/** 
 * @file class1\deferred\terrainF.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
 * $/LicenseInfo$
 */
 
/*[EXTRA_CODE_HERE]*/

#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_data[3];
#else
#define frag_data gl_FragData
#endif

uniform sampler2D detail_0;
uniform sampler2D detail_1;
uniform sampler2D detail_2;
uniform sampler2D detail_3;
uniform sampler2D alpha_ramp;

VARYING vec3 pos;
VARYING vec3 vary_normal;
VARYING vec4 vary_texcoord0;
VARYING vec4 vary_texcoord1;

vec2 encode_normal(vec3 n);

#ifdef WATER_FOG
vec4 applyWaterFogView(vec3 pos, vec4 c);
#endif

void main()
{
    /// Note: This should duplicate the blending functionality currently used for the terrain rendering.
    
    vec4 color0 = texture2D(detail_0, vary_texcoord0.xy);
    vec4 color1 = texture2D(detail_1, vary_texcoord0.xy);
    vec4 color2 = texture2D(detail_2, vary_texcoord0.xy);
    vec4 color3 = texture2D(detail_3, vary_texcoord0.xy);

    float alpha1 = texture2D(alpha_ramp, vary_texcoord0.zw).a;
    float alpha2 = texture2D(alpha_ramp,vary_texcoord1.xy).a;
    float alphaFinal = texture2D(alpha_ramp, vary_texcoord1.zw).a;
    vec4 outColor = mix( mix(color3, color2, alpha2), mix(color1, color0, alpha1), alphaFinal );
   
    outColor.a = 0.0; // yes, downstream atmospherics 
#ifdef WATER_FOG
    outColor = applyWaterFogView(pos.xyz, outColor);
    outColor.a = 1.0; // no downstream atmo
#endif
    
    frag_data[0] = outColor;
    frag_data[1] = vec4(0.0,0.0,0.0,-1.0);
    vec3 nvn = normalize(vary_normal);
    frag_data[2] = vec4(encode_normal(nvn.xyz), 0.0, 0.0);
}