1 files changed, 31 insertions, 12 deletions

diff --git a/pass1.frag b/pass1.frag
index 8917b61..a6b22e0 100644
--- a/pass1.frag
+++ b/pass1.frag
@@ -9,22 +9,25 @@ layout(location = U_LOC_TIME) uniform float time;
 layout(location = U_LOC_PASS1) uniform sampler2D buf;
 ivec2 res = ivec2(RES_H, RES_V);
 
-const float step = 0.04;
+const float step = 0.03;
 const float turns = 9.0;
 
+const vec3 white = vec3(1.0, 1.0, 1.0);
+const vec3 black = vec3(0.0, 0.0, 0.0);
+
 void main() {
+	color = vec4(black, 0.0);
 	vec2 uv = gl_FragCoord.xy / res.xy;
-	float r = 20.0; // circle radius
-	
-	vec2 norm = (uv - 0.5) * 2.0;
-	norm.x *= float(res.x) / float(res.y); // adjust for aspect ratio
 
-	float offset = time * 7.0;
+	float r = 0.007; // circle radius
+	
+	vec2 gc = (uv - 0.5) * 2.0; // graph coordinates (-1,-1) to (1,1)
+	gc.x *= float(res.x) / float(res.y); // adjust circle aspect ratio
 
-	float mag = 1.3 + 0.5 * sin(2 * time);
-	float size = 0.4 + 0.1 * sin(3 * time);
+	float offset = time * 1.0;
 
-	color = vec4(0.0);
+	float mag = 1.3 + 0.5 * sin(2 * time); // braid ratio
+	float size = 0.4 + 0.1 * sin(3 * time); // total size
 
 	for (float t = 0.0; t < PI_2; t += step) {
 		// <https://www.desmos.com/calculator/e0kq6z1ndd>
@@ -33,11 +36,27 @@ void main() {
 			sin(t) + mag * sin(turns * t + offset)
 		);
 		f *= size;
-		if (length(f - norm) < 0.01) {
-			color = vec4(1.0, 1.0, 1.0, 1.0);
+		if (length(f - gc) < r) {
+			color += vec4(white, 1.0);
 		}
 	}
 
-	color += texture(buf, ((uv - 0.5) * 0.99) + 0.5) * 0.97;
+	// create border
+	if (uv.x < 0.002) color += vec4(white * 0.7, 1.0);
+	if (uv.y < 0.002) color += vec4(white * 0.7, 1.0);
+	if (uv.x > 0.998) color += vec4(white * 0.7, 1.0);
+	if (uv.y > 0.998) color += vec4(white * 0.7, 1.0);
+	
+	vec2 fbuv = uv; // framebuffer transformed uv
+
+	const float sway = 0.1;
+	fbuv -= 0.5; // center at (0,0)
+	const float angle = 0.04 * sin(sway * time);
+	fbuv *= mat2(cos(angle), -sin(angle), sin(angle), cos(angle)); // rotate
+	fbuv *= 1.0 + 0.02 * sin(2 * sway * time); // zoom out
+	fbuv += 0.5; // restore center
+
+	// add transformed version of previous frame on top
+	color += texture(buf, fbuv) * 0.98;
 }