Moon Night

OpenGL 레포트였던 밤하늘에 떠있는 달과 별을 그려보았다.

별의 좌표는 랜덤으로 주어지고, 달은 원의 좌표를 계산하여 그렸다.

지형은 일직선을 재귀적으로 쪼개서 각도를 변경하여 그렸다.

void setup(){
    size(300, 240, P2D);
    background(0);

    noLoop();
    noStroke();
}

void draw(){

    drawSky();      
    drawStars(50);      
    drawEclipse();      
    drawMountain(height / 1.5);
}

void drawSky(){

    // gradient
    color night = color(0, 0, 125);
    color glow = color(255, 102, 0);

    for(int i = 0; i < height; i++){
    float rate = map(i, 0, height, 0, 1);
    color c = lerpColor(night, glow, rate);
    stroke(c);
    line(0, i, width, i);
    }
}

void drawStars(int num){

    stroke(255);

    for(int i = 0; i < num; i++){
    int x = random(width);
    int y = random(height / 2);

    point(x, y);
    }
}

void drawEclipse(){

    noStroke();

    color yellow = color(255, 255, 0);    
    fill(yellow);

    int cx = width / 2;
    int cy = width / 4;
    int r = 30;

    beginShape();

    for(int i = -45; i < 135; i++){
    int x = cx + r * cos(radians(i));
    int y = cy + r * sin(radians(i));

    vertex(x, y);
    }

    for(int i = 135; i > -45; i--){        
    int x = cx - 10 + r * cos(radians(i));
    int y = cy - 10 + r * sin(radians(i));

    vertex(x, y);
    }

    endShape(CLOSE);
}

void drawMountain(int tall){

    beginShape();

    vertex(0, height);
    vertex(0, tall);

    breakLine(0, tall, width, tall);

    vertex(width, tall);
    vertex(width, height);

    endShape(CLOSE);
}

void breakLine(int x0, int y0, int x1, int y1){
    float dist = sqrt(pow(x1 - x0, 2) + pow(y1 - y0, 2));

    if(dist < 30){
    return;
    }

    // mid point
    int cx = x0 + (x1 - x0) / 2;
    int cy = y0 + (y1 - y0) / 2;

    int x2 = cx + (dist / 8) * cos(QUARTER_PI * random(8));
    int y2 = cy + (dist / 8) * sin(QUARTER_PI * random(8));

    breakLine(x0, y0, x2, y2);

    vertex(x2, y2);

    breakLine(x2, y2, x1, y1);
}