Reconstruct world position in screen-space from depth buffer

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2

Okay, managed to solve it. For posterity, here are the relevant parts of the shader:

vec3 computeWorldPosition(){
		// Convert screen coordinates to normalized device coordinates (NDC)
		
		float normalizedDepth = unpackRGBAToDepth(  texture2D( tDepth, vUv) ); 
		
		vec4 ndc = vec4(
			(vUv.x - 0.5) * 2.0,
			(vUv.y - 0.5) * 2.0,
			(normalizedDepth - 0.5) * 2.0,
			1.0);
		
		vec4 clip = uProjectionInverse * ndc;
		vec4 view = uMatrixWorld* (clip / clip.w);
		vec3 result = view.xyz;
		
		return result;
}

here are the relevant matrices:

uniforms.uProjectionInverse.value.copy(camera.projectionMatrixInverse);
uniforms.uViewInverse.value.copy(camera.matrixWorld);

Note that the “camera” here is the original camera used to render the scene over which the screen-space effect is being drawn and not the camera facing the quad of said effect.

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