ppsspp/assets/shaders/bloom.fsh

// Simple Bloom shader; created to use in PPSSPP.
// Without excessive samples and complex nested loops
// (to make it compatible with low-end GPUs and to ensure ps_2_0 compatibility).

#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif

uniform sampler2D sampler0;
varying vec2 v_texcoord0;	

float amount = 0.75; // suitable range = 0.00 - 1.00
float power = 0.5; // suitable range = 0.0 - 1.0

void main()
{
  vec3 color = texture2D(sampler0, v_texcoord0.xy).xyz;
  vec4 sum = vec4(0);
  vec3 bloom;
  
  for(int i= -2 ;i < 2; i++)
  {
    sum += texture2D(sampler0, v_texcoord0 + vec2(-1, i)*0.004) * amount;
    sum += texture2D(sampler0, v_texcoord0 + vec2(0, i)*0.004) * amount;
    sum += texture2D(sampler0, v_texcoord0 + vec2(1, i)*0.004) * amount;
  }
      
  if (color.r < 0.3)
  {
    bloom = sum.xyz*sum.xyz*0.012 + color;
  }
  else
  {
    if (color.r < 0.5)
      {
         bloom = sum.xyz*sum.xyz*0.009 + color;
      }
    else
      {
        bloom = sum.xyz*sum.xyz*0.0075 + color;
      }
  }
  
  bloom = mix(color, bloom, power);
  gl_FragColor.rgb = bloom;
  gl_FragColor.a = 1.0;
}