Irrlicht Engine

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 // "sio2" wrote the original code for this cool shader, but the App Project would have been great to have! 
 
 // Note: I only posted this because someone out there like me might benefit from it..
 // For me it shed some light on my problem..
 // I still don't understand why I sometimes get error messages, but it renders..
 
 // Just replace the HLSL code with this..
 // I changed a few things..
 
 bool parallaxMapping; 
 // Ensure samplers read from correct registers
 sampler2D  decalMap    : register(s0); // Seen these before..
 sampler2D  normalMap   : register(s1); // O.K!
 sampler2D  heightMap   : register(s2); // Mmmm..
 sampler2D  glossMap    : register(s3); // Aha!
 
 float4x4   mWorldViewProj;     // World * View * Projection transformation
 float4x4   mInvWorld;          // Inverted world matrix
 float4x4   mWorldView;         // Transposed world matrix
 float3     mEyePos;            // Eye position
 float3     mLightPos;          // Light position
 float4     mLightAmbient;      // Light ambient colour
 float4     mLightDiffuse;      // Light diffuse colour
 
 // irr::video::S3DVertexTangents
 struct VS_IN 
  {float3 Pos      : POSITION;
   float3 Normal   : NORMAL;
   float4 Color    : COLOR0;
   float2 Tex0     : TEXCOORD0;
   float3 Tangent  : TEXCOORD1; // This gives us our Tangents & Binormals..
   float3 Binormal : TEXCOORD2; // Do not use - binormal calculated in shader  (Mmmm..)
                                // The Appcode "SHOULD HAVE" done this!
 
   // float3 Tangent  : TANGENT; // THIS IS WHAT IT WAS (which Im not sure about, but could be old imlementation)
   // float3 Binormal : BINORMAL; // Do not use - binormal calculated in shader (Mmmm..)
   // Uncomment the above two (and comment the others) to see that "TANGENT" and "BINORMAL" 
   // Channel Semantics don't give joy.
  };
 
 // Output from from Vetex Shader and input to Pixel Shader
 struct VS_OUT 
  {float4 Pos            : POSITION;
   float2 TexCoord       : TEXCOORD0;
   float3 lightVec       : TEXCOORD1; // Dont serve as Tangent anymore.. O.K.
   float3 halfVec        : TEXCOORD2;
   float3 eyeVec         : TEXCOORD3;
   float3 PassedValue    : TEXCOORD4; // NEW.. I wanted to see things in the render..
   
  };
  
 // -------------------------------------------------------
 // Vertex shader's main entry point.
 
 // Bump mapping with parallax offset.
 // -------------------------------------------------------
 VS_OUT vertexMain(VS_IN In)
  {VS_OUT Out = (VS_OUT)0;
   // output vertex position
   Out.Pos = mul(float4(In.Pos,1), mWorldViewProj);
   float3 n = normalize(mul((float3x3)mInvWorld, In.Normal));
   float3 t = normalize(mul((float3x3)mInvWorld, In.Tangent));
   float3 b = normalize(mul((float3x3)mInvWorld, In.Binormal)); // Again, Apcode MUST do this..
   //float3 b = cross(n, t);  // This gives an apparent desired visual effect, but believe me, don't do it..
                              // Feel free to debate this.. (I really tried but no joy, and after seeing
                              // Nvidia FX Composer examples also steer clear of this, I'm convinced)
                              // Things may have changed since, so...
 
   // output texture coordinates for decal and normal maps
   Out.TexCoord = In.Tex0;
   // transform light and half angle vectors by tangent basis
   // mLightPos = mEyePos; // WE "CANNOT" ASSIGN INPUT VARIABLES FED FROM APPCODE ??..
   float3 LocalLightPos = mLightPos;
   //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
 
   // Why does this cause the error messages????
   // LocalLightPos = mEyePos;  // The inherent problem with this becomes apparent when you uncomment this..
                                // For some reason I cannot fathom it also causes error messages but renders.
   
   float3 TempVal;
   TempVal.x = mEyePos.x;
   TempVal.y = mEyePos.y;
   TempVal.z = mEyePos.z;
   float3 SecLightPos = LocalLightPos;
   
   // Uncomment this to see in the console window why I say what I say..
   // SecLightPos.x = TempVal.x; // Neither one of these are FED, so what is the problem?
   // SecLightPos.y = TempVal.y; // ALSO CAUSES ERRORS! (*&^#^$)
   // SecLightPos.z = TempVal.z; // ..
   
   //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
   
   
   // float3 Silencer = mLightPos;
 
   float3 v;
    v.x = dot (float3 (SecLightPos), t);
    v.y = dot (float3 (SecLightPos), b);
    v.z = dot (float3 (SecLightPos), n);
 
 
   // v.x = dot (float3 (mEyePos), t);  // ALSO CAUSES ERRORS! (D3D HLSL is like drinking bitter medicine)
   // v.y = dot (float3 (mEyePos), b);  // Simply wanted to temporarily assign Eye pos to light pos..
   // v.z = dot (float3 (mEyePos), n);
   
   
   Out.lightVec = normalize (v);
   // float3 halfVector = normalize(mLightPos - Out.Pos); // Order looks right..
   // float3 halfVector = normalize(Out.Pos - mLightPos); // Order looks right..
 
   // float3 halfVector = normalize(SecLightPos - Out.Pos);
   
    float3 halfVector = normalize(mEyePos - Out.Pos);
    
    
   halfVector = normalize(halfVector + mEyePos);
   v.x = dot (halfVector, t);
   v.y = dot (halfVector, b);
   v.z = dot (halfVector, n);
   Out.halfVec = normalize (v);
   float3 eyeVec = float3 (mul((float3x3)mWorldView, In.Pos));
   v.x = dot(eyeVec, t);
   v.y = dot(eyeVec, b);
   v.z = dot(eyeVec, n);
   Out.eyeVec = normalize(v);
   
   // Out.PassedValue   = In.Tangent;  // xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
   
   // Uncomment different ones..
   // Out.PassedValue   = t;   
   // Out.PassedValue   = b; // This gives no joy if you didn't try cross with normal
   // which isn't a good idea anyway..
    
   Out.PassedValue = n;  // Gives Vertex Normal..
   
   
   return Out;
  }
 
 
// -------------------------------------------------------
// Fragment shader's main entry point.
// Bump mapping with parallax offset.  I take inspiration
// from nVidia's bump mapping demo for this program.
// -------------------------------------------------------
 
 float4 pixelMain (VS_OUT In) : COLOR
  {float2 texCoords;
   if (parallaxMapping)
    {// use parallax mapping
     float height = tex2D(heightMap, In.TexCoord.xy).x;
     height = height * 0.04 - 0.02;
     float3 eye = normalize(In.eyeVec);
     texCoords = In.TexCoord.xy + (eye.xy * height);
    }
   else 
    {// standard bump mapping
     texCoords = In.TexCoord.xy;
    }
   // fetch normal from normal map, expand to the [-1, 1] range, and normalize
   float3 MappedNormal = tex2D (normalMap, In.TexCoord.xy);
   // float3 normal = 2.0 * (tex2D (normalMap, In.TexCoord.xy).rbg - 0.5); // "rbg"??!
   float3 normal = (2.0 * MappedNormal) - 0.5;
   normal = normalize (normal);
   // compute diffuse lighting 
   float3 diffuse = max (dot (In.lightVec, normal), 0.0) * mLightDiffuse.rgb;
   float3 decalColor = tex2D(decalMap, texCoords).rgb;
   // compute specular lighting 
   float3 specularCoeff = tex2D (glossMap, texCoords).rgb;
   float specular = max (dot (In.halfVec, normal), 0.0);
   specular = pow (specular, 8.0);
   // output final color
   float3 finalDiffuse = diffuse * decalColor;
   float3 finalSpecular = specular * specularCoeff;
   
   float4 FinalOutput;
   
   FinalOutput = float4(finalDiffuse + finalSpecular, 1.0) + mLightAmbient;
   
   // Works, but the system screams error messages at you in the console..
   // FinalOutput.x = (In.PassedValue.x / 2.0) + 0.5; // Which depends on actions earlier....
   // FinalOutput.y = (In.PassedValue.y / 2.0) + 0.5; //   See lines 128 to 135..
   // FinalOutput.z = (In.PassedValue.z / 2.0) + 0.5;
   
 
   // FinalOutput.x = (normal.x / 2.0) + 0.5; // WORKS..
   // FinalOutput.y = (normal.y / 2.0) + 0.5;
   // FinalOutput.z = (normal.z / 2.0) + 0.5;
 
   // FinalOutput.x = normal.x;   // WORKS..
   // FinalOutput.y = normal.y;
   // FinalOutput.z = normal.z;
 
   
   // FinalOutput.x = MappedNormal.x;  // WORKS..
   // FinalOutput.y = MappedNormal.y;
   // FinalOutput.z = MappedNormal.z;
   
   FinalOutput.w = 1.0; // Just to be sure..
   
   
   // return float4(finalDiffuse+finalSpecular, 1.0) + mLightAmbient;
   return FinalOutput;
   
   // I am currently trying to call this from my appcode with my data...
}