source: data/data_extern/programs/GLSL120/Example_FresnelVp.glsl

#version 120

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

uniform mat4 worldViewProjMatrix;
uniform vec3 eyePosition; // object space
uniform float timeVal;
uniform float scale;  // the amount to scale the noise texture by
uniform float scroll; // the amount by which to scroll the noise
uniform float noise;  // the noise perturb as a factor of the time

varying vec3 noiseCoord;
varying vec4 projectionCoord;
varying vec3 eyeDir;
varying vec3 oNormal;

// Vertex program for fresnel reflections / refractions
void main()
{
        gl_Position = worldViewProjMatrix * position;
        // Projective texture coordinates, adjust for mapping
        mat4 scalemat = mat4(0.5, 0.0, 0.0, 0.0, 
                         0.0, -0.5, 0.0, 0.0,
                         0.0, 0.0, 0.5, 0.0,
                         0.5, 0.5, 0.5, 1.0);
        projectionCoord = scalemat * gl_Position;

        // Noise map coords
        noiseCoord.xy = (uv0.xy + (timeVal * scroll)) * scale;
        noiseCoord.z = noise * timeVal;

        eyeDir = normalize(position.xyz - eyePosition); 
        oNormal = normal.rgb;
}