/*------------------.
| :: Description :: |
'-------------------/

	Compare (version 1.0)

	Author: CeeJay.dk
	License: MIT

	About:
	Compares the output of two effects against each other using difference blending.
	Place this effect between two other effects to see their differences.
	
	Usage:
	1. Enable Capture [Compare.fx]
	2. Enable effect A
	3. Enable Restore [Compare.fx]
	4. Enable effect B
	5. Enable Compare [Compare.fx]

	Ideas for future improvement:
	* Separator lines
	* More blend modes?
	* Moving separator
	* Mouse-set separator
	* Alpha comparison?

	History:
	(*) Feature (+) Improvement (x) Bugfix (-) Information (!) Compatibility
	
	Version 1.0 (Based on Splitscreen by CeeJay.dk)
	* Initial version for comparing two effects
	* Added difference blending with user scaling
	* Three-technique workflow: Capture -> Restore -> Compare
*/

/*------------------.
| :: UI Settings :: |
'------------------*/

#include "ReShadeUI.fxh"

uniform int ui_instructions 
<
	ui_category = "Instructions";
	ui_type = "radio";
	ui_label = " ";
	ui_text =
		"1. Enable 'Capture' technique first\n"
		"2. Enable Effect A\n"
		"3. Enable 'Restore' technique\n"
		"4. Enable Effect B\n"
		"5. Enable 'Compare' technique\n\n"
		"The Compare technique will show the differences between Effect A and Effect B using various visualization modes.";
>;

uniform int compare_mode 
<
	ui_type = "combo";
	ui_label = "Mode";
	ui_tooltip = "Choose a comparison mode";
	ui_spacing = 2;
	ui_items = 
	"Vertical 50/50 split\0"
	"Vertical 25/50/25 split\0"
	"Angled 50/50 split\0"
	"Angled 25/50/25 split\0"
	"Horizontal 50/50 split\0"
	"Horizontal 25/50/25 split\0"
	"Diagonal split\0"
	"Difference blend (absolute)\0"
	"Difference blend (signed)\0"
	;
> = 7;

uniform float difference_scale 
<
	ui_type = "slider";
	ui_label = "Difference Scale";
	ui_tooltip = "Multiplier for difference visibility";
	ui_min = 1.0;
	ui_max = 20.0;
	ui_step = 0.1;
> = 5.0;

/*---------------.
| :: Includes :: |
'---------------*/

#include "ReShade.fxh"

/*-------------------------.
| :: Texture and sampler:: |
'-------------------------*/

texture OriginalBuffer { Width = BUFFER_WIDTH; Height = BUFFER_HEIGHT; };
sampler OriginalSampler { Texture = OriginalBuffer; };

texture EffectABuffer { Width = BUFFER_WIDTH; Height = BUFFER_HEIGHT; };
sampler EffectASampler { Texture = EffectABuffer; };

/*-------------.
| :: Effect :: |
'-------------*/

// Capture: Store the original unprocessed buffer
float3 PS_Capture(float4 pos : SV_Position, float2 texcoord : TEXCOORD) : SV_Target
{
	return tex2D(ReShade::BackBuffer, texcoord).rgb;
}

// Restore: Display original image
float3 PS_Restore(float4 pos : SV_Position, float2 texcoord : TEXCOORD) : SV_Target
{
	return tex2D(OriginalSampler, texcoord).rgb;
}

// Compare: Compare the original and two effects
float3 PS_Compare(float4 pos : SV_Position, float2 texcoord : TEXCOORD) : SV_Target
{
	float3 original = tex2D(OriginalSampler, texcoord).rgb;  // Original unprocessed
	float3 effectA = tex2D(EffectASampler, texcoord).rgb;  // Effect A 
	float3 effectB = tex2D(ReShade::BackBuffer, texcoord).rgb;  // Effect B (current)
	float3 color;

	// -- Vertical 50/50 split --
	[branch] if (compare_mode == 0)
		color = (texcoord.x < 0.5) ? effectA : effectB;

	// -- Vertical 25/50/25 split: effectA | original | effectB --
	[branch] if (compare_mode == 1)
	{
		if (texcoord.x < 0.333)
			color = effectA;
		else if (texcoord.x < 0.666)
			color = original;
		else
			color = effectB;
	}

	// -- Angled 50/50 split --
	[branch] if (compare_mode == 2)
	{
		float dist = ((texcoord.x - 3.0/8.0) + (texcoord.y * 0.25));
		dist = saturate(dist - 0.25);
		color = dist ? effectB : effectA;
	}

	// -- Angled 25/50/25 split: effectA | original | effectB --
	[branch] if (compare_mode == 3)
	{
		float angle = texcoord.x + texcoord.y * 0.5;
		if (angle < 0.5)
			color = effectA;
		else if (angle < 1.0)
			color = original;
		else
			color = effectB;
	}

	// -- Horizontal 50/50 split --
	[branch] if (compare_mode == 4)
		color = (texcoord.y < 0.5) ? effectA : effectB;

	// -- Horizontal 25/50/25 split: effectA | original | effectB --
	[branch] if (compare_mode == 5)
	{
		if (texcoord.y < 0.333)
			color = effectA;
		else if (texcoord.y < 0.666)
			color = original;
		else
			color = effectB;
	}

	// -- Diagonal split --
	[branch] if (compare_mode == 6)
	{
		float dist = (texcoord.x + texcoord.y);
		color = (dist < 1.0) ? effectA : effectB;
	}

	// -- Difference blend (absolute) --
	[branch] if (compare_mode == 7)
	{
		float3 difference = abs(effectB - effectA);
		color = difference * difference_scale;
	}

	// -- Difference blend (signed) --
	[branch] if (compare_mode == 8)
	{
		float3 difference = effectB - effectA;
		color = (difference * difference_scale) + 0.5;
	}

	return color;
}

/*-----------------.
| :: Techniques :: |
'-----------------*/

technique Capture 
<
	ui_tooltip = "Step 1: Capture original image before any effects.";
>
{
	pass Capture_Original
	{
		VertexShader = PostProcessVS;
		PixelShader = PS_Capture;
		RenderTarget = OriginalBuffer;
	}
}

technique Restore 
<
	ui_tooltip = "Step 2: Capture Effect A and restore original image.";
>
{
	pass Capture_EffectA
	{
		VertexShader = PostProcessVS;
		PixelShader = PS_Capture;
		RenderTarget = EffectABuffer;
	}
	
	pass Restore
	{
		VertexShader = PostProcessVS;
		PixelShader = PS_Restore;
	}
}

technique Compare 
<
	ui_tooltip = "Step 3: Compare Effect A and Effect B with various visualization modes.";
>
{
	pass
	{
		VertexShader = PostProcessVS;
		PixelShader = PS_Compare;
	}
}