//========== Copyright (c) Valve Corporation, All rights reserved. ==========//

// DYNAMIC: "D_NUM_BLUR_SAMPLES" "0..14"

#ifdef HDRTYPE
 #undef HDRTYPE
#endif
#define HDRTYPE HDR_TYPE_NONE

// Includes =======================================================================================
#include "common_ps_fxc.h"

// Texture Samplers ===============================================================================
sampler g_tTexSampler : register( s0 );

// Shaders Constants and Globals ==================================================================
float g_flMaxMotionBlur : register( c0 );
float4 g_vConst5 : register( c1 );
#define g_vGlobalBlurVector        g_vConst5.xy
#define g_flFallingMotionIntensity g_vConst5.z
#define g_flRollBlurIntensity      g_vConst5.w

float4 g_vViewport : register( c2 );

// Interpolated values ============================================================================
struct PS_INPUT
{
	float2 vUv0 : TEXCOORD0;
};

// Main ===========================================================================================
float4 main( PS_INPUT i ) : COLOR
{
	// Calculate blur vector
	float2 vFallingMotionBlurVector = ( ( i.vUv0.xy * 2.0f ) - 1.0f );
	float2 vRollBlurVector = cross( float3( vFallingMotionBlurVector.xy, 0.0f ), float3( 0.0f, 0.0f, 1.0f ) ).xy;
	float2 vGlobalBlurVector = g_vGlobalBlurVector;
	vGlobalBlurVector.y = -vGlobalBlurVector.y;
	//vGlobalBlurVector.xy = float2( 1.0f, 0.0f ); // For debugging

	float flFallingMotionBlurIntensity = -abs( g_flFallingMotionIntensity ); // Keep samples on screen by keeping vector pointing in
	//flFallingMotionBlurIntensity = step( 10, abs(g_flFallingMotionIntensity) ); // For finding the sweet spot in debug mode
	vFallingMotionBlurVector.xy *= dot( vFallingMotionBlurVector.xy, vFallingMotionBlurVector.xy ); // Dampen the effect in the middle of the screen
	vFallingMotionBlurVector.xy *= flFallingMotionBlurIntensity;

	float flRollBlurIntensity = g_flRollBlurIntensity;
	vRollBlurVector.xy *= flRollBlurIntensity;

	float2 vFinalBlurVector = vGlobalBlurVector.xy + vFallingMotionBlurVector.xy + vRollBlurVector.xy;
	#if defined( _X360 ) // Disable falling blur on the 360 for perf
		vFinalBlurVector.xy = vGlobalBlurVector.xy + vRollBlurVector.xy;
	#endif

	// Clamp blur vector to max length
	if ( length( vFinalBlurVector.xy ) > g_flMaxMotionBlur )
	{
		vFinalBlurVector.xy = normalize( vFinalBlurVector.xy ) * g_flMaxMotionBlur;
	}

	// Clamp fetches to viewport
	float2 vBlurVectorClamped = i.vUv0.xy + vFinalBlurVector.xy;
	vBlurVectorClamped.xy = clamp( vBlurVectorClamped.xy, g_vViewport.xy, g_vViewport.wz ) - i.vUv0.xy;

	// Set number of samples
	int nNumSamples = D_NUM_BLUR_SAMPLES + 1; // Make sure we always fetch 1 texel!

	// Step size
	float2 vUvOffset = { 0.0f, 0.0f };
	#if ( D_NUM_BLUR_SAMPLES > 0 )
		vUvOffset.xy = vBlurVectorClamped.xy / ( nNumSamples - 1 );
	#endif

	float4 cColor = { 0.0f, 0.0f, 0.0f, 0.0f };
	#if defined( _X360 )
		[unroll]
	#endif
	for ( int x = 0; x <= D_NUM_BLUR_SAMPLES; x++ )
	{
		// Calculate uv
		float2 vUvTmp = i.vUv0.xy + ( vUvOffset.xy * x );

		// Sample pixel
		//cColor += kernel[x] * tex2D( g_tTexSampler, vUvTmp ); // Use kernal from above
		cColor += ( 1.0f / nNumSamples ) * tex2D( g_tTexSampler, vUvTmp.xy ); // Evenly weight all samples
	}

	return float4( cColor.rgb, 1.0f );
}