float4x4 g_world_view;
float4x4 g_projection;
texture g_texture0;
float4 g_light_ambient;
float3 g_light_directional_direction;
float4 g_light_directional_diffuse;
float3 g_camera_lookat;

texture g_shadow_texture;
float4x4 g_viewtolight_projection;						

float g_shadowweight;

float g_shadowepsilon;

// ----------------------------------------------------------
sampler2D g_texsampler0 =
sampler_state
{
	Texture = <g_texture0>;
	MinFilter = Anisotropic;
	MagFilter = Anisotropic;
	MipFilter = Linear;
};

sampler2D g_shadow_sampler =
sampler_state
{
	Texture = <g_shadow_texture>;
	MinFilter = Point;
	MagFilter = Point;
	MipFilter = Point;
	AddressU = Clamp;
	AddressV = Clamp;
};

// ----------------------------------------------------------
struct VS_OUTPUT_TEX0
{
	float4 position: POSITION;
	float2 texcoord0: TEXCOORD0;
	float4 position_viewspace : TEXCOORD1;
	float3 normal: TEXCOORD2;
	float4 position_lightspace : TEXCOORD3;
};

// ----------------------------------------------------------

// ----------------------------------------------------------
// returns the factor that the diffuse light contributes with
// ----------------------------------------------------------
float DiffuseFactor(float3 a_normal, float3 a_lightdir)
{
	return max(0.0f, dot(a_normal, a_lightdir));
}

// ----------------------------------------------------------
// Vertex Shader: VertScene
// Desc: Process vertex for scene
// ----------------------------------------------------------
VS_OUTPUT_TEX0 VSTex0(float4 a_position: POSITION, float4 a_normal: NORMAL, float2 a_texcoord0: TEXCOORD0)
{
	VS_OUTPUT_TEX0 l_output;

	l_output.position_viewspace = mul(a_position, g_world_view);
	l_output.position = mul(l_output.position_viewspace, g_projection);
	l_output.normal = mul(a_normal, (float3x3)g_world_view);

	l_output.texcoord0 = a_texcoord0;

	l_output.position_lightspace = mul(l_output.position_viewspace, g_viewtolight_projection);

	return l_output;
}

// ----------------------------------------------------------
// Pixel Shader: PixScene
// Desc: Process pixel (do per-pixel lighting) for enabled scene
// ----------------------------------------------------------
float4 PSTex0(float2 a_texcoord0: TEXCOORD0, float4 a_position_viewspace : TEXCOORD1, float3 a_normal : TEXCOORD2, float4 a_position_lightspace : TEXCOORD3) : COLOR
{
	//transform from RT space to texture space.
	float2 l_shadowtexC = 0.5 * a_position_lightspace.xy / a_position_lightspace.w + float2(0.5, 0.5);
	l_shadowtexC.y = 1.0f - l_shadowtexC.y;

	float l_lightamount = 1.0f;

	// l_shadowtexC.x/y will have values between 0.0 and 1.0, if they are in the texturing area
	// - only then do we have to consider any kind of shadow
	if((!(l_shadowtexC.x < 0.0f || l_shadowtexC.x > 1.0f)) && (!(l_shadowtexC.y < 0.0f || l_shadowtexC.y > 1.0f)))
	{
		l_lightamount = (tex2D(g_shadow_sampler, l_shadowtexC) + g_shadowepsilon < a_position_lightspace.z / a_position_lightspace.w) ? 0.0f : 1.0f;

		if(l_lightamount < 1.0f)
			l_lightamount = g_shadowweight;
	}
	a_normal = normalize(a_normal);

	float4 l_diffuse = g_light_directional_diffuse * DiffuseFactor(a_normal, -g_light_directional_direction.xyz);

	// Light it
	float4 l_finalcolor = (tex2D(g_texsampler0, a_texcoord0) * (l_diffuse + g_light_ambient)) * l_lightamount;	// base color

	return l_finalcolor;
}

// ----------------------------------------------------------
// Technique: RenderScene
// Desc: Renders scene objects
// ----------------------------------------------------------
technique SimpleTexture
{
	pass p0
	{
		VertexShader = compile vs_2_0 VSTex0();
		PixelShader = compile ps_2_0 PSTex0();
	}
}