/** 
 * @file pointLightF.glsl
 *
 * $LicenseInfo:firstyear=2007&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2007, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */
 
#extension GL_ARB_texture_rectangle : enable

/*[EXTRA_CODE_HERE]*/

#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_color;
#else
#define frag_color gl_FragColor
#endif

uniform sampler2DRect diffuseRect;
uniform sampler2DRect specularRect;
uniform sampler2D noiseMap;
uniform sampler2D lightFunc;

uniform vec3 env_mat[3];
uniform float sun_wash;

uniform vec3 color;
uniform float falloff;
uniform float size;

VARYING vec4 vary_fragcoord;
VARYING vec3 trans_center;

uniform vec2 screen_res;

uniform mat4 inv_proj;
uniform vec4 viewport;

vec3 getNorm(vec2 pos_screen);
vec4 getPosition(vec2 pos_screen);
vec3 srgb_to_linear(vec3 c);

uniform float global_light_strength;

void main() 
{
    vec4 frag = vary_fragcoord;
    frag.xyz /= frag.w;
    frag.xyz = frag.xyz*0.5+0.5;
    frag.xy *= screen_res;
    
    vec3 pos = getPosition(frag.xy).xyz;
    vec3 lv = trans_center.xyz-pos;
    float dist = length(lv);
    dist /= size;
    if (dist > 1.0)
    {
        discard;
    }
    
    vec3 norm = getNorm(frag.xy);

    float da = dot(norm, lv);
    if (da < 0.0)
    {
        discard;
    }
    
    lv = normalize(lv);
    da = dot(norm, lv);
    
    float noise = texture2D(noiseMap, frag.xy/128.0).b;
    
    vec3 col = texture2DRect(diffuseRect, frag.xy).rgb;

    float fa = falloff+1.0;
    float dist_atten = clamp(1.0-(dist-1.0*(1.0-fa))/fa, 0.0, 1.0);
    dist_atten *= dist_atten;
    dist_atten *= 2.0;
    
    float lit = da * dist_atten * noise;

    col = color.rgb*lit*col;

    vec4 spec = texture2DRect(specularRect, frag.xy);
    if (spec.a > 0.0)
    {
        lit = min(da*6.0, 1.0) * dist_atten;

        vec3 npos = -normalize(pos);
        vec3 h = normalize(lv+npos);
        float nh = dot(norm, h);
        float nv = dot(norm, npos);
        float vh = dot(npos, h);
        float sa = nh;
        float fres = pow(1 - dot(h, npos), 5) * 0.4+0.5;
        float gtdenom = 2 * nh;
        float gt = max(0,(min(gtdenom * nv / vh, gtdenom * da / vh)));

        if (nh > 0.0)
        {
            float scol = fres*texture2D(lightFunc, vec2(nh, spec.a)).r*gt/(nh*da);
            col += lit*scol*color.rgb*spec.rgb;
        }
    }
    
    if (dot(col, col) <= 0.0)
    {
        discard;
    }
    col *= global_light_strength;
    frag_color.rgb = col;   
    frag_color.a = 0.0;
}
