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

export const lightingUniformsWGSL = /* wgsl */ `\
// #if (defined(SHADER_TYPE_FRAGMENT) && defined(LIGHTING_FRAGMENT)) || (defined(SHADER_TYPE_VERTEX) && defined(LIGHTING_VERTEX))
struct AmbientLight {
  color: vec3<f32>,
};

struct PointLight {
  color: vec3<f32>,
  position: vec3<f32>,
  attenuation: vec3<f32>, // 2nd order x:Constant-y:Linear-z:Exponential
};

struct DirectionalLight {
  color: vec3<f32>,
  direction: vec3<f32>,
};

struct lightingUniforms {
  enabled: i32,
  pointLightCount: i32,
  directionalLightCount: i32,

  ambientColor: vec3<f32>,

  // TODO - support multiple lights by uncommenting arrays below
  lightType: i32,
  lightColor: vec3<f32>,
  lightDirection: vec3<f32>,
  lightPosition: vec3<f32>,
  lightAttenuation: vec3<f32>,

  // AmbientLight ambientLight;
  // PointLight pointLight[MAX_LIGHTS];
  // DirectionalLight directionalLight[MAX_LIGHTS];
};

// Binding 0:1 is reserved for lighting (Note: could go into separate bind group as it is stable across draw calls)
@binding(1) @group(0) var<uniform> lighting : lightingUniforms;

fn lighting_getPointLight(index: i32) -> PointLight {
  return PointLight(lighting.lightColor, lighting.lightPosition, lighting.lightAttenuation);
}

fn lighting_getDirectionalLight(index: i32) -> DirectionalLight {
  return DirectionalLight(lighting.lightColor, lighting.lightDirection);
} 

fn getPointLightAttenuation(pointLight: PointLight, distance: f32) -> f32 {
  return pointLight.attenuation.x
       + pointLight.attenuation.y * distance
       + pointLight.attenuation.z * distance * distance;
}
`;