star.vfl

/* Name : star.vfl
 * Modifed By : 정현준
 * Shader 소개 : 별모양 패턴 shader 입니다.
 */

#include <math.h>

#pragma label starNum NumberStarPoints
#pragma label transX TransformU
#pragma label transY TransformV
#pragma label min InnterSize
#pragma label max OuterSize
#pragma label rotAngle RotateStar
#pragma label RepeatS RepeatU
#pragma label RepeatT RepeatV
#pragma label bgColor BackGroundColor
#pragma label starColor StarColor

#pragma hint bgColor color
#pragma hint starColor color

surface hjcStar(
    int starNum = 5; // star 꼭지점 갯수
    float transX = 0.5, // star U(s) 위치
    transY = 0.5, // star (v) 위치
    min = 0.145, // star의 안쪽부분 시작점
    max = 0.341, // star의 바깥부분 시작점
    rotAngle = 37.0, // star 회전
    RepeatS = 0.2, // star U(s) 패턴반복
    RepeatT = 0.2; // star U(t) 패턴반복
    vector bgColor = {0, 0, 0.5}, // background 색상
    starColor = {1, 1, 1}; // star 색상
)
{
    float ss, tt, xPos = P.x, yPos = P.y;
    float angle, rad, tempAngle, bias, starAngle;
    vector tempP1, tempP2, resVec1, resVec2, crossTemp;

    starAngle = 2 * PI / starNum; //  2*PI = 360 / 꼭지점 갯수 -> 별 shape
    tempP1 = {1, 0, 0}; 
    tempP2 = set( cos(starAngle / 2), sin( starAngle / 2),0);
    tempP1 *= max;
    tempP2 *= min;

    resVec1 = tempP2 - tempP1;
    
    ss = (xPos * RepeatS)%1 - transX;
    tt = (yPos * RepeatT)%1 - transY;
    angle = atan2(ss, tt) + PI/180 * (-rotAngle);
    
    rad = sqrt(pow(ss, 2) + pow(tt, 2));
    tempAngle = angle% starAngle/starAngle;
    
    if (tempAngle  >= 0.5)
    {
        tempAngle  = 1 - tempAngle ;
    }

    resVec2 = set(cos(tempAngle), sin(tempAngle), 0);
    resVec2 *= rad;
    resVec2 -= tempP1;
    
    crossTemp = cross(resVec1, resVec2);

    if(crossTemp.z < 0)
    {
        bias = 0.0;
    }
    else
    {
        bias = 1.0;
    }

    Cf = lerp(bgColor, starColor, bias);
}