ULRE/ShaderLibrary/Std3D/BlinnPhong/SunLightPureColorTexture.mtl

#Material
Name        BlinnPhong+HalfLambert shading model only color
Reference   https://zhuanlan.zhihu.com/p/442023993
Base        Std3D/BlinnPhong

//某些Require并不真的存在.ubo文件，写成一行一个是为了方便未来改成带路径的
Require     LocalToWorld
Require     Camera

define      HAVE_SPECULAR   off     //默认不定义HAVE_SPECULAR

UBO
{
    File    BlinnPhongSun.ubo   //文件名,如果/开头表示从ShaderLibrary根目录开始，没有则表示同一目录
    Struct  BlinnPhongSun       //结构名称
    Name    sun                 //在代码中的变量名
    Stage   Fragment            //会引用的shader
    Set     Global              //Descriptor Set
}

#MaterialInstance
Length 32
Stage  Fragment
Code
{
    vec4 Color;
    uint tex_id;
}

#VertexInput
vec3 Normal
vec2 TexCoord

#Vertex
Output
{
    vec4 Position;
    vec3 Normal;
    vec2 TexCoord
}

Code
{

    void main()
    {
        Output.Normal   =GetNormal();
        Output.Position =GetPosition3D();
        Output.TexCoord =TexCoord;
        
        HandoverMI();

        gl_Position     =Output.Position;
    }
}

#Fragment

sampler2DArray TextureBaseColor

Output
{
    vec4 FragColor;
}

Code
{
    #define HAVE_SPECULAR

    void main()
    {
        MaterialInstance mi=GetMI();

        vec4 texture_color=texture(TextureBaseColor,vec3(Input.TexCoord,mi.tex_id));
        
        //点乘法线和光照
        float intensity=0.5*max(dot(Input.Normal,sun.direction.xyz),0.0)+0.5;

        //直接光颜色
        vec3 direct_color           =intensity*sun.color.rgb*mi.Color.rgb*texture_color.rgb;

    #ifndef HAVE_SPECULAR
        FragColor=vec4(direct_color,1.0);
     #else

        vec3 spec_color=vec3(0.0);

        if(intensity>0.0)
        {
            vec3 half_vector=normalize(sun.direction.xyz+normalize(Input.Position.xyz+camera.pos));

            float specular=max(dot(half_vector,Input.Normal),0.0);

            spec_color=specular*pow(specular,8)*sun.color.rgb;
        }
        
        FragColor=vec4(direct_color+spec_color,1.0);
     #endif//HAVE_SPECULAR
    }
}