#version 450 core
uniform vec3 lightPos;
uniform vec4 lumRad;
uniform sampler2D screenTexture;
in vec2 vTexPos;
out vec4 fColor;
float rad = lumRad.a;
void main() {
  vec3 distVec = texture(screenTexture, vTexPos).xyz - lightPos;
  float dist = dot(distVec, distVec);
  if (dist > rad) {
    discard;
  }
  float x = 1 - dist / rad;
  vec3 c = (x * x * x) * lumRad.rgb;
  fColor = vec4(c, 0);
}