source: data/branches/Shader_HS18/programs/Example/GLSLES/OffsetMappingVp.glsles @ 12091

#version 100

precision mediump int;
precision mediump float;

uniform vec4 lightPosition; // object space 
uniform vec3 eyePosition;   // object space 
uniform mat4 worldViewProj; // not actually used but here for compat with HLSL

varying vec3 oEyeDir;
varying vec3 oLightDir;
varying vec3 oHalfAngle;
varying vec4 oUv0;

attribute vec3 normal;
attribute vec3 tangent;
attribute vec4 uv0;
attribute vec4 position;

/* Vertex program that moves light and eye vectors into texture tangent space at vertex */ 

void main()
{
    // Calculate output position 
        gl_Position = worldViewProj * position;

    // Pass the main uvs straight through unchanged 
    oUv0 = uv0;

    vec3 lightDir = lightPosition.xyz - (position.xyz * lightPosition.w);

        vec3 eyeDir = eyePosition - position.xyz; 
    
        // Calculate the binormal (NB we assume both normal and tangent are
        // already normalised)
        // NB looks like nvidia cross params are BACKWARDS to what you'd expect
        // this equates to NxT, not TxN
        vec3 localbinormal = cross(tangent, normal);

        // Form a rotation matrix out of the vectors, column major for glsl es 
        mat3 TBN = mat3(vec3(tangent[0], localbinormal[0], normal[0]),
                                                vec3(tangent[1], localbinormal[1], normal[1]),
                                                vec3(tangent[2], localbinormal[2], normal[2]));
    
    // Transform the light vector according to this matrix 
        oLightDir = normalize(TBN * lightDir); 
        oEyeDir = normalize(TBN * eyeDir); 
    oHalfAngle = normalize(oEyeDir + oLightDir);
}