source: data/branches/Shader_HS18/programs/GLSL120/BumpMapping/Example_BumpMappingSpecularVp.glsl @ 12115

#version 120

// General functions
// parameters
uniform vec4 lightPosition; // object space
uniform vec3 eyePosition;   // object space
uniform mat4 worldViewProj;

attribute vec4 vertex;
attribute vec3 normal;
attribute vec3 tangent;
attribute vec4 uv0;

varying vec4 oUv0;
varying vec3 oTSLightDir;
varying vec3 oTSHalfAngle;

/* Vertex program which includes specular component */
void main()
{
        // calculate output position
        gl_Position = worldViewProj * vertex;

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

        // calculate tangent space light vector
        // Get object space light direction
        vec3 lightDir = normalize(lightPosition.xyz - (vertex * lightPosition.w).xyz);

        // Calculate the binormal (NB we assume both normal and tangent are
        // already normalised)
        vec3 binormal = cross(normal, tangent);
        
        // Form a rotation matrix out of the vectors
        mat3 rotation = mat3(vec3(tangent[0], binormal[0], normal[0]),
                                                vec3(tangent[1], binormal[1], normal[1]),
                                                vec3(tangent[2], binormal[2], normal[2]));
        
        // Transform the light vector according to this matrix
        oTSLightDir = rotation * lightDir;

        // Calculate half-angle in tangent space
        vec3 eyeDir = normalize(eyePosition - vertex.xyz);
        vec3 halfAngle = normalize(eyeDir + lightDir);
        oTSHalfAngle = rotation * halfAngle;
}