acg_exp3/vshader71.glsl

#version 150

in  vec4 vPosition;
in  vec2 vTexCoord;

out vec4 color;
out vec2 texCoord;
out float fog_factor;

uniform int foggy;
uniform vec3 eye_pos;
uniform mat4 model_view;
uniform mat4 projection;

void main() {
  color       = vec4(1.0, 1.0, 1.0, 1.0);
  texCoord    = vTexCoord;
  gl_Position = projection * model_view *  vPosition / vPosition.w;

  // fog
  if (foggy > 0) {
    // distance
    float dis = (vPosition.x - eye_pos.x) * (vPosition.x - eye_pos.x)
              + (vPosition.y - eye_pos.y) * (vPosition.y - eye_pos.y)
              + (vPosition.z - eye_pos.z) * (vPosition.z - eye_pos.z);
    fog_factor = exp(-dis);
  } else { // not foggy
    fog_factor = 1.0;
  }
}