Thank you abrodersen and sqrt for your replies.
@abrodersen:
Thanks for the info, will save me some headaches when (and if) I’ll have to work with non uniform scaling 
@sqrt:
I know there’s something wrong but I cannot tell you what… Maybe is the kind of perspective, maybe that texture fits better with a vertical plane. Or maybe my shaders are wrong ( this theory is far more reliable ).
btw here is my code:
vp:
varying vec3 LightDir;
varying vec3 EyeDir;
varying vec3 HalfVector;
varying float LightDistance;
varying vec2 TexCoords;
attribute vec3 Tangent;
//////////////////////////////////////////////////////////////////////////////
// Transforms a vector from eye space to tangent space
// Parameters:
// t -> Tangent to the vertex
// b -> Binormal to the vertex
// n -> Normal to the vertex
// vector -> Vector to transform (will be normalized)
// Output:
// Vector in tangent space
vec3 TransformToTangentSpace( in vec3 t , in vec3 b , in vec3 n , in vec3 vector )
{
vec3 v;
vec3 temp = normalize( vector );
v.x = dot ( vector , t);
v.y = dot ( vector , b);
v.z = dot ( vector , n);
return normalize(v);
}
void main()
{
vec3 lPos; // Light position ( eye space )
vec3 halfVec; // Light half vector
vec3 vertPos; // Vertex position ( eye space )
vec3 eyePosition = vec3( 0.0 , 0.0 , 0.0 );
vec3 eyeDirection = vec3( 0.0 , 0.0 , -1.0 );
//Put the vertex in the position passed
gl_Position = ftransform();
vec3 n = normalize ( gl_NormalMatrix * gl_Normal);
vec3 t = normalize ( gl_NormalMatrix * Tangent );
vec3 b = cross (n, t);
vertPos = vec3( gl_ModelViewMatrix * gl_Vertex );
lPos = gl_LightSource[0].position.xyz - vertPos;
LightDistance = length( lPos );
LightDir = TransformToTangentSpace( t , b, n , lPos );
halfVec = gl_LightSource[0].halfVector.xyz;
HalfVector = TransformToTangentSpace( t , b, n , halfVec );
EyeDir = TransformToTangentSpace( t , b, n , eyeDirection );
TexCoords = gl_MultiTexCoord1.xy;
}
fp:
uniform sampler2D Texture_Normal;
uniform sampler2D Texture_Color;
uniform sampler2D Texture_HeightMap;
varying vec3 HalfVector;
varying vec3 EyeDir;
varying vec3 LightDir;
varying vec2 TexCoords;
varying float LightDistance;
const float specularCoeff = 0.6;
//////////////////////////////////////////////////////////////////////////////
// Computes the diffuse coefficent for the current light
// Parameters:
// lightIdx -> Index of the light to use
// d -> Distance form the light from the point ( interpolated from vp )
// Output:
// the diffuse coefficent for the current light
vec4 ComputeLightDiffuse( in int lightIdx , in float d)
{
float attenuation = 1.0 / ( gl_LightSource[ lightIdx ].constantAttenuation +
gl_LightSource[ lightIdx ].linearAttenuation * d +
gl_LightSource[ lightIdx ].quadraticAttenuation * d * d );
vec4 diffuse = gl_LightSource[ lightIdx ].diffuse * attenuation;
return diffuse;
}
//////////////////////////////////////////////////////////////////////////////////////////////
// Expands a normal read from the bumpmap texture into a normalized vector
// Parameters:
// packedNormal -> Bump normal value read from the bumpmap texture
// Output:
// Normal unpacked
vec3 UnpackNormal( in vec4 packedNormal )
{
return ( vec3( packedNormal ) - 0.5) * 2.0;
}
void main()
{
vec3 lDir; // Normalized light direction in tangent space
vec3 eDir; // Normalized eye direction in tangent space
vec3 hVec; // Light half vector
vec2 uvCoord; // Texture coords
float height; // height offset for parallax mapping
vec3 bumpNorm; // normal to the pixel ( read from the normal map )
vec4 decalCol; // decal color ( read from color map )
vec4 diffuse; // Light diffuse coefficent
float nDotL; // Dot product between the light direction in tangent space and the pixel normal
float spec; // Specular factor
vec3 finalCol; // Final fragment color after the computations
lDir = normalize ( LightDir );
eDir = normalize ( EyeDir );
hVec = normalize ( HalfVector );
uvCoord = TexCoords;
// Parallax mapping...
height = texture2D (Texture_HeightMap, uvCoord ).r;
height = height * 0.04 - 0.02;
uvCoord = uvCoord + ( eDir.xy * height );
bumpNorm = UnpackNormal( texture2D( Texture_Normal, uvCoord ) );
decalCol = texture2D( Texture_Color, uvCoord );
// compute distance between the surface and the light position
diffuse = ComputeLightDiffuse( 0 , LightDistance );
//Find the dot product between the light direction and the normal
nDotL = max( dot( bumpNorm, lDir ), 0.0 );
// Specular factor
spec = max( dot( HalfVector , bumpNorm ), 0.0) ;
spec = pow( spec, 128.0 ) * specularCoeff;
finalCol = nDotL * decalCol.rgb;
finalCol = min( finalCol + spec , 1.0 );
gl_FragColor = vec4( finalCol , decalCol.a ) * diffuse;
}
if you want to try the .exe you can download the latest version from http://download.yousendit.com/A6D8DCFD26C2FF4F
Extract it in a folder and edit the config.cfg file so that the paths are correct.
You can find the shaders in the data\ folder.
Thank you
the problem as you might see from the image below is that I am able to light only the world ( the textured quad 
forget about the box in the middle ) that lies under the light source (the white dot) and only one corner of it (the lower left on the pic). I don’t really know what I’m doing wrong.
