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/**
* @file pbrTerrainBakeF.glsl
*
* $LicenseInfo:firstyear=2007&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2024, 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]*/
out vec4 frag_color;
struct TerrainMix
{
vec4 weight;
int type;
};
TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal);
uniform sampler2D alpha_ramp;
// vary_texcoord* are used for terrain composition
in vec4 vary_texcoord0;
in vec4 vary_texcoord1;
void main()
{
TerrainMix tm;
float alpha1 = texture(alpha_ramp, vary_texcoord0.zw).a;
float alpha2 = texture(alpha_ramp,vary_texcoord1.xy).a;
float alphaFinal = texture(alpha_ramp, vary_texcoord1.zw).a;
tm = get_terrain_mix_weights(alpha1, alpha2, alphaFinal);
// tm.weight.x can be ignored. The paintmap saves a channel by not storing
// swatch 1, and assuming the weights of the 4 swatches add to 1.
// TERRAIN_PAINT_PRECISION emulates loss of precision at lower bit depth
// when a corresponding low-bit image format is not available. Because
// integral values at one depth cannot be precisely represented at another
// bit depth, rounding is required. To maximize numerical stability for
// future conversions, bit depth conversions should round to the nearest
// integer, not floor or ceil.
frag_color = max(vec4(round(tm.weight.yzw * TERRAIN_PAINT_PRECISION) / TERRAIN_PAINT_PRECISION, 1.0), vec4(0));
}
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