#include "ShaderConstantsGNM.h"

struct VS_Input {
	float3 position : POSITION;
	float4 color : COLOR;
	float2 uv0 : TEXCOORD_0;
	float2 uv1 : TEXCOORD_1;
};


struct PS_Input {
	float4 position : S_POSITION;

#ifndef BYPASS_PIXEL_SHADER
	float4 color : COLOR;
	float2 uv0 : TEXCOORD_0;
	float2 uv1 : TEXCOORD_1;
#endif

#ifdef FOG
	float4 fogColor : FOG_COLOR;
#endif
};


static const float rA = 1.0;
static const float rB = 1.0;
static const float3 UNIT_Y = float3(0, 1, 0);
static const float DIST_DESATURATION = 56.0 / 255.0; //WARNING this value is also hardcoded in the water color, don'tchange


PS_Input main(in VS_Input VSInput) 
{
	PS_Input PSInput = (PS_Input)0;

#ifndef BYPASS_PIXEL_SHADER
	PSInput.uv0 = VSInput.uv0;
	PSInput.uv1 = VSInput.uv1;
	PSInput.color = VSInput.color;
#endif

#ifdef AS_ENTITY_RENDERER
		PSInput.position = mul(WORLDVIEWPROJ, float4(VSInput.position, 1));
		float3 worldPos = PSInput.position.xyz;
#else
		float3 worldPos = (VSInput.position.xyz * CHUNK_ORIGIN_AND_SCALE.w) + CHUNK_ORIGIN_AND_SCALE.xyz;
		PSInput.position = mul(WORLDVIEW, float4( worldPos, 1 ));
		PSInput.position = mul(PROJ, PSInput.position);
#endif

///// find distance from the camera

#if defined(FOG) || defined(BLEND)
	#ifdef FANCY
		float3 relPos = -worldPos;
		float cameraDepth = length(relPos);
	#else
		float cameraDepth = PSInput.position.z;
	#endif
#endif

	///// apply fog

#ifdef FOG
	float len = cameraDepth / RENDER_DISTANCE;
#ifdef ALLOW_FADE
	len += CURRENT_COLOR.r;
#endif

	PSInput.fogColor.rgb = FOG_COLOR.rgb;
	PSInput.fogColor.a = clamp((len - FOG_CONTROL.x) / (FOG_CONTROL.y - FOG_CONTROL.x), 0.0, 1.0);

#endif

///// blended layer (mostly water) magic
#ifdef BLEND
	//Mega hack: only things that become opaque are allowed to have vertex-driven transparency in the Blended layer...
	//to fix this we'd need to find more space for a flag in the vertex format. color.a is the only unused part
	bool shouldBecomeOpaqueInTheDistance = VSInput.color.a < 0.95;
	if(shouldBecomeOpaqueInTheDistance) {
		#ifdef FANCY  /////enhance water
			float cameraDist = cameraDepth / FAR_CHUNKS_DISTANCE;
		#else
			float3 relPos = -worldPos.xyz;
			float camDist = length(relPos);
			float cameraDist = camDist / FAR_CHUNKS_DISTANCE;
		#endif //FANCY
		
		float alphaFadeOut = clamp(cameraDist, 0.0, 1.0);
		PSInput.color.a = lerp(VSInput.color.a, 1.0, alphaFadeOut);
	}
#endif
	
	return PSInput;
}
