/*
	=====================================================================
	Original Author  : vegeta1k95
	Link             : https://www.moddb.com/mods/stalker-anomaly/addons/heatvision-v02-extension-for-beefs-nvg-dx11engine-mod
	=====================================================================
*/

#ifdef USE_MSAA
	#ifndef SM_5
        Texture2DMS<float4,MSAA_SAMPLES> s_heat;
	#else
        Texture2DMS<float4> s_heat;
	#endif
#else
    Texture2D   s_heat;
#endif

#define FADE_DISTANCE_START 0.0     // 13.0
#define FADE_DISTANCE_END 100.0     // 20.0

#define COLOR_FAR_MIN float3 (0.0, 0.03, 0.07)  // 0.07
#define COLOR_FAR_MAX float3 (0.0, 0.03, 0.15)  // 0.15
    
    
#define COLOR_DBLUE  float3 (0.0, 0.10, 0.35)
#define COLOR_BLUE   float3 (0.0, 0.10, 0.5)
#define COLOR_LBLUE  float3 (0.0, 0.74, 1.0)
#define COLOR_GREEN  float3 (0.4, 1.0, 0.6)
#define COLOR_YELLOW float3 (1.0, 0.8, 0.0)
#define COLOR_RED    float3 (1.0, 0.2, 0.0)

#define COLOR_BLACK  float3 (0.0, 0.0, 0.0)
#define COLOR_WHITE  float3 (1.0, 1.0, 1.0)

#define color_background_min    COLOR_DBLUE
#define color_background_max    COLOR_BLUE

#define color_gradient_very_low color_background_max
#define color_gradient_low      COLOR_GREEN
#define color_gradient_warm     COLOR_YELLOW
#define color_gradient_hot      COLOR_RED
	
float3 normal_blur(float2 pos2d, int samples) 
{
    float3 accum = (0.0, 0.0, 0.0);

    for (int i = -samples; i < samples; i++) {        
        for (int j = -samples; j < samples; j++) {
    		accum += gbuf_unpack_normal(s_position.Load( int3( pos2d+float2(i,j), 0 ), 0).xy);
        }
	}
    
    accum /= (samples*samples*4);
    return accum;
}

float3 greyscale(float3 img)
{
    float Y = 0.6*img.x + 0.5*img.y + 0.55*img.z;
    return float3(Y, Y, Y); 
}

float3 infrared(gbuffer_data gbd, float2 HPos, float2 Tex0) 
{
	int BW = 1;
	
    float depth = gbd.P.z;
    float3 hotness = s_heat.Load(int3(Tex0 * screen_res.xy, 0 ), 0);
    float3 mixed;
    
    if (hotness.r > 0.0) 
    {
        int samples = lerp(15, 4, smoothstep(0.0, 60, depth));

        mixed = normal_blur(HPos, samples);
        mixed = normalize(mixed);
        float projection = dot(mixed, float3(0.0, 0.0, -1.0));
        
        if (projection <= 0.f) {
            mixed = color_background_max;
        } else {        
            mixed = lerp(color_gradient_very_low, color_gradient_hot, smoothstep(0, 1.0, projection));
        }

        mixed = lerp(color_background_max, mixed, hotness.r);
    } else if (hotness.g > 0.0) {
        float3 blur_2 = s_blur_2.Sample(smp_base, Tex0).rgb;
        float luminance = dot(blur_2, float3(0.299f, 0.587f, 0.114f));

        luminance *= hotness.g;

        if (luminance >= 0.4) {
            mixed = color_gradient_hot;
        } else if (luminance >= 0.3 && luminance < 0.4) {
            mixed = color_gradient_warm;
        } else if (luminance >= 0.1 && luminance < 0.3) {
            mixed = color_gradient_low;
        } else {
            float projection = dot(normalize(gbd.N), float3(0.0, 0.0, -1.0));       
            mixed = lerp(color_background_min, color_background_max, projection);
        }
    } else if (hotness.b > 0.0) {
        mixed = lerp(color_background_min, color_gradient_low, hotness.b);
    } else {
        float projection = dot(normalize(gbd.N), float3(0.0, 0.0, -1.0)); 

        if (depth <= 0) 
        {
            depth = FADE_DISTANCE_END;
        }

        if (depth < FADE_DISTANCE_START)
        {
            mixed = lerp(color_background_min, color_background_max, projection);
        }
        else
        {
            float arg = smoothstep(FADE_DISTANCE_START, FADE_DISTANCE_END, clamp(depth, FADE_DISTANCE_START, FADE_DISTANCE_END));
            float3 min_color = lerp(color_background_min, COLOR_FAR_MIN - float3(0.0, 0.0, 0.03), arg);
            float3 max_color = lerp(color_background_max, COLOR_FAR_MAX - float3(0.0, 0.0, 0.05), arg);
            mixed = lerp(min_color, max_color, projection);
        }
    }
    
    mixed = greyscale(mixed);

    return mixed;
}