removeShaderPass(shaderPass) {
        if(!this.gl) return;

        // remove from shaderPasses our array
        this.shaderPasses = this.shaderPasses.filter(element => element.uuid !== shaderPass.uuid);

        // remove from scene stacks
        this.scene.removeShaderPass(shaderPass);

        shaderPass = null;

        // clear the buffer to clean scene
        if(this.gl) this.clear();

        // we've removed an object, keep Curtains class in sync with our renderer
        this.onSceneChange();
    }
Removes a ShaderPass element (that has already been disposed) from the scene and the shaderPasses array

     params:
     @shaderPass (ShaderPass object): the shader pass to remove
*