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

export const LAMBERT_WGSL = /* wgsl */ `\
struct lambertMaterialUniforms {
  unlit: u32,
  ambient: f32,
  diffuse: f32,
};

@group(3) @binding(auto) var<uniform> lambertMaterial : lambertMaterialUniforms;

fn lighting_getLightColor(surfaceColor: vec3<f32>, light_direction: vec3<f32>, normal_worldspace: vec3<f32>, color: vec3<f32>) -> vec3<f32> {
  let lambertian: f32 = max(dot(light_direction, normal_worldspace), 0.0);
  return lambertian * lambertMaterial.diffuse * surfaceColor * color;
}

fn lighting_getLightColor2(surfaceColor: vec3<f32>, cameraPosition: vec3<f32>, position_worldspace: vec3<f32>, normal_worldspace: vec3<f32>) -> vec3<f32> {
  var lightColor: vec3<f32> = surfaceColor;

  if (lambertMaterial.unlit != 0u) {
    return surfaceColor;
  }

  if (lighting.enabled == 0) {
    return lightColor;
  }

  lightColor = lambertMaterial.ambient * surfaceColor * lighting.ambientColor;

  for (var i: i32 = 0; i < lighting.pointLightCount; i++) {
    let pointLight: PointLight = lighting_getPointLight(i);
    let light_position_worldspace: vec3<f32> = pointLight.position;
    let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
    let light_attenuation = getPointLightAttenuation(
      pointLight,
      distance(light_position_worldspace, position_worldspace)
    );
    lightColor += lighting_getLightColor(
      surfaceColor,
      light_direction,
      normal_worldspace,
      pointLight.color / light_attenuation
    );
  }

  for (var i: i32 = 0; i < lighting.spotLightCount; i++) {
    let spotLight: SpotLight = lighting_getSpotLight(i);
    let light_position_worldspace: vec3<f32> = spotLight.position;
    let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
    let light_attenuation = getSpotLightAttenuation(spotLight, position_worldspace);
    lightColor += lighting_getLightColor(
      surfaceColor,
      light_direction,
      normal_worldspace,
      spotLight.color / light_attenuation
    );
  }

  for (var i: i32 = 0; i < lighting.directionalLightCount; i++) {
    let directionalLight: DirectionalLight = lighting_getDirectionalLight(i);
    lightColor += lighting_getLightColor(
      surfaceColor,
      -directionalLight.direction,
      normal_worldspace,
      directionalLight.color
    );
  }

  return lightColor;
}
`;