// shader_skydome.fx v2
// Author: Ren712/AngerMAN

float4x4 gWorldViewProjection : WORLDVIEWPROJECTION;
float pi = 3.141592653589793;

texture gTEX;
float3 gObjScale=(1,1,1);
float3 gTexScale=(1,1,1);
float gColorAdd=0;
float gColorPow=1;
float gAlpha=1;
bool makeAngular=false;
//---------------------------------------------------------------------
//-- Sampler for the main texture (needed for pixel shaders)
//---------------------------------------------------------------------


sampler texMap = sampler_state
{
	Texture = (gTEX);
    MinFilter = Linear;
    MagFilter = Linear;
    MipFilter = None;
    AddressU = Wrap;
    AddressV = Wrap;
};


//---------------------------------------------------------------------
//-- Structure of data sent to the vertex shader
//--------------------------------------------------------------------- 
 
 struct VSInput
{
    float4 Position : POSITION; 
    float3 TexCoord : TEXCOORD0;
};

//---------------------------------------------------------------------
//-- Structure of data sent to the pixel shader ( from the vertex shader )
//---------------------------------------------------------------------

struct PSInput
{
    float4 Position : POSITION; 
	float3 TexCoord : TEXCOORD0;	
};

	
//-----------------------------------------------------------------------------
//-- VertexShader
//-----------------------------------------------------------------------------
PSInput VertexShaderSB(VSInput VS)
{
    PSInput PS = (PSInput)0;
	VS.Position.xy*=gObjScale.xy;
	VS.Position.z*=gObjScale.z;
    PS.Position = mul(VS.Position, gWorldViewProjection);
	PS.TexCoord=VS.TexCoord.xyz;
    return PS;
}

// original code from
// https://github.com/notlion/streetview-stereographic/blob/master/index.html
// translated to hlsl and reconfigured by me.

float2 angularTEX(float2 texCoords)
{
   float2 rads=float2(pi*2.0,-pi*0.5);
   texCoords.xy=2*(texCoords.xy-0.5);
   // Project to Sphere
   float x2y2 =(texCoords.x * texCoords.x + texCoords.y * texCoords.y);
   float3 sphere_pnt = float3(texCoords.x,texCoords.y, x2y2- 1.0 ) / (x2y2+ 1.0 );
   // Convert to Spherical Coordinates
   float r = length(sphere_pnt);
   float lon =atan2(sphere_pnt.x, sphere_pnt.y); 
   float lat = acos(sphere_pnt.z/ r);
   return float2(lon, lat)/ rads;
}

//-----------------------------------------------------------------------------
//-- PixelShader
//-----------------------------------------------------------------------------

float4 PixelShaderSB(PSInput PS) : COLOR0
{	
	float3 TexCoord = PS.TexCoord.xyz;
	if (makeAngular==true) {TexCoord.xy=angularTEX(TexCoord.xy);}
	float4 Tex = tex2D(texMap, TexCoord*gTexScale);
    return float4(pow(Tex.rgb+gColorAdd,gColorPow),Tex.a*gAlpha);
}


////////////////////////////////////////////////////////////
//////////////////////////////// TECHNIQUES ////////////////
////////////////////////////////////////////////////////////
technique skybox_alt
{	
	pass P0
    {
		AlphaRef = 1;
		AlphaBlendEnable = TRUE;
		VertexShader = compile vs_2_0 VertexShaderSB();
        PixelShader = compile ps_2_0 PixelShaderSB();
    }
	
}