Add code to make normal maps work. Joerg: don't worry about this change being done near a release, we have no track atm using this feature, so this code will remain sleeping until, probably, 0.8

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@10070 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/shaders/normalmap.vert

@@ -0,0 +1,24 @@
+// By http://content.gpwiki.org/index.php/OpenGL:Tutorials:GLSL_Bump_Mapping
+// Released under GNU FDL license, without invariant (so DFSG-compliant, see
+// http://wiki.debian.org/DFSGLicenses#Exception)
+
+varying vec4 passcolor; //The vertex color passed
+ varying vec3 LightDir; //The transformed light direction, to pass to the fragment shader
+ attribute vec3 tangent; //The inverse tangent to the geometry
+ attribute vec3 binormal; //The inverse binormal to the geometry
+ uniform vec3 lightdir; //The direction the light is shining
+ void main() 
+ {
+   //Put the color in a varying variable
+   passcolor = gl_Color;
+   //Put the vertex in the position passed
+   gl_Position = ftransform(); 
+   //Construct a 3x3 matrix from the geometry’s inverse tangent, binormal, and normal
+   mat3 rotmat = mat3(tangent,binormal,gl_Normal);
+   //Rotate the light into tangent space
+   LightDir = rotmat * normalize(lightdir);
+   //Normalize the light
+   normalize(LightDir); 
+   //Use the first set of texture coordinates in the fragment shader 
+   gl_TexCoord[0] = gl_MultiTexCoord0;
+ }