#include "atmosphere.cg"
#include "lighting.cg"
#include "shadowmapping.cg"

// mod function shamelessly copied from GPU Gems.  Original author Li-Yi Wei
float2 mod(const float2 a, const float2 b)

{

  // emulate integer mod operations in a float-only environment

  return floor(frac(a/b) * b);

}

// Vertex to pixel shader structure
struct v2p
{
  float4 Position       : TEXCOORD4; //POSITION;
  float3 normal         : TEXCOORD5;
  float3 RayleighColor	: TEXCOORD2;
  float3 MieColor       : TEXCOORD3;
  float3 tc0            : TEXCOORD0;
  float3 Direction      : TEXCOORD1;
  float  extinction     : TEXCOORD6;
  //float2 vpos           : VPOS;
};

void main(

  // In
  in v2p IN,

  // Out
  out float4 outColor   : COLOR0,
#ifdef CSM_MRT
  out float4 outShadow  : COLOR1,
#endif

  // Constants
  uniform sampler2D baseMap : TEXUNIT0,
  uniform sampler2D indexMap : TEXUNIT1,
  uniform float3    lightDirection,
  uniform float3    lightColor,
  uniform float3    lightAmbient,
  uniform float3    eyePosW,
  uniform float     atmosRayleigh,
  uniform float     atmosMie,
  uniform float3    Ke,
  uniform float3    Ka,
  uniform float3    Kd,
  uniform float3    Ks,
  uniform float     shininess,
#ifdef CSM
	uniform sampler2D    shadowArray  : TEXUNIT7,
  uniform float4x4     smTexMatArray[SM_MAX_SPLITS],
  uniform float smSplits,
#endif
  uniform float     sunny,
  uniform float     exposure,
  uniform float		scale
)
{
  float3 skyColor;

#ifdef CSM
  float shadow;
  // Output shadowing and normals
  shadow=GetShadowFactor(IN.Position, IN.normal,shadowArray, smTexMatArray, smSplits, lightDirection)*sunny;
  //outShadow.rgb = IN.normal;
#else
  const float shadow=sunny;
#endif

  // Get sky gradient color
  skyColor.rgb=GetSkyColor(lightDirection,IN.Direction,IN.RayleighColor,IN.MieColor,atmosRayleigh,atmosMie,lightColor,lightAmbient);

  // Get base texture color
  // this is where the modifications go.  Making this the wang tiling version of standard.
  float2 mappingScale1 = float2(1.0f,1.0f)/scale;
  float2 mappingScale2 = float2((128.0f),(128.0f));
  float2 mappingAddress = IN.tc0 * mappingScale1; // In.tc0, IN.Position.xz
  float4 whichTile = tex2D(indexMap, float2(0.5f,0.5f)/mappingScale2 + floor(mappingAddress)/mappingScale2);

  //float4 whichTile = tex2D(indexMap,mappingAddress);
  // truncate values to make sure edges are crisp
  whichTile = floor(whichTile*3.0f + 0.25f)/4.0f;
  // number of input tiles (should be 4?)
  float2 tileScale = float2(4,4);
  // get correct mipmapping? Don't know if this code works in Racer.
  float2 tileScaledTex = mappingAddress * 0.25f;
  float4 baseCol=tex2D(baseMap,whichTile.wy + frac(mappingAddress)*float2(0.25,0.25), ddx(tileScaledTex),ddy(tileScaledTex));
  // debug tinting of each tile to make it more obvious what's going on
  // baseCol = whichTile.wyzz*0.5 + 0.5*baseCol;

  // Lighting
  float3 ambient,diffuse,specular;
  LightingSun(Ke,Ka,Kd,Ks,shininess,lightDirection,lightColor,lightAmbient,IN.Position.xyz,IN.normal,eyePosW,
    ambient,diffuse,specular);

  // Store shadowed color in COLOR0, lit color additions (spec+diff) in COLOR1
  float3 sdColor=baseCol*diffuse+specular;
  float3 ambientColor=baseCol*(ambient+Ke);

  // HDR toning of sky (for LDR shaders)
  //skyColor.rgb=1.0-exp(-exposure*skyColor.rgb);

#ifdef CSM_MRT
  // Mix sky with texture color based on atmospheric influence
  outColor.rgb=lerp(skyColor,ambientColor,IN.extinction);
  //outShadow.rgb=lerp(skyColor*(IN.extinction),sdColor,IN.extinction);
  outShadow.rgb=sdColor*IN.extinction;
  outShadow.a=shadow;
//outColor.rgb=outShadow.a;
//outShadow.rgba=0;

  // Blending
  outColor.a=1; //baseCol.a;
  //outShadow.a=1; //baseCol.a;
#else
  // Mix sky with texture color based on atmospheric influence
  outColor.rgb=lerp(skyColor,ambientColor+sdColor*shadow,IN.extinction);
  // Blending
  outColor.a=baseCol.a;
#endif
}