
uniform sampler2D bgl_RenderedTexture;
uniform float bgl_RenderedTextureWidth;
uniform float bgl_RenderedTextureHeight;
uniform float sunX;
uniform float sunY;
uniform float timer;
uniform float sundirect;
uniform float sunScale; 

float noise( float n )
{
     return fract(sin(n+timer/2.0));
}

//float noise2(vec2 co){
    //return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
//}

vec3 lensflare(vec2 uv,vec2 pos,float sunscale)
{
	vec2 main = uv-pos;
	vec2 uvd = uv*(length(uv));
	
	float ang = atan(main.y, main.x);
	float dist=length(main); dist = pow(dist,.1);
	float n = noise1(vec2((ang-timer/9.0)*16.0,dist*32.0));
	
	float f0 = 1.0/(length(uv-pos)/sunscale+1.0);
	
	f0 = f0+f0*(sin((ang+timer/18.0 + noise1(abs(ang)+n/2.0)*2.0)*12.0)*.1+dist*.1+.8);

	float f2 = max(1.0/(1.0+32.0*pow(length(uvd+0.8*pos),2.0)),.0)*00.25;
	float f22 = max(1.0/(1.0+32.0*pow(length(uvd+0.85*pos),2.0)),.0)*00.23;
	float f23 = max(1.0/(1.0+32.0*pow(length(uvd+0.9*pos),2.0)),.0)*00.21;
	
	vec2 uvx = mix(uv,uvd,-0.5);
	
	float f4 = max(0.01-pow(length(uvx+0.4*pos),2.4),.0)*6.0;
	float f42 = max(0.01-pow(length(uvx+0.45*pos),2.4),.0)*5.0;
	float f43 = max(0.01-pow(length(uvx+0.5*pos),2.4),.0)*3.0;
	
	uvx = mix(uv,uvd,-.4);
	
	float f5 = max(0.01-pow(length(uvx+0.2*pos),5.5),.0)*2.0;
	float f52 = max(0.01-pow(length(uvx+0.4*pos),5.5),.0)*2.0;
	float f53 = max(0.01-pow(length(uvx+0.6*pos),5.5),.0)*2.0;
	
	uvx = mix(uv,uvd,-0.5);
	
	float f6 = max(0.01-pow(length(uvx-0.3*pos),1.6),.0)*6.0;
	float f62 = max(0.01-pow(length(uvx-0.325*pos),1.6),.0)*3.0;
	float f63 = max(0.01-pow(length(uvx-0.35*pos),1.6),.0)*5.0;
	
	vec3 c = vec3(.0);
	
	c.r+=f2+f4+f5+f6; c.g+=f22+f42+f52+f62; c.b+=f23+f43+f53+f63;
	c+=vec3(f0);
	
	return c;
}

void main()
{
    vec4 renderedTex = texture2D(bgl_RenderedTexture, gl_TexCoord[0].st);
    float xconv = bgl_RenderedTextureWidth / bgl_RenderedTextureHeight;
    vec2 sunPos = vec2((sunX - 0.5) * xconv, sunY - 0.5);
    vec2 uv = vec2((gl_TexCoord[0].s - 0.5) * xconv, gl_TexCoord[0].t - 0.5);
    vec3 lens = lensflare(uv, sunPos, sunScale);
    renderedTex.rgb += lens * sundirect;
    gl_FragColor = renderedTex;
}