if SERVER then return end

//This code can be improved a lot.
//Feel free to improve, use or modify in any way although credit would be appreciated.
//Global table
BSHADOWS = {}

//The original drawing layer
BSHADOWS.RenderTarget = GetRenderTarget("bshadows_original", ScrW(), ScrH())

//The shadow layer
BSHADOWS.RenderTarget2 = GetRenderTarget("bshadows_shadow", ScrW(), ScrH())

//The matarial to draw the render targets on
BSHADOWS.ShadowMaterial = CreateMaterial("bshadows", "UnlitGeneric", {
	[ "$translucent" ] = 1,
	[ "$vertexalpha" ] = 1,
	[ "alpha" ] = 1
})

//When we copy the rendertarget it retains color, using this allows up to force any drawing to be black
//Then we can blur it to create the shadow effect
BSHADOWS.ShadowMaterialGrayscale = CreateMaterial("bshadows_grayscale", "UnlitGeneric", {
	[ "$translucent" ] = 1,
	[ "$vertexalpha" ] = 1,
	[ "$alpha" ] = 1,
	[ "$color" ] = "0 0 0",
	[ "$color2" ] = "0 0 0"
})

//Call this to begin drawing a shadow
BSHADOWS.BeginShadow = function()
	//Set the render target so all draw calls draw onto the render target instead of the screen
	render.PushRenderTarget(BSHADOWS.RenderTarget)

	//Clear is so that theres no color or alpha
	render.OverrideAlphaWriteEnable(true, true)
	render.Clear(0, 0, 0, 0)
	render.OverrideAlphaWriteEnable(false, false)

	//Start Cam2D as where drawing on a flat surface
	cam.Start2D()
end

//Now leave the rest to the user to draw onto the surface
//This will draw the shadow, and mirror any other draw calls the happened during drawing the shadow
BSHADOWS.EndShadow = function(intensity, spread, blur, opacity, direction, distance, _shadowOnly)

	//Set default opcaity
	opacity = opacity or 255
	direction = direction or 0
	distance = distance or 0
	_shadowOnly = _shadowOnly or false

	//Copy this render target to the other
	render.CopyRenderTargetToTexture(BSHADOWS.RenderTarget2)

	//Blur the second render target
	if blur > 0 then
		render.OverrideAlphaWriteEnable(true, true)
		render.BlurRenderTarget(BSHADOWS.RenderTarget2, spread, spread, blur)
		render.OverrideAlphaWriteEnable(false, false)
	end

	//First remove the render target that the user drew
	render.PopRenderTarget()

	//Now update the material to what was drawn
	BSHADOWS.ShadowMaterial:SetTexture('$basetexture', BSHADOWS.RenderTarget)

	//Now update the material to the shadow render target
	BSHADOWS.ShadowMaterialGrayscale:SetTexture('$basetexture', BSHADOWS.RenderTarget2)

	//Work out shadow offsets
	local xOffset = math.sin(math.rad(direction)) * distance
	local yOffset = math.cos(math.rad(direction)) * distance

	//Now draw the shadow
	BSHADOWS.ShadowMaterialGrayscale:SetFloat("$alpha", opacity / 255) //set the alpha of the shadow
	render.SetMaterial(BSHADOWS.ShadowMaterialGrayscale)

	for i = 1, math.ceil(intensity) do
		render.DrawScreenQuadEx(xOffset, yOffset, ScrW(), ScrH())
	end

	if not _shadowOnly then

		//Now draw the original
		BSHADOWS.ShadowMaterial:SetTexture('$basetexture', BSHADOWS.RenderTarget)
		render.SetMaterial(BSHADOWS.ShadowMaterial)
		render.DrawScreenQuad()
	end

	cam.End2D()
end

//This will draw a shadow based on the texture you passed it.
BSHADOWS.DrawShadowTexture = function(texture, intensity, spread, blur, opacity, direction, distance, shadowOnly)
	//Set default opcaity
	opacity = opacity or 255
	direction = direction or 0
	distance = distance or 0
	shadowOnly = shadowOnly or false

	//Copy the texture we wish to create a shadow for to the shadow render target
	render.CopyTexture(texture, BSHADOWS.RenderTarget2)

	//Blur the second render target
	if blur > 0 then
		render.PushRenderTarget(BSHADOWS.RenderTarget2)
		render.OverrideAlphaWriteEnable(true, true)
		render.BlurRenderTarget(BSHADOWS.RenderTarget2, spread, spread, blur)
		render.OverrideAlphaWriteEnable(false, false)
		render.PopRenderTarget()
	end

	//Now update the material to the shadow render target
	BSHADOWS.ShadowMaterialGrayscale:SetTexture('$basetexture', BSHADOWS.RenderTarget2)

	//Work out shadow offsets
	local xOffset = math.sin(math.rad(direction)) * distance
	local yOffset = math.cos(math.rad(direction)) * distance

	//Now draw the shadow
	BSHADOWS.ShadowMaterialGrayscale:SetFloat("$alpha", opacity / 255) //Set the alpha
	render.SetMaterial(BSHADOWS.ShadowMaterialGrayscale)

	for i = 1, math.ceil(intensity) do
		render.DrawScreenQuadEx(xOffset, yOffset, ScrW(), ScrH())
	end

	if not shadowOnly then
		//Now draw the original
		BSHADOWS.ShadowMaterial:SetTexture('$basetexture', texture)
		render.SetMaterial(BSHADOWS.ShadowMaterial)
		render.DrawScreenQuad()
	end
end