local SobelMaterial = Material( "pp/sobel" )
SobelMaterial:SetMaterialTexture( "$fbtexture", render.GetScreenEffectTexture() );

// convars
local pp_sobel_threshold = CreateClientConVar( "pp_sobel_threshold", "0.11", false, false );
local pp_sobel = CreateClientConVar( "pp_sobel", "0", false, false );

/*------------------------------------
	DrawSobel()
------------------------------------*/
function DrawSobel( threshold )

	render.UpdateScreenEffectTexture();

	// update threshold value
	SobelMaterial:SetMaterialFloat( "$threshold", threshold );

	render.SetMaterial( SobelMaterial );
	render.DrawScreenQuad();
	
end


/*------------------------------------
	DrawInternal()
------------------------------------*/
local function DrawInternal()

	if ( !pp_sobel:GetBool() ) then return; end
	if ( !GAMEMODE:PostProcessPermitted( "sobel" ) ) then return; end

	DrawSobel( pp_sobel_threshold:GetFloat() );

end
hook.Add( "RenderScreenspaceEffects", "RenderSobel", DrawInternal );


/*------------------------------------
	BuildControlPanel()
------------------------------------*/
local function BuildControlPanel( panel )

	panel:AddControl( "Header", { Text = "#Sobel", Description = "" }  )
	panel:AddControl( "CheckBox", { Label = "#Enable", Command = "pp_sobel" }  )
	
	panel:AddControl( "Slider", {
		Label = "#Threshold",
		Command = "pp_sobel_threshold",
		Type = "Float",
		Min = "0",
		Max = "1"
	} );

end

/*------------------------------------
	AddPostProcessMenu()
------------------------------------*/
local function AddPostProcessMenu()

	spawnmenu.AddToolMenuOption( "PostProcessing", "PPShader", "Sobel", "#Sobel", "", "", BuildControlPanel, { SwitchConVar = "pp_sobel" } );

end
hook.Add( "PopulateToolMenu", "AddPostProcessMenu_Sobel", AddPostProcessMenu );