SDF_005

/** ******************************************************** ***



    SOURCE_____CODE : tinyurl.com/SDF-005



    FILE_______NAME : SDF_005._
    PASTEBIN__TITLE : SDF_005
    PASTEBIN____URL : https://pastebin.com/NW1vAsaA
    TWITCH______URL : www.twitch.com/kanjicoder
    TWITTER_____URL : twitter.com/MakeGamesHappen
    DESMOS____GRAPH : NO GRAPHS TODAY

*** ******************************************************** **/

#define MAX_STE ( 100   )
#define MIN_DIS ( 0.02  )
#define MAX_DIS ( 100.0 )

    #define I32 int
    #define _ 0
    #define X 1
    I32 til_arr[ 25 * 7 ]=I32[ 25 * 7 ](
    _,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,
    X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X
    );
    #undef  _
    #undef  X
    #undef  I32

float sdf_Sphere( vec3 org_geo , vec3 pop ){

    vec4  obj = vec4( org_geo    ,0.5 ); //: w == radius
    float dis = length( obj.xyz - pop.xyz ) - obj.w;
    return( dis );

}

float sdf_Scene( vec3 org, vec3 ray, vec3 pop ){

    vec3 org_geo = vec3( 4.0,0,0 );

    //:return( sdf_Sphere( org_geo , pop ) );

    //:Only works for orthographic camera. Niave Calc.\
    //:Must convert [ u_v ] back to frag coords.
    float    p_x  = ( org.x * iResolution.y );
    float    p_y  = ( org.y * iResolution.y );


    //: tpW : tile_wid_in_pixels
    //: tpH : tile_hig_in_pixels
    int ntX    = 25; //:Number_Of_Tiles:X-axis
    int ntY    =  7; //:Number_Of_tiles:Y-axis
    int tpW    = int( iResolution.x / float( ntX )  );
    int tpH    = int( iResolution.y / float( ntY )  );
    int tile_x = int( p_x / float( tpW )  );
    int tile_y = int( p_y / float( tpH )  );


    if( tile_x < 0 || tile_x >= 25 ||
        tile_y < 0 || tile_y >=  7
    ){  //:Out Of Bounds
        return( MAX_DIS + 100.00 );
    }else{



        int dex_til = tile_x + ( ntX * tile_y);
        int tile_value = til_arr[ dex_til ];
        if( tile_value > int(0) ){

            float    f_tpW = 1.0;
            float    f_tpH = 1.0;
            float f_tile_x = float(tile_x);
            float f_tile_y = float(tile_y);

            org_geo.x = float( ( f_tile_x * f_tpW ) + (f_tpW/2.0) );
            org_geo.y = float( ( f_tile_y * f_tpH ) + (f_tpH/2.0) );
            org_geo.z = float(                  0                 );

            return( sdf_Sphere( org_geo , pop ) );

        }else{
            //: NO GEOMETRY IN CELL
            //return( MAX_DIS + 100.00 );
          //  return( sdf_Sphere( org_geo , pop ) );
        };;

    };;




}

vec3 sdf_EstNorm( vec3 org, vec3 ray, vec3 pop ){

    #define  S sdf_Scene
    #define  E 0.0001
    #define  X pop.x
    #define  Y pop.y
    #define  Z pop.z
    #define  O org
    #define  R ray
    return( normalize(vec3(

        S(O,R,vec3(X+E,Y  ,Z  ))  -  S(O,R,vec3(X-E,Y  ,Z  ))
    ,   S(O,R,vec3(X  ,Y+E,Z  ))  -  S(O,R,vec3(X  ,Y-E,Z  ))
    ,   S(O,R,vec3(X  ,Y  ,Z+E))  -  S(O,R,vec3(X  ,Y  ,Z-E))

    )));;;
    #undef   S
    #undef   E
    #undef   X
    #undef   Y
    #undef   Z
    #undef   O
    #undef   R
}

vec4 sdf_Render( vec3 org , vec3 ray ){

    /** 1: Ray March           **/
    /** 2: Calculate Lighting  **/

    vec3   pop; //:point_on_path
    float  d_o; //:distance_from_origin
    float  d_s; //:distance_from_surface

    d_o = 0.0;

    for( int i = 0; i <= MAX_STE ; i++ ){

        pop = org + ( ray * d_o );
        d_s = sdf_Scene( org,ray,  pop );

        if( d_s <= MIN_DIS || d_o >= MAX_DIS ){
            break;
        };;

        d_o += ( d_s ); //:March forward by[ d_s ].
    };;

    float hit = max(0.0,min(1.0,( 1.0 - d_s )));

    vec3   l_p = vec3(cos(iTime*1.0)*100.0,0,20.0); //:light_pos
    vec3   l_n = normalize( l_p - pop );
    vec3   s_n = sdf_EstNorm( org,ray,pop );
    float  g_i = 0.1; //:global_illumination
    float  l_i = dot( l_n , s_n ); //:light_intensity.
    vec3   l_t = vec3( 0 ); //:light_tuple

    l_t.x =( l_i + g_i );
    l_t.y =( l_i + 0.0 );
    l_t.z =( l_i + 0.0 );


    return( vec4( vec3( hit * l_t.xyz ) , hit ));

}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{

    vec2   u_v = (fragCoord-0.5*iResolution.xy)/iResolution.yy;


    //:    ray: Orthographic Camera Ray
    vec3   ray = normalize( vec3( u_v.x , u_v.y , 0 - 1 ) );
    vec3   org =            vec3( u_v.x , u_v.y , 0 + 9 );

    vec4   col = sdf_Render( org , ray );


    fragColor = col;
}