
It works great but i have no blend options and cannot add it into the effect pass stack.

Describe the solution you'd like

Convert Sobel operator shader into an internal effect and maybe add controls to tweak the output (color , strength ,etc)

Additional context

three example https://threejs.org/examples/?q=sobel#webgl_postprocessing_sobel
three file https://github.com/mrdoob/three.js/blob/master/examples/jsm/shaders/SobelOperatorShader.js

Code I used to add Sobel Shader as a shader pass

	const shaderMaterial = new ShaderMaterial(SobelOperatorShader)
	const shaderPass = new ShaderPass(shaderMaterial, "tDiffuse")
	shaderMaterial.uniforms.resolution.value.x = window.innerWidth
	shaderMaterial.uniforms.resolution.value.y = window.innerHeight
	composer.addPass(shaderPass)

BTW Awesome work with the library !

[vanruesc]

Sorry for the late reply!

I'd like to add Sobel at some point, but I'm currently too busy with other issues.

[CodyJasonBennett]

Shared this in Discord for a question, but this is a straight ahead port -- https://codesandbox.io/s/sobel-effect-postprocessing-meyq7m. This doesn't look optimized at all though. I can try my hand at a pass specifically for postprocessing if there's a need.

[vanruesc]

Superceded by #583.