title: 2D GLSL light radius/intensity
body: <p>I have a simple GLSL fragment shader that I'm using for 2D lights, is there any way to modify this to implement setting a light's radius and/or intensity? Currently the only modifications available are to the constant/linear/quadratic light attenuation.</p>
  
  <p>Here is the current shader code (not updated to modern OpenGL)</p>
  
  <pre><code>uniform vec2 lightpos;
  uniform vec4 lightColor;
  uniform float screenHeight;
  uniform vec3 lightAttenuation;
  uniform float radius; //Doesn't do anything
  uniform float intensity; //Doesn't do anything
  
  uniform sampler2D texture;
  
  void main()
  {       
      vec2 pixel=gl_FragCoord.xy;     
      pixel.y=screenHeight-pixel.y;   
      vec2 aux=lightpos-pixel;
      float distance=length(aux);
      float attenuation=1.0/(lightAttenuation.x+lightAttenuation.y*distance+lightAttenuation.z*distance*distance);
      vec4 color=vec4(attenuation,attenuation,attenuation,1.0)*lightColor;
      gl_FragColor = color;//*texture2D(texture,gl_TexCoord[0].st);
  }
  </code></pre>