// 2D Signed Distance equations by InigoQuilez

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform int shape;
uniform int bg;
uniform int aa;
uniform int sides;
uniform int tile;

uniform int  drawDF;
uniform vec2 dfLevel;

uniform float rotation;
uniform float angle;
uniform float inner;
uniform float outer;
uniform float corner;

uniform float stRad;
uniform float edRad;

uniform vec2 angle_range;

uniform vec2 dimension;
uniform vec2 center;
uniform vec2 scale;

uniform vec4 bgColor;

#define PI  3.14159265359
#define TAU 6.283185307179586

float sdRegularPolygon(in vec2 p, in float r, in int n, in float ang ) { #region
    // these 4 lines can be precomputed for a given shape
    float an = PI / float(n);
    vec2  acs = vec2(cos(an), sin(an));

    // reduce to first sector
    float bn = mod(atan(p.x, p.y) + PI - ang, 2.0 * an) - an;
    p = length(p) * vec2(cos(bn), abs(sin(bn)));

    // line sdf
    p -= r * acs;
    p.y += clamp( -p.y, 0.0, r * acs.y);
    return length(p) * sign(p.x);
} #endregion

// signed distance to a n-star polygon with external angle en
float sdStar(in vec2 p, in float r, in int n, in float m, in float ang) { #region m=[2,n]
    // these 4 lines can be precomputed for a given shape
    float an = PI / float(n);
    float en = PI / m;
    vec2  acs = vec2(cos(an), sin(an));
    vec2  ecs = vec2(cos(en), sin(en)); // ecs=vec2(0,1) and simplify, for regular polygon,

    // reduce to first sector
    float bn = mod( atan(p.x, p.y) + PI - ang, 2.0 * an) - an;
    p = length(p) * vec2(cos(bn), abs(sin(bn)));

    // line sdf
    p -= r * acs;
    p += ecs * clamp( -dot(p, ecs), 0.0, r * acs.y / ecs.y);
    return length(p)*sign(p.x);
} #endregion

// sca is the sin/cos of the orientation
// scb is the sin/cos of the aperture
float sdArc( in vec2 p, in vec2 sca, in vec2 scb, in float ra, in float rb ) { #region
    p *= mat2(sca.x, sca.y, -sca.y, sca.x);
    p.x = abs(p.x);
    float k = (scb.y * p.x > scb.x * p.y) ? dot(p.xy,scb) : length(p);
    return sqrt( dot(p, p) + ra * ra - 2.0 * ra * k ) - rb;
} #endregion

float sdRoundBox( in vec2 p, in vec2 b, in vec4 r ) { #region
    r.xy = (p.x > 0.0)? r.xy : r.zw;
    r.x  = (p.y > 0.0)? r.x  : r.y;
    vec2 q = abs(p) - b + r.x;
    return min(max(q.x, q.y), 0.0) + length(max(q, 0.0)) - r.x;
} #endregion

float sdBox( in vec2 p, in vec2 b ) { #region
    vec2 d = abs(p) - b;
    return length(max(d, 0.0)) + min(max(d.x, d.y), 0.0);
} #endregion

float sdTearDrop( vec2 p, float r1, float r2, float h ) { #region
    p.x = abs(p.x);
    float b = (r1-r2)/h;
    float a = sqrt(1.0-b*b);
    float k = dot(p,vec2(-b,a));
    if( k < 0.0 ) return length(p) - r1;
    if( k > a*h ) return length(p-vec2(0.0,h)) - r2;
    return dot(p, vec2(a,b) ) - r1;
} #endregion

float sdCross( in vec2 p, in vec2 b, float r ) { #region
    p = abs(p); p = (p.y>p.x) ? p.yx : p.xy;
    vec2  q = p - b;
    float k = max(q.y,q.x);
    vec2  w = (k>0.0) ? q : vec2(b.y-p.x,-k);
    return sign(k)*length(max(w,0.0)) + r;
} #endregion

float sdVesica(vec2 p, float r, float d) { #region
    p = abs(p);

    float b = sqrt(r*r-d*d);  // can delay this sqrt by rewriting the comparison
    return ((p.y-b)*d > p.x*b) ? length(p-vec2(0.0,b))*sign(d)
                               : length(p-vec2(-d,0.0))-r;
} #endregion

float sdCrescent(vec2 p, float s, float c, float a) { #region
	float o = length(p) - 1.;
	float i = length(p - vec2(cos(a) * (1. - s * c), sin(a) * (1. - s * c))) / s - 1.;
	
	return max(o, -i);
} #endregion

float sdDonut(vec2 p, float s) { #region
	float o = length(p) - 1.;
	float i = length(p) / s - 1.;
	
	return max(o, -i);
} #endregion

void main() {
	float color = 0.;
	vec2  coord = (v_vTexcoord - center) * mat2(cos(rotation), -sin(rotation), sin(rotation), cos(rotation)) / scale;
	vec2  ratio = dimension / dimension.y;
	float d;
	
	if(tile == 1) coord = mod(coord + 1., 2.) - 1.;
	
	if(shape == 0) {
		d = sdBox( (v_vTexcoord - center) * mat2(cos(rotation), -sin(rotation), sin(rotation), cos(rotation)) * ratio, (scale * ratio - corner));
		d -= corner;
	} else if(shape == 1) {
		d = length(coord) - 1.;
	} else if(shape == 2) {
		d = sdRegularPolygon( coord, 0.9 - corner, sides, angle );
		d -= corner;
	} else if(shape == 3) {
	    d = sdStar( coord, 0.9 - corner, sides, 2. + inner * (float(sides) - 2.), angle );
		d -= corner;
	} else if(shape == 4) d = sdArc( coord, vec2(sin(angle), cos(angle)), angle_range, 0.9 - inner, inner );
	else if(shape == 5)   d = sdTearDrop( coord + vec2(0., 0.5), stRad, edRad, 1. );
	else if(shape == 6)   d = sdCross( coord, vec2(1. + corner, outer), corner );
	else if(shape == 7)   d = sdVesica( coord, inner, outer );
	else if(shape == 8)   d = sdCrescent( coord, inner, outer, angle );
	else if(shape == 9)   d = sdDonut( coord, inner );
	
	if(drawDF == 1) {
		color = -d;
		color = (color - dfLevel.x) / (dfLevel.y - dfLevel.x);
	} else if(aa == 0)
		color = step(d, 0.0);
	else
		color = smoothstep(0.02, -0.02, d);
	
	gl_FragColor = mix(bgColor, v_vColour, color);
}