OpenSpace/modules/spacecraftinstruments/shaders/renderableModelProjection_fs.glsl

/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2025                                                               *
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#version __CONTEXT__

in vec4 vs_ndc;
in vec4 vs_normal;

layout (location = 0) out vec4 color;
// Even though the stencil texture is only a single channel, we still need to
// output a vec4, or the result will disappear
layout (location = 1) out vec4 stencil;

uniform sampler2D projectionTexture;
uniform sampler2D depthTexture;
uniform bool needShadowMap;
uniform vec3 boresight;


bool inRange(float x, float a, float b) {
  return (x >= a && x <= b);
}


void main() {
  vec3 n = normalize(vs_normal.xyz);
  vec2 uv = vec2(0.5) * vs_ndc.xy + vec2(0.5);

  if (needShadowMap) {
    float thisDepth = vs_ndc.z * 0.5 + 0.5;
    float closestDepth = texture(depthTexture, uv).r;
    const float epsilon = 0.001;

    if (inRange(uv.x, 0.0, 1.0) && inRange(uv.y, 0.0, 1.0) &&
        dot(n, boresight) < 0 && thisDepth <= closestDepth + epsilon)
    {
      color = texture(projectionTexture, vec2(1.0) - uv);
      color.a = 1.0;
      stencil = vec4(1.0);
    }
    else {
      discard;
    }
  }
  else {
    if (inRange(uv.x, 0.0, 1.0) && inRange(uv.y, 0.0, 1.0) && dot(n, boresight) < 0) {
      color = texture(projectionTexture, vec2(1.0) - uv);
      color.a = 1.0;
      stencil = vec4(1.0);
    }
    else {
      discard;
    }
  }
}