//Cg
//Cg profile arbvp1 arbfp1

// shader loosely based on pro-rsoft's from the panda3d forums
// shader assumes 6 texture stages:
// 0-2 textures
// 3-5 alpha maps
// vertex shader accepts unit 0 and 3 texture coords as input
// and outputs unit 0 scaled and unit 3 unchanged
// fragment shader uses unit 0 coordinates to access textures
// and unit 3 coordinates (un-scaled) to access alpha maps
// gsk, june-2008

void vshader( in float4 vtx_position : POSITION,
	      in float3 vtx_normal : NORMAL,
              in float2 vtx_texcoord0 : TEXCOORD0,
              in float2 vtx_texcoord3 : TEXCOORD3,
              in uniform float4x4 mat_modelproj,
	      in uniform float4x4 trans_model_to_world,
	      in uniform float3 k_lightvec,
	      in uniform float4 k_lightcolor,
	      in uniform float4 k_ambientlight,
	      in uniform float4 k_tscale,
	      in uniform float k_zscale,
	      out float4 l_brightness,
	      out float4 l_lightcolor,
	      out float4 l_mpos,
              out float2 l_texcoord0 : TEXCOORD0,
              out float2 l_texcoord3 : TEXCOORD3,
              out float4 l_position : POSITION)
{

  // worldspace position, for clipping in the fragment shader
  l_mpos = mul(trans_model_to_world, vtx_position);

  l_position=mul(mat_modelproj,vtx_position);
  l_texcoord0=vtx_texcoord0*k_tscale;
  l_texcoord3=vtx_texcoord3;
  vtx_normal.z /= k_zscale;

  // lighting
  float3 N = normalize( vtx_normal );
  float3 L = normalize( k_lightvec );
  l_brightness = (max( dot( -N, L ), 0.0f )*k_lightcolor)+k_ambientlight;


}

void fshader( in float4 l_position : POSITION,
              in float2 l_texcoord0 : TEXCOORD0,
              in float2 l_texcoord3 : TEXCOORD3,
	      in float4  l_brightness,
	      in float4 l_lightcolor,
	      in float4 l_mpos,
	      in uniform float4 k_waterlevel,
              in uniform sampler2D tex_0 : TEXUNIT0,
              in uniform sampler2D tex_1 : TEXUNIT1,
              in uniform sampler2D tex_2 : TEXUNIT2,
              in uniform sampler2D tex_3 : TEXUNIT3,
              in uniform sampler2D tex_4 : TEXUNIT4,
              in uniform sampler2D tex_5 : TEXUNIT5,
              out float4 o_color : COLOR )
{
  // clipping
  if ( l_mpos.z < k_waterlevel.z) discard;

  // alpha splatting and lighting
  float4 tex1=tex2D(tex_0,l_texcoord0);
  float4 tex2=tex2D(tex_1,l_texcoord0);
  float4 tex3=tex2D(tex_2,l_texcoord0);
  float alpha1=tex2D(tex_3,l_texcoord3).z;
  float alpha2=tex2D(tex_4,l_texcoord3).z;
  float alpha3=tex2D(tex_5,l_texcoord3).z;
  o_color =tex1*alpha1;
  o_color+=tex2*alpha2;
  o_color+=tex3*alpha3;
  //o_color *= 0.5;
  //o_color
  o_color=o_color*(l_brightness);
  //o_color=l_lightcolor;
  o_color.a=1.0;
}