//**************************************************************************/
// Copyright 2014 Autodesk, Inc.
// All rights reserved.
// Use of this software is subject to the terms of the Autodesk license
// agreement provided at the time of installation or download, or which
// otherwise accompanies this software in either electronic or hard copy form.
//**************************************************************************/

#include "Common.ogsfh"

// Specify a default blur amount (number of samples in each direction, or the "radius" of the box
// filter) if none is specified.  Use to determine the number of samples per pixel, including the
// center sample.
// NOTE: This can have a maximum value of 12 to work within SM2.
#ifndef BLUR_AMOUNT
    #define BLUR_AMOUNT 10
#endif

// The source buffer and sampler.
uniform texture2D gSourceTex;
uniform sampler2D gSourceSamp = sampler_state
{
    texture = <gSourceTex>;
};

uniform vec4 gUVTransform : RelativeViewportDimensions;

GLSLShader PS_BlurHoriz
{
	void main()
	{
		vec2 direction = vec2(1.0f, 0.0f); // TODO

		int numSamples = BLUR_AMOUNT * 2 + 1;
		vec2 texelSize = 1.0 / gScreenSize;

		// Compute the per-sample offset, based on the texel size and blur direction.  Then compute the
		// location of the starting sample, using the number of taps.
		vec2 offset = direction * texelSize;
		vec2 UV = VSUV * gUVTransform.zw + gUVTransform.xy - offset * (numSamples - 1) * 0.5f;
		
		// Sum each of the samples (box filter).
		vec4 sum = vec4(0, 0, 0, 0);
		for (int i = 0; i < numSamples; i++)
		{
			// Add the value from the source texture.
			sum += texture2D(gSourceSamp, clamp(UV, 0.0f, 1.0f));
			
			// Increment the texture coordinates by the offset.
			UV += offset;
		}
		
		// Return the average color and alpha.
		colorOut = sum / numSamples;
	}
}

GLSLShader PS_BlurVert
{
	void main()
	{
		vec2 direction = vec2(0.0f, 1.0f);

		int numSamples = BLUR_AMOUNT * 2 + 1;
		vec2 texelSize = 1.0 / gScreenSize;

		// Compute the per-sample offset, based on the texel size and blur direction.  Then compute the
		// location of the starting sample, using the number of taps.
		vec2 offset = direction * texelSize;
		vec2 UV = VSUV * gUVTransform.zw + gUVTransform.xy - offset * (numSamples - 1) * 0.5f;
		
		// Sum each of the samples (box filter).
		vec4 sum = vec4(0, 0, 0, 0);
		for (int i = 0; i < numSamples; i++)
		{
			// Add the value from the source texture.
			sum += texture2D(gSourceSamp, clamp(UV, 0.0f, 1.0f));
			
			// Increment the texture coordinates by the offset.
			UV += offset;
		}
		
		// Return the average color and alpha.
		colorOut = sum / numSamples;
	}
}

// Horizontal blur technique.
technique BlurHoriz
{
    pass p0
    {
        VertexShader (in VS_INPUT_ScreenQuad, out VS_TO_PS_ScreenQuad) = VS_ScreenQuad;
        PixelShader (in VS_TO_PS_ScreenQuad, out pixelOut) = PS_BlurHoriz;
    }
}

// Vertical blur technique.
technique BlurVert
{
    pass p0
    {
        VertexShader (in VS_INPUT_ScreenQuad, out VS_TO_PS_ScreenQuad) = VS_ScreenQuad;
        PixelShader (in VS_TO_PS_ScreenQuad, out pixelOut) = PS_BlurVert;
    }
}