OpenSpace/modules/globebrowsing/shaders/interpolate_fs.glsl

/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2021                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
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 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
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 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
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 ****************************************************************************************/

#include "fragment.glsl"

uniform sampler2D prevTexture;
uniform sampler2D nextTexture;
uniform sampler2D colormapTexture;
uniform float blendFactor;

in vec2 texCoord;

Fragment getFragment() {
  vec4 texel0 = texture2D(prevTexture, texCoord);
  vec4 texel1 = texture2D(nextTexture, texCoord);

  vec4 mixedTexture = mix(texel0, texel1, blendFactor);

  Fragment frag;  
  if (mixedTexture.r > 0.999) {
    vec2 position = vec2(mixedTexture.r - 0.01, 0.5);
    frag.color = texture2D(colormapTexture, position);
  }
  else {
    vec2 position = vec2(mixedTexture.r , 0.5);
    frag.color = texture2D(colormapTexture, position);
  }

  frag.color.a = mixedTexture.a;
  return frag;
}