renderCsm_frag.glsl

#version 120
#extension GL_EXT_texture_array : require
#extension GL_EXT_texture_array : enable

vec2 poissonDisk[36] = vec2[](
        vec2(-0.412506, -0.505401),
        vec2(-0.198678, -0.362386),
        vec2(0.0612825, -0.360698),
        vec2(-0.680803, -0.662816),
        vec2(-0.275453, -0.057909),
        vec2(-0.57524, -0.225002),
        vec2(-0.135255, -0.644076),
        vec2(-0.357393, -0.873324),
        vec2(0.087715, -0.83279),
        vec2(0.274221, -0.575671),
        vec2(0.012977, 0.0652626),
        vec2(-0.908303, -0.306803),
        vec2(-0.632239, 0.236252),
        vec2(-0.972579, 0.0551293),
        vec2(-0.907004, 0.400391),
        vec2(0.26208, -0.129809),
        vec2(0.515364, -0.235511),
        vec2(0.470022, -0.743824),
        vec2(0.62804, -0.459096),
        vec2(0.332402, 0.200743),
        vec2(0.83457, -0.0398735),
        vec2(0.645883, 0.24368),
        vec2(0.367844, 0.453785),
        vec2(0.700306, 0.512157),
        vec2(-0.414574, 0.413026),
        vec2(-0.51206, 0.680345),
        vec2(0.40368, 0.800573),
        vec2(-0.0603344, 0.708574),
        vec2(0.0684587, 0.385982),
        vec2(-0.209951, 0.191194),
        vec2(-0.273511, 0.918154),
        vec2(0.19039, 0.661354),
        vec2(0.511419, 0.0151699),
        vec2(0.962834, -0.256675),
        vec2(0.897324, 0.331031),
        vec2(0.00145936, 0.959284)
);

varying vec4 vPos;
uniform sampler2DArray stex;
uniform vec4 far_d;

void main() {
  int index;
  float fudge;
  float fact;

  if (vPos.y < far_d.x) {
    index = 0;
    fudge = 0.1f / 2048;
    fact = 4;
  } else if (vPos.y < far_d.y) {
    index = 1;
    fudge = 0.2f / 2048;
    fact = 2.9f;
  } else if (vPos.y < far_d.z) {
    index = 2;
    fudge = 0.3f / 2048;
    fact = 1.45f;
  } else {
    index = 3;
    fudge = 0.4f / 2048;
    fact = 0.5f;
  }

  vec4 coord = gl_TextureMatrix[index]*vPos;
  float threshold = coord.z - fudge;
  coord.z = float(index);

  // float coef = (texture2DArray(stex, vec3(coord.xy, index)).x > threshold) ? 1 : 0;
  float coef = 0.0f;

  for (int i = 0; i < 36; i++) {
    vec2 offset = poissonDisk[i] * (fact * 0.001f);
    float sample = texture2DArray(stex, vec3(coord.xy + offset, index)).x;
    if (sample > threshold) coef += 1.0f / 36;
  }

  gl_FragColor = vec4(coef, coef, coef, 1.0f);
}