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

export const LAMBERT_VS = /* glsl */ `\
layout(std140) uniform lambertMaterialUniforms {
  uniform bool unlit;
  uniform float ambient;
  uniform float diffuse;
} material;
`;

export const LAMBERT_FS = /* glsl */ `\
layout(std140) uniform lambertMaterialUniforms {
  uniform bool unlit;
  uniform float ambient;
  uniform float diffuse;
} material;

vec3 lighting_getLightColor(vec3 surfaceColor, vec3 light_direction, vec3 normal_worldspace, vec3 color) {
  float lambertian = max(dot(light_direction, normal_worldspace), 0.0);
  return lambertian * material.diffuse * surfaceColor * color;
}

vec3 lighting_getLightColor(vec3 surfaceColor, vec3 cameraPosition, vec3 position_worldspace, vec3 normal_worldspace) {
  vec3 lightColor = surfaceColor;

  if (material.unlit) {
    return surfaceColor;
  }

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

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

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

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

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

  return lightColor;
}
`;