shader_type spatial;
render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_burley, specular_schlick_ggx, unshaded;
stencil_mode write, compare_less_or_equal, 1;

uniform vec4 albedo : source_color;
uniform sampler2D texture_albedo : source_color, filter_linear_mipmap, repeat_enable;

uniform bool useNormalMap = false;
uniform bool flipNormalMapZ = true;
uniform sampler2D texture_normal : filter_linear_mipmap, repeat_enable;

uniform float uvScale;
uniform float uvOffset;
uniform float uvSpeed;

uniform vec2 highlightDirection1;
uniform float highlightSharpness1: hint_range(0.0, 1.0) = 0.9;
uniform float highlightSize1: hint_range(0.0, 1.0) = 0.1;

uniform vec2 highlightDirection2;
uniform float highlightSharpness2: hint_range(0.0, 1.0) = 0.9;
uniform float highlightSize2: hint_range(0.0, 1.0) = 0.1;

varying float albedoU;

void vertex() 
{
	albedoU = VERTEX.y * uvScale + uvOffset + uvSpeed * TIME;
}

vec3 computeNormal(  vec3 t, vec3 b, vec3 n, vec2 _UV )
{
  vec3 sampledNormal = texture( texture_normal, _UV ).xyz * 2.0 - 1.0;  
  
  if ( flipNormalMapZ )
  {
    sampledNormal.z *= -1.0;
  }
  return normalize( mat3( t, b, n ) * sampledNormal );  
}

float computeHighlight( vec3 lightDirection, vec3 _NORMAL, float size, float sharpness )
{
  float invSize = 1.0 - pow( size, 3 );
  float invSharpness = 1.0 - pow( sharpness, 0.1 );
  float lowerEdge = invSize - invSharpness;
  float upperEdge = invSize + invSharpness;
  
  return smoothstep( lowerEdge, upperEdge, dot( _NORMAL, normalize( lightDirection ) ) );
}

void fragment() 
{
	vec2 base_uv = UV;

	vec4 albedo_tex = texture(texture_albedo, vec2( albedoU, 0.0 ));
	ALBEDO = albedo.rgb * albedo_tex.rgb;
  
  vec3 combinedNormal = NORMAL;
  
  if ( useNormalMap )
  {
    combinedNormal = computeNormal( TANGENT, BINORMAL, NORMAL, UV );
  }
  
  float highlight1 = computeHighlight( vec3( highlightDirection1, 1.0 ), combinedNormal, highlightSize1, highlightSharpness1 ); 
  float highlight2 = computeHighlight( vec3( highlightDirection2, 1.0 ), combinedNormal, highlightSize2, highlightSharpness2 ); 
  
  float highlightsCombined = max( highlight1, highlight2 );
  ALBEDO = mix( ALBEDO, vec3( 1.0 ), highlightsCombined );

}