R"raw_string(
#version 120

attribute vec3 in_vertex;
attribute vec3 in_normal;

varying vec3 vertex;
varying vec3 normal;
varying vec3 lightDirection;

uniform mat4 model;
uniform vec3 lightPosition;

void main()
{
  // TODO: this becomes invalid when projection matrices are used
  vec3 p = (model*vec4(in_vertex, 1.0)).xyz;
  lightDirection = normalize(lightPosition - p);

  vertex = p.xyz;
  normal = normalize((model*vec4(in_normal.xyz, 0.0)).xyz);

  gl_Position = vec4(p, 1.0);
}
)raw_string"