atari df

atari.glsl

#define RESOLUTION  resolution
#define PI          3.141592654
#define TAU         (2.0*TAU)

// IQ's polynomial min
float pmin(float a, float b, float k) {
  float h = clamp(0.5+0.5*(b-a)/k, 0.0, 1.0);
  return mix(b, a, h) - k*h*(1.0-h);
}

float pmax(float a, float b, float k) {
  return -pmin(-a, -b, k);
}

float pabs(float a, float k) {
  return pmax(a, -a, k);
}

float circle(vec2 p, float r) {
  return length(p) - r;
}

float isosceles(vec2 p, vec2 q) {
  p.x = abs(p.x);
  vec2 a = p - q*clamp( dot(p,q)/dot(q,q), 0.0, 1.0 );
  vec2 b = p - q*vec2( clamp( p.x/q.x, 0.0, 1.0 ), 1.0 );
  float s = -sign( q.y );
  vec2 d = min( vec2( dot(a,a), s*(p.x*q.y-p.y*q.x) ),
                vec2( dot(b,b), s*(p.y-q.y)  ));
  return -sqrt(d.x)*sign(d.y);
}

float box(vec2 p, vec2 b) {
  vec2 d = abs(p)-b;
  return length(max(d,0.0)) + min(max(d.x,d.y),0.0);
}

float horseshoe(vec2 p, vec2 c, float r, vec2 w) {
  p.x = abs(p.x);
  float l = length(p);
  p = mat2(-c.x, c.y, 
            c.y, c.x)*p;
  p = vec2((p.y>0.0)?p.x:l*sign(-c.x),
           (p.x>0.0)?p.y:l );
  p = vec2(p.x,abs(p.y-r))-w;
  return length(max(p,0.0)) + min(0.0,max(p.x,p.y));
}

float segment(vec2 p, vec2 a, vec2 b) {
  vec2 pa = p-a, ba = b-a;
  float h = clamp( dot(pa,ba)/dot(ba,ba), 0.0, 1.0 );
  return length( pa - ba*h );
}

float atari_a(inout vec2 p, vec2 off) {
  p -= vec2(0.275, 0.0);

  float d0 = isosceles(p*vec2(1.0, -1.0)-vec2(0.0, -0.225), vec2(0.20, 0.65))-0.1;
  float d1 = isosceles(p*vec2(1.0, -1.0)-vec2(0.0, -0.18), vec2(0.13, 0.55))-0.005;
  float d2 = box(p-vec2(0.0, -0.135), vec2(0.15, 0.06));
  float d3 = p.y+0.325;

  float d = d0;
  d = max(d, -d1);
  d = pmin(d, d2, 0.0125);
  d = pmax(d, -d3, 0.0125);

  p -= vec2(0.275, 0.0) + off;

  return d;
}

float atari_i(inout vec2 p, vec2 off) {
  p -= vec2(0.07, 0.0);

  float d0 = box(p, vec2(0.07, 0.325)-0.0125)-0.0125;

  float d = d0;

  p -= vec2(0.07, 0.0) + off;
  return d;
}

float atari_r(inout vec2 p, vec2 off) {
  p -= vec2(0.22, 0.0);

  float d0 = p.y+0.325;
  float d1 = box(p - vec2(-0.12, -0.075), vec2(0.0, 0.30))-0.1;
  const float a = PI/2;
  const vec2 c = vec2(cos(a), sin(a));
  vec2 hp = p;
  hp -= vec2(0.0, 0.14);
  hp.xy = -hp.yx;
  float d2 = horseshoe(hp, c, 0.125, 0.2175*vec2(0.5,0.275));
  float d3 = segment(p-vec2(-0.015, 0.005), vec2(0.0), vec2(0.22, -0.4))-0.07;
  float d4 = box(p-vec2(-0.05, -0.152), vec2(0.03, 0.35))-0.0075;
  
  float d = d1;
  d = min(d, d2);
  d = max(d, -d4);
  d = min(d, d3);
  d = pmax(d, -d0, 0.0125);
  
  p -= vec2(0.25, 0.0)+off;
  
  return d;
}

float atari_t(inout vec2 p, vec2 off) {
  p -= vec2(0.195, 0.0);

  float d0 = box(p - vec2(0.0, 0.265), vec2(0.195, 0.06)-0.0125)-0.0125;
  float d1 = box(p - vec2(0.0, -0.03), vec2(0.07, 0.295)-0.0125)-0.0125;
  
  float d = d0;
  d = pmin(d, d1, 0.0125);
  
  p -= vec2(0.195, 0.0) + off;
  
  return d;
}

float atari_text(vec2 p) {
  p -= vec2(-1.0, 0.0);
  float d = 1E6;
  d = min(d, atari_a(p, vec2(-0.075, 0.0)));
  d = min(d, atari_t(p, vec2(-0.055, 0.0)));
  d = min(d, atari_a(p, vec2(0.02, 0.0)));
  d = min(d, atari_r(p, vec2(0.01, 0.0)));
  d = min(d, atari_i(p, vec2(0.0, 0.0)));
  return d;
}

float df(vec2 p) {
  const float z = 0.5;
  float da = atari_text(p/z)*z;
  
  return da;
}

void main(void) {
  vec2 q = inData.v_texcoord;
  vec2 p = -1. + 2. * q;
  p.x *= RESOLUTION.x/RESOLUTION.y;
  float aa = 2.0/RESOLUTION.y;
  float d = df(p);
  
  vec2 tp = p;
  tp -= vec2(-0.04, 0.21);
  tp *= 1;
  tp.y *= -1;
  tp += 0.5;
  vec4 tcol = texture(texture0, tp);
  
  vec3 col = vec3(0.1);
//  col = mix(col, tcol.xyz, tcol.w);

  vec3 acol = mix(col, vec3(1.0), 0.5);

  col = mix(col, acol, smoothstep(-aa, aa, -d));
  col += vec3(0.5, 0.0, 0.0)*sin(300*d) ;
  fragColor = vec4(col, 1.0);
}