Lib Env - Shader API

import lib-defines.glsl

//: param auto texture_environment

uniform sampler2D environment_texture;

//: param auto environment_rotation

uniform float environment_rotation;

//: param auto environment_exposure

uniform float environment_exposure;

//: param auto environment_irrad_mat_red

uniform mat4 irrad_mat_red;

//: param auto environment_irrad_mat_green

uniform mat4 irrad_mat_green;

//: param auto environment_irrad_mat_blue

uniform mat4 irrad_mat_blue;

vec3 envSampleLOD(vec3 dir, float lod)

{

  // WORKAROUND: Intel GLSL compiler for HD5000 is bugged on OSX:

  // https://bugs.chromium.org/p/chromium/issues/detail?id=308366

  // It is necessary to replace atan(y, -x) by atan(y, -1.0 * x) to force

  // the second parameter to be interpreted as a float

  vec2 pos = M_INV_PI * vec2(atan(-dir.z, -1.0 * dir.x), 2.0 * asin(dir.y));

  pos = 0.5 * pos + vec2(0.5);

  pos.x += environment_rotation;

  return textureLod(environment_texture, pos, lod).rgb * environment_exposure;

}

vec3 envIrradiance(vec3 dir)

{

  float rot = environment_rotation * M_2PI;

  float crot = cos(rot);

  float srot = sin(rot);

  vec4 shDir = vec4(dir.xzy, 1.0);

  shDir = vec4(

    shDir.x * crot - shDir.y * srot,

    shDir.x * srot + shDir.y * crot,

    shDir.z,

    1.0);

  return max(vec3(0.0), vec3(

      dot(shDir, irrad_mat_red * shDir),

      dot(shDir, irrad_mat_green * shDir),

      dot(shDir, irrad_mat_blue * shDir)

    )) * environment_exposure;

}