// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

export const lightingUniformsGLSL = /* glsl */ `\
precision highp int;

// #if (defined(SHADER_TYPE_FRAGMENT) && defined(LIGHTING_FRAGMENT)) || (defined(SHADER_TYPE_VERTEX) && defined(LIGHTING_VERTEX))
struct AmbientLight {
  vec3 color;
};

struct PointLight {
  vec3 color;
  vec3 position;
  vec3 attenuation; // 2nd order x:Constant-y:Linear-z:Exponential
};

struct SpotLight {
  vec3 color;
  vec3 position;
  vec3 direction;
  vec3 attenuation;
  vec2 coneCos;
};

struct DirectionalLight {
  vec3 color;
  vec3 direction;
};

struct UniformLight {
  vec3 color;
  vec3 position;
  vec3 direction;
  vec3 attenuation;
  vec2 coneCos;
};

layout(std140) uniform lightingUniforms {
  int enabled;
  int directionalLightCount;
  int pointLightCount;
  int spotLightCount;
  vec3 ambientColor;
  UniformLight lights[5];
} lighting;

PointLight lighting_getPointLight(int index) {
  UniformLight light = lighting.lights[index];
  return PointLight(light.color, light.position, light.attenuation);
}

SpotLight lighting_getSpotLight(int index) {
  UniformLight light = lighting.lights[lighting.pointLightCount + index];
  return SpotLight(light.color, light.position, light.direction, light.attenuation, light.coneCos);
}

DirectionalLight lighting_getDirectionalLight(int index) {
  UniformLight light =
    lighting.lights[lighting.pointLightCount + lighting.spotLightCount + index];
  return DirectionalLight(light.color, light.direction);
}

float getPointLightAttenuation(PointLight pointLight, float distance) {
  return pointLight.attenuation.x
       + pointLight.attenuation.y * distance
       + pointLight.attenuation.z * distance * distance;
}

float getSpotLightAttenuation(SpotLight spotLight, vec3 positionWorldspace) {
  vec3 light_direction = normalize(positionWorldspace - spotLight.position);
  float coneFactor = smoothstep(
    spotLight.coneCos.y,
    spotLight.coneCos.x,
    dot(normalize(spotLight.direction), light_direction)
  );
  float distanceAttenuation = getPointLightAttenuation(
    PointLight(spotLight.color, spotLight.position, spotLight.attenuation),
    distance(spotLight.position, positionWorldspace)
  );
  return distanceAttenuation / max(coneFactor, 0.0001);
}

// #endif
`;